Section 13 — Electrical

Electrical Detail Design and Construction Practice

IPE Engineering Practice IPE-EP-13-2-1

Document number: IPE-EP-13-2-1 · Section: 13 — Electrical

• 600 Volts Power and Control Cable 29
• Receipt and Storage 29
• Installation 29
• Splicing and Stress Cones 31
• Conductor Color-Coding 31

RECEPTACLES 31

• Welding Receptacles 31
• Branch Circuits for Welding Receptacles 31
• Receptacles for 120 Volt 32

13.0 CATHODIC PROTECTION 32

14.0 FIRE ALARM 32

ELECTRIC HEAT TRACING 32

• Preferred Heater Selection 32
• Installation 32

DRAWINGS 33

• Construction Drawings 33
• Drawing Requirements 35
• As Builts 35

TABLES 36TABLES 36

Table 1 Minimum Sizes of Ground Conductors 36Table 1 Minimum Sizes of Ground Conductors 36

Table 2 Instruments Per Branch Circuit 36Table 2 Instruments Per Branch Circuit 36

Table 3 Device Mounting Height 36Table 3 Device Mounting Height 36

Table 4 Required Location For Expansion Fittings 37Table 4 Required Location For Expansion Fittings 37

Table 5 Minimum Cable Installation Temperature 37Table 5 Minimum Cable Installation Temperature 37

Table 6 Power Cables Without Metallic-Shielding or Armor 38Table 6 Power Cables Without Metallic-Shielding or Armor 38

Table 7 Welding Receptacle Cable Ampacity 39Table 7 Welding Receptacle Cable Ampacity 39

Table 8 Tray Spacing (Inches) 39Table 8 Tray Spacing (Inches) 39

Table 9 Tray-Conduit Spacing (Inches) 40Table 9 Tray-Conduit Spacing (Inches) 40

Table 10 Conduit Spacing (Inches) 41Table 10 Conduit Spacing (Inches) 41

Table 11 Ladder Type Cable Tray Load/Span Class Designations 42Table 11 Ladder Type Cable Tray Load/Span Class Designations 42

1.0

1.1

1.2

1.3

1.4

1.5

2.0

2.1

SCOPE

This Practice, along with IPE Engineering Practices, provides the detail design and installation requirements of Electrical Power Systems for facilities at process plants, laboratories, pump stations, buildings, etc. It is basically written for use by the engineering contractors design group, but can also supplement field design and installation engineers in understanding the Owner preferences and practices.

This Practice will be applicable to both new facilities and the modernization of existing facilities.

EP 13-1-1 for Power System Design, is to be used in conjunction with this Practice to provide the complete design from conception to detail design and construction requirements.

Any deviation from this Practice must be approved by the procedure described in EP 1-1-3. A revision bar indicates all changes made to this Revision.

REFERENCES

The latest published edition of the following standards and codes are referenced herein.:

STANDARDS AND PUBLICATIONS

STANDARDS AND PUBLICATIONS (Cont.)

DEFINITIONS

• Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
• Inspector - A Inflection Point Engineering, LLC appointed engineer or inspector.
• Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a Contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
• Owner - Inflection Point Engineering, LLC.
• Owner's Engineer - A Inflection Point Engineering, LLC appointed engineer.
• Purchaser - The party placing a direct purchase order. The Purchaser is the Owner's designated representative.

POWER SYSTEM

• General
• Power system basis design philosophy is described in EP 13-1-1.
• Power system arrangement is described in EP 13-1-1.
• Voltage Drop
• Bulk power feeder circuits 480 volt and higher from a circuit breaker to a transformer or to a motor control center shall not have more than a 2% voltage drop from the nominal voltage.
• The 480 volts and higher motor branch circuits from the starter to the motor shall not have more than a 3% voltage drop from nominal voltage during normal running conditions. Voltage drop during motor starting shall not exceed 8% of the nominal voltage.
• All other 480 volt circuits not previously mentioned shall have a voltage drop not exceeding 3% of the nominal voltage.
• The voltage drop for 208/120 volt branch circuits shall not exceed 3% of the nominal voltage.

GROUNDING SYSTEM

• General
• The grounding system shall be a loop system with radial taps to equipment. The ground system consisting of driven rods and bare copper cables will be installed throughout the job. All electrical and process equipment shall be grounded.
• Reference EP 13-15-1 for typical areas and sequential figures in the Practice for details.
• Grounds shall be made only to driven rods. Driven ground system shall be made up of sufficient rods to obtain a ground resistance not exceeding 5 ohms for general areas and 1 ohm for substations. Ground rods that are to be installed in test wells shall follow EP 13-15-1. Ground rods shall be of sufficient length to reach permanent moisture. Where the conditions are such that it is not practical to reach permanent moisture, the soil within a radius of 1 foot of the rod shall be treated with salt, calcium chloride, or copper sulfate to reduce the ground resistance.
• Oil, gas, or steam lines shall not be used for grounding purposes.
• Ground terminal connections to equipment shall be with pressure type connectors.
• All metal sections of cable tray and components shall be bonded together and effectively grounded to provide a continuous circuit to ground fault current. Ground all tray to supporting steel at intervals not to exceed 75 feet.
• Insulated pipe flanges and/or dry flow piping for flammable or combustible material shall have metallic bonding across the flange to insure electrical continuity.
• The electrical continuity of metal enclosures for electrical equipment including conduit and raceways shall be assured between enclosures and ground.

• A separate ground wire is required to be pulled with the ungrounded conductors in a conduit and it shall be insulated. The insulation shall be green or marked green as allowed under the provisions of the current issue of the NEC.
• Bonding and grounding conductors shall be bare stranded medium-hard-drawn copper.
• All motors shall receive an external ground connected directly to the ground system.
• Ground system testing shall be performed as outlined in EP 13-2-2 and shall meet the required ohmic levels as indicated in EP 13-2-1, EP 13-2-2 and EP 13-15-1.
• Grounded Equipment
• The following material and equipment as a minimum shall be connected to the electrical power grounding system:
• Conduit system.
• Cable sheaths.
• Steel poles.
• Switchboard and instrument board frames.
• Secondary neutrals of lighting transformers.
• Secondary neutrals of power transformers through a ground resistor including power transformers with a 480 volt secondary.
• Non-current-carrying parts of all electric apparatus.
• Metal enclosures of all switching equipment, including push-button stations.
• All structural steel work, including that of buildings and furnaces.
• Wire fences and metallic enclosures in the vicinity of electrical lines and apparatus.
• Towers and vessels containing flammable liquid.
• Cable tray.
• Electrical apparatus.
• Electric motors.
• Lighting equipment.
• The above material and equipment shall be joined directly to the grounding system by means of copper grounding conductors. The location (i.e. in power cable conduit), sizing and bonding of the grounding conductor (equipment) shall be in compliance with NFPA 70.
• All of the material and equipment within the battery limits which require grounding shall be connected into a common grounding system serving a plant unit, except stacks (See 5.7.5 of this Practice for stack grounding).
• Substation Yard Grounding
• A grid type ground system shall be provided under the entire substation for substations rated more than 600 volts.
• The grounding grid shall consist of, as a minimum, stranded #4/0 AWG, bare copper wire in a grid configuration with sufficient driven ground rods to obtain a system ground resistance of 1 OHM or less to reference ground. The size of the grid pattern and the size of the grid conductor and grid conductor depth shall be based on IEEE 80 to hold the calculated step and touch potentials to a safe value.
• Each intersection of the grid wires shall be connected by an exothermic weld process (Cadweld or IPE approved equal).

• Ground wire taps to equipment from the ground grid shall be a minimum of #2/0 AWG bare stranded medium hard drawn copper wire.
• Personnel ground mats shall be installed at all outdoor power circuit breakers and disconnect switches where personnel would be standing to operate or do maintenance work on the equipment.
• Structure Grounding
• All structures shall be grounded. Grounding is based on systems rather than on individual items. Typical grounding systems will require connections at the four corners of a large structure or at every 2nd or 3rd support of a line of steel pipe supports. Pipe racks in low density areas are to be grounded approximately every 150 feet.
• Grounding connections shall be made as shown in EP 13-15-1.
• Control House/Room Grounding
• The grounding for control house/room equipment shall be either:
• Single point (cluster) grounding with the safety grounds of the various cabinets isolated from the signal electronic reference ground. Except for a single point connection of the signal and safety ground.
• Multiple point grounding formed by grounding both the cabinet and the electronics to the local safety ground.
• NOTE: The method to be used is a function of the control room electronics, and must comply with the electronics vendors' requirements. In all cases the grounding requirements of the NEC (NFPA 70) shall be followed. See EP 13-15-1 for further details.
• Single point grounding shall be derived by providing a separate "clean ground" grounding system outside of the control house, that as a separate system measures 1 ohm or less. This system is then connected to the power system (safety) ground outside (underground) the control house. A tap from the clean ground system is then brought into the control house, being careful not to allow contact with the power system (building safety) ground except for the single point connection. The "clean ground", is to be used for electronics component grounding such as:
• Instrument signal cable shields.
• Electronics portions of panels, racks and computers.
• The power system safety ground shall be used for other grounding such as equipment frames, lighting, panelboards, structural steel, HVAC system grounding and etc.
• Receptacles used with single point grounding systems must be of the isolated ground type, Hubbell IG-5251 or equal, to insure the "clean ground" doesn't become tied to the building safety ground at multiple locations.
• With multiple point grounding, the power system ground is also the "clean ground". No special techniques or grounding methods are required, chassis and electronics grounds are bonded together throughout the system.
• Regardless of the type of grounding method chosen it is required that each piece of equipment connected to a power source be NEC grounded with a single ground wire back to the source. Do not daisy chain grounds from enclosure to enclosure.

• For all computer room circuits, including separately derived systems, it is recommended that neutrals be dedicated to only one circuit (load) and that the neutral only be connected (touch) to ground at one point, at the source. This will reduce common mode noise.
• Where the equipment data processing rates exceed 10 MHz a Signal Reference Ground (SRG) may be required to provide a low impedance ground path for electronics/signal circuits. The SRG grid as a minimum shall be 16 gage (0.051 inch) by 2 inch strips latticed on 2 foot centers, exothermic welded at crossings. A raised floor shall not be used as the SRG (See EP 13-15- 1). The requirement for a SRG shall be established by the process equipment Manufacturer.
• The SRG is not a safety ground and shall not be used as such. The SRG shall be grounded for safety with a "green" wire back to the clean (power safety) ground single point ground.
• All metallic objects that penetrate the SRG, in any plane, shall be bonded to the SRG at the point of penetration.
• All equipment/circuits grounded to the SRG shall use a strap the same size as the SRG strips and holding the length as short as possible.
• Grounding Conductors and Cables
• The conductors from the grounded equipment to the grounding loop shall be no smaller than No. 6 AWG bare, stranded, medium-hard-drawn copper. A heavier conductor shall be used if the setting of the protective device in the circuit serving the particular piece of grounded equipment is greater than 200 amperes, as specified in the National Electrical Code.
• The main grounding loop shall be no smaller than No. 2/0 AWG bare stranded annealed copper.
• Any conductors or cable installed above grade shall be supported by a malleable iron cable clamp, bronze cable clamp, or a cable clamp fitted with galvanized steel cap screws or cinch anchors. Clamps are to be spaced not more than 4 feet apart.
• Conductors or cable laid in the ground shall be at least 18 inches below grade, except under paved areas.
• All connections made below grade shall use the exothermic weld process (Cadweld or IPE approved equal) except those connections made in a ground test well (See EP 13-15-1 Figure 2).
• When non-metallic conduit is used in underground duct banks, an insulated stranded copper ground wire shall be installed in the conduit. Ground wire insulation shall be 600 volt.
• Power cable insulation shields, metallic sheaths and inter-cable ground connectors shall be grounded at cable terminations (both ends), and shall be continuous at splices and taps. All grounding connections should be to the shield and metallic sheath in such a way as to provide a permanent low resistance bond. Precautions shall be taken to prevent corrosion of the connection and grounding wire. Also see section 11 of this Practice for further information.
• Conduit used for physical protection of a groundwire when the groundwire is not run with its power conductors or for single ground wires used for equipment grounding shall be Schedule 80 PVC conduit or RGS conduit, if the groundwire is bonded to the RGS at both ends of the conduit by listed devices.

• Connection at Equipment
• A grounding conductor shall be attached to each motor, lighting panel, circuit breaker, pushbutton station, motor starter, etc. by means of a compression lug, cap screw and lockwasher, or equal. For cases when a hole is drilled and tapped for the cap screw into a foot or web of the apparatus, it shall be done in such a manner as not to weaken the structure. Under no circumstances shall the hole be drilled directly into the housing of the apparatus. Bolts or bolt holes intended for the mounting of the apparatus shall not be used for attaching the grounding conductor. This shall be in accordance with EP 13-15-1 ( Figure 5 ).
• The grounding connection to an uninsulated vessel shall be in accordance with EP 13-15-1. The connection to an insulated vessel shall be similar to that above, except that the plate shall be long enough to extend 3 inch beyond the outer surface of the insulation. The location of the steel plate shall be such that it will not be subject to possible damage by normal operation or maintenance, and will not create a trip hazard to personnel.
• All conduit connected to lighting panels, motor starters, or distribution switchgear shall be connected to grounding conductors by means of ground clamps (Burndy GAR, or equal) or grounding hubs to the grounded enclosure.
• Grounding conductors from two or more adjacent pieces of apparatus may be joined together by means of a Cadweld T connection before entering the ground.
• Stacks shall not be connected to the grounding system serving the electrical equipment. Grounding conductors shall be connected to each stack in a manner similar to that specified for vessels. The conductors shall be no smaller than No. 2/0 AWG bare stranded annealed copper and shall be connected to the ground rods, the type of rods, and the method of installing them shall be as specified previously in paragraph 5.7 of this Practice.
• Ground Rod Test Wells
• Ground rod test wells shall be constructed as shown in EP 13-15-1. Ground rod test wells are provided to permit sectionalizing and connection of ground system-testing equipment. Thus only 10 to 15% of the ground rods in an area require test wells. Not all ground rods require test wells.
• Ground rod test wells shall be located away from areas frequently used as accessways, walkways or operating areas.
• Ground well connections shall be made by mechanical connectors so that they can be removed for test purposes.
• Below Grade Grounding - General
• Minimum size for ground conductors is shown in Table 1.
• For systems which run equipment grounds with power conductors, ground conductor shall be sized per NEC Section 250.
• Grounding rods shall be copper clad steel, similar to copper weld and be a minimum of 10 foot long and 1 inch in diameter. The top of ground rods shall be at least 6 inches below grade.
• Where more than one ground rod is connected to a ground system, they shall be placed a minimum distance apart equal to twice the length of the ground rod.

• Tiles around ground rod test wells shall be used only for the grounding system.
• Ground wire shall be installed with sufficient slack to prevent breakage.
• New substation grounding and new ground loops shall be tied to existing substation/system grounding at multiple points (For exceptions, see Section 5.5.2).
• All below grade connections, taps, cable to cable, between cable and ground rods (not test well ground rods), or cable and steel shall be by an exothermically welded process ("Cadweld" or IPE approved equal).
• Ground conductors leaving grade or paving shall be protected by rigid steel conduit (RGS) or schedule 80 PVC as detailed in EP 13-15-1. RGS shall be bonded to the groundwire where it enters and leaves the RGS conduit by devices listed for this purpose.
• Metallic conduit systems stubbing up at above grade pull-points or at field located starter racks shall be grounded.
• Aluminum grounding wire (Authorized by Inflection Point Engineering, LLC for specific applications only):
• Where the grounding conductor is routed through concrete, it shall be protected and insulated from the concrete with schedule 80 PVC conduit.
• Underground aluminum ground wire shall be insulated stranded wire, 600V insulation. All underground connections are to be sealed by means of a scotch cast resin pressure splice kit (or equal) to insure that no bare aluminum comes in contact with the earth.

INSTRUMENT SYSTEM

• Power System
• Instrument power systems shall be designed with a high degree of availability which will require as a minimum two separate power sources. The two separate power sources shall be derived from two different buses (i.e. two different utility company buses). This compliments the requirement of critical DCS equipment having dual-separate AC power source inputs for each individual power supply.
• The electrical power distribution system to the instrumentation equipment shall be arranged and separated in a manner parallel to that of the instrumentation equipment. For example, if redundant power supplies are provided in DCS racks then the power system separation shall be continued down to the instrumentation equipment via separate distribution panels.
• Automatic or manual transfer switches are not recommended but can be provided as cross-ties between the separate critical power systems to provide:
• Isolation for maintenance.
• Backup power to critical redundant systems for equipment failures that would result in extended outages for repairs.
• NOTE: Automatic/manual transfer switches are not recommended because they violate the integrity of the instrument power source separation and its N-1 failure design basis.
• Distributed type process control systems, instrumentation, and critical shutdown circuits will normally require electrical power availability greater than that provided by the utility company or the plant distribution system. For these cases, a UPS (uninterruptable power supply) system should be provided. The following are general criteria for the UPS system:

• The UPS shall be provided with a manual bypass with complete isolation of the UPS from the electrical system.
• The alternate source for the automatic and manual bypass shall be a source other than the normal UPS source.
• The load panel connected to the UPS system shall be of the fusible switch type to provide proper fault coordination with the UPS protection and the load protective devices.
• Power supplies and control equipment with two separate AC inputs shall have each input source derived from a separate independent UPS system (see API 540 for instrument power system design).
• Equipment with single power source inputs, such as control consoles, shall have the multiple consoles split between the two UPS systems to provide coverage for the loss of on UPS power system.
• Branch Circuit Panelboards
• The 120 volt AC circuits to the instrument boards shall be supplied from a separate panelboard which serves only instruments and alarm circuits. This panel shall be the general purpose type and 15 ampere protective devices shall be used when the instrument panel is wired with No. 14 AWG wire. Approximately 20% spare protective devices shall be provided.
• Only a single classification of instrument as listed below may be connected on one branch circuit. The maximum number of instruments that may be connected to a single branch circuit are listed in Table 2.
• No single branch circuit shall have instruments located more than 30 feet apart on the instrument panel. Where instrument panels for two or more process units are located in the same control room, they shall be supplied from separate branch circuits.
• Instrument Panel Wiring

Refer to EP 12-1-1 "Control Systems".

• Instrument Area Wiring
• In addition to the requirements of Section 6.4 of this Practice, instrument wiring should comply with EP 12-1-1.
• Instrument DC signal wires shall be stranded copper with twisted, numbered pairs, with each pair shielded, PVC insulation for each conductor and overall shielding of aluminum backed mylar tape under an outer PCV coating with a bare copper drain wire. Main runs from the control house shall be 20 AWG multiconductor cable with insulated copper communication wire. Separate shielded pairs to individual instruments shall be No. 16 AWG. The lay of twist shall be 2 to 2-1/2 inches.

• It is preferred that main cable runs from the field to the control center or unit battery limits, be installed underground for fire protection. Overhead installation requires specific approval of the Owner. All underground control and instrument cables shall be in rigid galvanized steel conduits encased in a red concrete envelope. The top of duct concrete envelope shall be a minimum of 18 inches below grade. The field junction boxes shall be located a minimum of 24 inches above grade. For those cases where overhead cable runs are used, the junction box (centerline) shall be located 4 feet 6 inches (top of box not to exceed 6 feet 6 inches) above grade or platform and all conduits shall enter and leave from the bottom of the junction box. Where bottom entry is not practical, side entry with a drip leg and drain is permitted. Above grade installations shall use rigid conduit or MC cable when cables are not located in cable tray. Cables/wires in cable tray shall be in conduit or have MC type jacket or have PVC jacket only as approved by the Owner. Instrument cable runs shall avoid routings that are rated high fire probability areas and interfere with maintenance. ALL TRAY AND ABOVE GRADE CONDUIT ROUTINGS SHALL BE REVIEWED BY AND REQUIRE APPROVAL OF THE OWNER.
• Separate conduit systems shall be provided for each of the following types of instrument wiring:
• AC power and control conduits.
• DC signal.
• DC alarm conduits.
• Thermocouple extension wire.
• Data highway/data communication.
• Thermocouple wiring shall be the same as described in paragraph 6.4.2 of this Practice except with solid alloy conductors color coded to ISA standards and having individual shields for each pair, whether in single pair or multi-pair cables.
• Splices shall be kept to a minimum. When splices are required, terminal blocks with a water proof plastic spray shall be used.
• For temperatures above 140F, thermocouple wire shall have suitable insulation for high temperatures (asbestos type insulation not permitted).
• Shielded thermocouple extension lead wires shall be grounded at the thermocouple heads only.
• Pull pits when specified by the Owner shall be located between the control house and first field junction box. Barriers shall be installed in the pull pit to isolate control, thermocouple, alarm cables, and etc.
• Computer or data logging input circuits shall not be a part of the process measurement loop. Dropping resistors shall be used in this service on current type signals except for distributed control systems (DCS) and other integrated systems.
• Tubular clamp sectional terminal blocks shall be used throughout. The terminals shall be mounted on a raised base. Junction boxes shall be sized to allow a minimum 6 inch centerline spacing of terminal strips and a minimum of 6 inch clearance between walls and terminal strips and a minimum 6 inch box depth. Junction boxes for signal wiring shall consist of field boxes spotted by agreement with the Owner and a box inside the control house. All junction points shall be permanently identified with loop number, both on the wire and the terminal strip.
• Splices in the terminal box are not allowed. The boxes shall be numbered and tagged with engraved phenolic nameplates with black letters on a white background.

• Separate cable, conduit, and junction boxes shall be used for the following applications: DC control wiring; DC alarm wiring; thermocouple wiring; RTD (and compatible strain gauge) wiring.
• All field instrument wiring between a field measuring element and its associated field transmitter element shall be installed in separate conduits from the signal conduit.
• Separate cable, conduit and junction boxes shall be used for digital data links for multiplexers, computers, etc., and for data highway cables. However all such "digital" cabling may share common junction boxes and conduits.
• Conductors terminating on screw type terminals shall have insulated barrel crimp-type spade lugs.
• Shields shall be grounded as follows: (Reference IEEE Std. 518):
• The twisted pair shield should be grounded at one end only. This ground shall be the instrument ground (e.g., Honeywell master reference ground). It is critical that this shield be held to the instrument input reference ground potential.
• The overall shield must be grounded at both ends, and at appropriate points along the cable. The rule of thumb is to ground at internal of 1/8 the wave length of the worst case expected radio frequency interfering noise. This may prove to be either impractical and/or undefined, thus the recommendation is to provide multiple grounds by grounding the outer shield at convenient locations where the shield(s) are exposed such as at pull boxes, junction boxes and termination cabinets. Failure to ground at both ends and, to a lesser extent at intermediate points, renders that outer shield useless and in some cases can cause interference/false operation. The outer shield is to be grounded to the safety ground not the instrument ground.
• Unused twisted pair wires and shields shall be terminated and grounded where multiple- conductor cables are involved, half of the unused conductors and shields should be terminated and grounded at one end of the cable and the remainder at the other end.
• The use of metallic conduit, continuously welded metallic jacket, or covered trays is recommended as a means of providing additional grounded shielding.
• NOTE: The above shielding recommendations assume the use of instrument control/signal wire that is twisted pair, double shielded (each pair shielded with an overall cable shield). The shields shall be aluminum mylar tape with complete coverage.
• No splices or terminations shall be permitted in signal conductors except at terminal points approved by the Owner.
• Routing of overhead instrument circuits must be arranged to minimize exposure to fire hazards. Maintain a lower limit of 15 feet above pumps and exchangers.
• Terminal boxes shall be located so that they may be reached without ladders. Terminal strips mounted in terminal boxes must be mounted on separate mounting plates or brackets. Direct mounting on the back of the terminal box is not permitted.
• Unless specified otherwise, all exterior general purpose junction/pull boxes shall be NEMA 4x stainless steel.

• Wiring Level, Classes and Cable Spacing: IEEE Std. 518 has developed a system for signal circuit/class identification and combined this with spacing criteria. The following identifies some of the items in each level, a more detailed list is available in IEEE 518.
• Level 1 -- High susceptibility. Analog signals of less than 50V and digital signals of less than 15V.
• Common returns to high-susceptibility equipment
• Op-amp signals
• Power amplifier signals
• Logic buses feeding digital hardware
• All signal wires associated with digital hardware
• All wiring connected to components associated with sensitive analog hardware
• DC power supply buses feeding sensitive analog hardware
• Level 2 -- Medium susceptibility. Analog signals greater than 50V and switching circuits.
• Common returns to medium-susceptibility equipment
• DC bus feeding digital relays, lights and input buffers
• All wiring connected to input signal conditioning buffers
• Lights and relays operated by less than 50V
• Level 3 -- Low susceptibility. Analog signals greater than 50V, analog signals greater than 50V, regulating signals of 50V with currents less than 20A, and AC feeder less than 20A.
• Fused control bus 50-250 VDC
• Indicating lights greater than 50V
• 50-250 VDC relay and contactor coils
• Circuit breaker coils of less than 20A
• Machine fields of less than 20A
• All AC feeders of less than 20A
• Convenience outlets, rear panel lighting
• Recording meter chart drives
• Level 4 - Power, AC and DC buses of 0 to 1000 V with currents of 20 to 800A.
• Primaries and secondaries of transformers above 5 KVA
• Motor armature circuits
• Thyristor AC power input and DC outputs
• Static exciter
• Class Codes - Within a level, conditions may exist that require specific cables, and regrouping is not allowed. This condition may be identified by a class coding system similar to the following (See Table 8 for a class code condition):

S - Special handling of special levels may require spacing of conduits and trays, such as signals from communicating fields, or signals from power greater than 1000V or greater than 800A or both. NOTE: Other class codes are described in IEEE Std. 518.

• Table 8, Table 9, and Table 10 give IEEE Std. 518 recommended minimum spacing for various types of circuits and raceways. The instrument wire is twisted pair shielded with an overall cable shield with the inner shield ground at one point and appropriate multiple outer shield grounding.

LIGHTING AND 120 VOLT POWER SYSTEMS

• General
• Lighting panelboards shall be located throughout the process areas in approximate centers of the lighting loads. Area lighting shall be controlled by light sensitive switches (photo electric) aimed in a north direction and supervised with a hand-off-auto switch.
• The illumination of the instrument boards located in control rooms shall be such as to provide the foot-candles intensity on the face of the instruments, without glare, either directly from the lighting fixtures or reflected from the instruments or panels.
• Lighting system shall be designed to provide the lighting levels listed in the latest issue of the IES and comply with local codes.
• No service other than lighting shall be served from a designated lighting panel.
• All 120 VAC receptacle circuits shall be protected with GFCI type breakers.
• Lighting and Power (Low Voltage) Transformers
• Dry type transformers shall be 480-208/120 volt, Delta primary, Wye secondary, 3 phase, 4 wire, 60 Hz with Class H insulation 115_C rise, 4-2-1/2% FCBN and 2-2-1/2% FCAN standard taps in the primary winding.
• The transformer winding shall be compound filled/encapsulated and have a metal enclosure suitable for wall or rack mounting. Ventilated transformers to be used only in clean indoor atmospheres; non-ventilated transformers to be used in all other locations. Transformers shall be UL listed.
• The initial design load of transformers shall not exceed 75% of the transformer's rated capacity.
• Power for transformers shall normally be fed from 480 volt switch racks, or motor control centers. The transformer and feeder shall be protected by a circuit breaker on the switch rack or in the motor control center.
• The taps of all transformers shall be set so that the no-load secondary voltage is as close as possible but does not exceed rated nameplate voltage of user connected equipment.
• Panelboards and Switches
• All panelboards and switches in hazardous areas shall conform to the area classification. Panelboards and switches shall be UL listed.
• Branch circuit panelboards shall be located at accessible points within the battery limits. They shall be installed in locations where they will not be subject to possible damage by normal operation or maintenance.
• Molded case 120 volt circuit breakers shall have a 10,000 AIC or higher interrupting rating as required for the available fault current.
• Circuit breaker type (bolt-in or stab-in) shall be specified to match the type preferred at the facility.

• Three phase 208/120 volts panelboards shall be provided with 3 separate main buses, grounding bar, isolated neutral bar and single pole molded case circuit breakers for 120 volt branch circuits.
• The number of branch circuit breakers in each panelboard shall be such as to provide 2 spare breakers for each 6 in active service. No less than 2 spares shall be included in any panelboard.
• The panelboards shall be supplied with 20 ampere magnetic molded case circuit breakers. The initial loading of any 20 ampere branch circuit shall not exceed 1500 watts for a 120 volt system.
• The branch circuits that supply continuous illumination equipment, such as required at level gauges, shall not be used for any other lighting, but may be used for 120 volt receptacles.
• Explosion proof local switches shall be of the lever handle type.
• All lighting switches shall, in general, be placed between 6 and 4 feet above the finished floor or grade.
• All panelboards shall have a permanent complete typed circuit directory.
• Types of Fixtures
• Lighting fixtures in Division 1 areas shall be explosion proof construction, and properly rated for the classification of the area in which installed.
• Lighting fixtures in Division 2 areas shall be vapor tight construction, and properly rated for the classification of the area in which installed.
• Lighting fixtures for gauges (such as liquid level) requiring special illumination shall be of a local mounted type designed for the purpose.
• Control house lighting shall be as follows:
• Instrument Panels will be illuminated by rapid start fluorescent fixtures, with Holophane control lens, or Owner approved fixtures.
• General Control Room area and offices will be illuminated with fluorescent fixtures with a Holophane control lens, or other Owner approved lenses.
• Control room lighting shall not be sourced via UPS used for process control/computer equipment power sources.
• Location of Fixtures
• Lighting fixtures shall be located to obtain as uniform illumination as practicable, and to avoid objectionable shadows. On walkways and other outdoor areas, lighting fixtures shall favor landings of stairs or ladders, gauges, flow meters, panelboards, and other equipment requiring good illumination.
• Lights on walkways shall not be more than 8 feet above the walkway.
• Emergency Lighting
• Process area lighting with HID fixtures may be supplemented by incandescent lighting when a standby generator and automatic transfer switch are being supplied. Incandescent lighting loads are to be transferred automatically upon loss of normal power to the HID fixtures.

• Self-contained incandescent and/or fluorescent lighting with battery and battery charger are to be installed in control rooms, MCC room, and substation buildings.
• For HID installations without standby generation, provide HID fixtures with integral incandescent lamps in critical locations or instant restrike HID lamps.
• Quartz auxiliary amps shall not be used.
• Emergency control room lighting shall not be sourced from UPS that are used with process control/computer equipment.
• Wiring and Installation
• Wiring for 208/120 volt, 3 phase, 4 wire lighting systems shall not be circuited using a common neutral. The minimum size of neutral conductor shall equal the phase conductors.
• A grounding conductor (wire) shall be pulled in all lighting fixture and receptacle conduits and all fixtures and receptacles grounded to a grounding conductor.
• Receptacles shall be provided with a two wire circuit. Common neutral is not permitted.
• The maximum size lighting conduit shall be 1-1/2 inch. The minimum size shall be 3/4 inch.
• Minimum wire size shall be No. 12 AWG copper stranded. The maximum wire size shall be No. 8 AWG copper stranded.
• Fixture wire, Type SF-1 or SF-2 shall be used in all fixture stems and connections to fixtures.
• Fixture hangers, approved for the specific area classification, shall be used for all pendent fixtures.
• Mounting height of devices are shown in Table 3.
• The electrical subcontractor shall furnish and install Owner approved lamps for all fixtures.
• Stem-mounted fluorescent fixtures shall be supported by feeder stems in accordance with the Manufacturers' recommended practice with sliding, clamp-type hangers for supports.
• Supports from building structure shall be adequate to hold at least twice the weight of the fixture.
• Straps and hangers shall be heavy duty malleable iron or steel.
• Surface outlet boxes (to which fixtures are attached) and pull boxes shall be fastened to structure independently of conduit system supports.
• Unless specified otherwise, all exterior general purpose junction/pull boxes shall be NEMA 4x stainless steel.

AREA CLASSIFICATION

• The installation in classified areas shall be in accordance with Article 500 of the National Electrical Code and the classification of areas shall follow the recommendations set forth in API 500 and/or NFPA 497 (as applicable for chemical facilities). All material and equipment shall be UL listed or classified (FM listed equipment is acceptable when approved by the Owner) for use in the classified area in which it is installed and for the AIC available.

• Area classification plan drawings shall show (define) each source, define the material, volume and pressure at the source define the "T" rating (per NFPA 70 and 497) and include any factors that have a direct bearing on the classification. Area classification plan drawings shall also show the radius of the hazard from each source based on the API recommendation. Each area type shall be indicated on the drawing. Elevation views are desirable on vessels, reactors, buildings and dikes when different classifications apply at different elevations and when electrical equipment is located above grade within classified areas.
• Thought shall be given in the design of such things as compressor and pump buildings to either minimize or in some cases change the buildings division category. For example, a compressor or pump building with open sides might be classified as Division 2 rather than Division I. Electrical/instrument manholes and handholes shall not be located in classified areas without approval of the Owner.
• The basis of the area classification shall include a specific list of types of sources (e.g., pump seals, etc.), identification of the material available (type/volume), and any supportive assumptions/directives.
• Purging or pressurizing equipment and/or facilities in accordance with NFPA 496 shall also be considered as a means to reduce the classification of equipment/facility on a case by case basis. Economics will be the primary determining factor in evaluating these systems. The Owner's approval is required on these systems before they are implemented.

POWER AND (NON-INSTRUMENTATION) CONTROL WIRING

• Different Circuits Run Together
• Telephone and signal circuits operating at less than 65 volts may be run in the same cable, conduit, duct, tubing, or cable tray with each other, but not with circuits of higher voltage.
• Intrinsically safe circuits shall not be run in the same cable, conduit, duct, or tubing with non- intrinsically safe circuits. Intrinsically safe circuits may be run in the same cable tray with non- intrinsically safe circuits if:
• Intrinsically safe circuits are separated from non-intrinsically safe circuits by non- conducting or grounded metal partitions, or
• The non-intrinsically safe circuits are run in armored cables.
• More than one intrinsically safe circuit may be run in the same multi-conductor cable provided that at least 0.010 inch thickness insulation is used on each conductor.
• Non-intrinsically safe wiring inside of panels and junction boxes shall be segregated from all intrinsically safe wiring by positive means, such as inclusion in a raceway.
• Current transformer wiring, external to panels and switchgear, shall be in a conduit dedicated for this wiring only and splices allowed.
• Potential transformer wiring (used for protective relaying), run external to panels and switchgear, shall be in a conduit dedicated for this wiring only.
• Motor space heater circuits may be run in the same conduit with motor push-button circuits, between the motor starter and motor provided:
• Both circuits are insulated for 600 volts.
• The space heater circuit is not extended into the motor push-button enclosure.

• Motor control and power circuits may be run in the same conduit provided:
• Both circuits are insulated for 600 VAC.
• Power circuit wire size is less than #1 AWG.
• Power circuit is not extended into the motor push-button enclosure.
• Motor voltage is 600 volts or less.
• Motor Controls
• Medium Voltage Motor Control
• For synchronous motors, the control cable conduit grouping shall be as follows:
• D.C. field supply, start-stop push-buttons, shutdown contacts, permissive start contacts, and motor space heater wiring may all be in the same conduit.
• Motor stator RTDs and motor bearing RTDs wiring may all be in the same conduit.
• Current transformer wiring such as those used in differential relay circuits are to be in their own separate conduit.
• For induction motors, the control cable conduit grouping shall generally follow that outlined in paragraph 9.2.1.1 of this Practice for synchronous motors except for that wiring which is unique to a synchronous motor, such as the D.C. field wiring.
• For motors sourced via switchgear, local area panelboards such as lighting panels are not to be used for motor space heater power. Power needed for these uses should be derived from relatively secure panelboards such as those located in substation buildings, motor control center rooms or separate circuit breaker enclosures on switchracks.
• Switches that shut down motors shall be separate from those operating alarms.
• Motor RTD circuits shall be run in separate conduits.
• 480 Volt Motor Control
• Separate conduits shall be used for motor and control leads when motor leads are No. 1 AWG copper or larger.
• Switches that shutdown motors shall be separate from those operating alarms. No actuating device shall shutdown more than one piece of equipment.
• 115 Volt Motor Control
• Manual motor starters with overload devices shall be used for 115 volt single phase motors. Starters shall be located adjacent to their respective motors. Short circuit protection shall be provided by circuit breakers in the lighting and power panels.
• Starter operating handles shall have provision for locking in the open position only.
• Enclosures
• Unless specified otherwise, all general purpose junction boxes shall be rated NEMA 4x stainless steel and have hinged doors.
• All junction boxes shall be equipped with drains.
• All terminations shall be made with insulated barrel crimp type lugs on suitable screw type terminal blocks for circuits 600 volts and below.
• All conduits shall enter and leave from the bottom of junction boxes. Where bottom entry is not practical, side entry with a drip leg and drain is permitted. Bottom entry conduits from above grade conduit systems shall be provided with a water block and drain (drain seal is suitable).

CONDUIT AND TRAY SYSTEMS

• Conduit Systems General
• Rigid galvanized steel (RGS) conduits and fittings shall be hot dipped, highly ductile, conforming to ANSI C80.1 and UL6 aluminum conduit shall conform to ANSI C80.5. Conduits shall be delivered to the site in 10 foot (10'-0") lengths, threaded with a coupling on one (1) end and a plastic thread-protector on other end.
• All rigid conduit shall be threaded using NPSM standard thread. Continuously threaded conduit nipples shall not be used. Use close and short nipples with tapered threads. All threaded joints shall be made up with at least five (5) full threads engaged. Conductive thread dope, approved by the Owner's Engineer for this use, shall be used. The use of teflon tape of similar materials shall not be used on conduit threads. Paint all exposed threads.
• All aluminum threads shall be treated with an anti-seize conducting compound approved by the Owner for this use.
• All ends of conduit shall be capped during construction.
• Underground stub-ups and manhole penetrations shall be identified with permanent conduit tags having identification numbers per cable and conduit schedules. Conduit tags shall be attached with stainless steel wire or straps, tie wraps are not acceptable.
• When cable/conduit systems are installed within the battery limits of a process unit, and may be subject to damage by explosion or fire, the following guides shall be used:
• In the case of a double ended process substation, the raceway arrangement shall provide separation for the main power cables.
• Design of raceway installation shall be such that an explosion or fire in one process area will not damage cables supplying power to other process units.
• All sealing fittings shall be left unsealed until all wires have been pulled in, circuits tested and the Owner directs that the seals be poured. Newly installed seal fittings shall have their bodies painted yellow to show an unpoured seal. Following the pour, new sealing fittings shall be painted red to indicate a completed, poured seal fitting.
• Explosion proof (classified area) seals shall be installed, as required, in accordance with the National Electrical Code and project/plant approved area classification drawings even though they may be omitted on portions of the design drawings.
• Conduit shall be arranged to enter all field located panels, cabinets, terminal boxes, etc. from the bottom; side entry is permitted but a drip leg and drain shall be provided.
• Conduits shall not be supported from piping.
• Factory manufactured bends shall be used wherever practical. Field bends in 1 inch and smaller conduit may be made with a hand bender. For conduits larger than 1 inch, bending shall be done by mechanical hydraulic conduit benders that will not change the internal area of the conduit after bending.
• All conduit shall be terminated with Myers conduit hubs in sheet metal enclosures. Myers hubs shall have captive "o" rings, insulated throat with grounding lug and provided with positive binding to the box both mechanically and electrically. All tapped conduit openings without hubs shall have insulating sleeves (T&B "insuliner" or equal) designed to prevent insulation damage.

• Conduits run in tray shall be supported a minimum of every 6 feet 0 inches.
• Seals shall be sized to match the 40% conductor fill rating of the conduit to which it is attached. This can be accomplished by using a seal specifically designed and approved for 40% fill or use a larger seal with approved explosion proof reducers at the sealing fitting per the NEC.
• Underground Conduit
• Unless specified otherwise by the Owner, power and control circuits in the process area shall be underground in rigid galvanized steel or, when specified by the Owner, Schedule 40 PVC. All below grade conduits shall be in concrete encased duct banks. Minimum size shall be 1 inch diameter galvanized steel or 1-1/2 diameter PVC.
• All conduit for instrument wiring shall be rigid galvanized steel, both inside and outside the process area.
• Underground conduit for power and control outside the process area shall be RGS. Groundwire sleeving/raceway, when used, shall be Schedule 80 PVC.
• All underground power, control and instrument conduits shall be encased in a red concrete envelope. Concrete requirements are as follows:
• Concrete shall have a minimum compressive strength of 2000 psi in 28 days.
• Fine aggregate shall be per ASTM C33.
• Coarse aggregate shall be per ASTM C33 with a maximum size of 1/2 inch.
• All electrical and instrument duct banks shall be encased in red concrete. Concrete shall be dyed red throughout, not troweled in or painted red. Concrete shall be colored by one of the following or other equivalent Owner approved method:
• Coloring material shall be Sonobrite red cement color as manufactured by L. Sonneborn Products Company, 4 pounds of color material per cubic yard of concrete.
• Coloring material shall be red oxide C. K. Williams R-21 99, or equal 15 pounds of coloring per cubic yard of concrete.
• Wherever an underground conduit is brought up from below grade, the concrete shall be extended 6 inches above grade and tapered to prevent water from standing around the conduit.
• Underground conduit and/or duct bank locations and elevations are critical when they run near piping and sewers. All duct bank routings, elevations and section configurations shall be approved by a qualified Owner Electrical Power Engineer. Interference resolution shall be by a qualified Owner Electrical Power Engineer at the installed facility.
• The preferred method of installation is to install underground conduits such that they run beneath piping and sewers by 8 inches. If this method would result in excessive depth/costs (i.e., greater than 42" below grade, bottom of duct) then exception to this installation will be given by the Owner.
• Pull points shall be dictated by cable pulling tension calculations.
• All underground conduit duct banks containing power cables over 600 volts shall drain toward utility vaults, with a minimum slope of 3 inches drop per 100 feet.
• Duct bank runs under roads, railroads and possible laydown areas shall be steel reinforced. High vehicular traffic areas inside or outside the process area shall also be steel reinforced.

• At road and railroad crossings the top of the encasement shall be a minimum of 30 inches below surface of the road or rail base. For other areas the top of the concrete envelope shall be a minimum of 18 inches below grade.
• All duct run concrete pours, made on separate days, shall be firmly joined by steel reinforcing rods, with an uneven slough-off, not a square break.
• Provide continuous yellow plastic marking tape centered over duct, 12 inches above envelope. Tape shall indicate "Caution - Electrical Cables Below".
• The minimum separation between the outside surfaces of conduit in an underground bank shall comply with the requirements of the NEC Section 310 taking into account ampacity variances and spacing variances to minimize duct bank sizes.
• The minimum thickness of encasement shall be 3 inches on the top, and 2 inches on the sides and bottom.
• Factory manufactured long radius bends shall be used whenever possible. Design/field bends shall not be made with a radius less than specified in the NEC.
• Below grade PVC conduits, when specified by the Owner:
• Conduits shall be UL listed Schedule 40 or 80 heavy wall high density polyethylene.
• Conduit elbows, couplings, and similar fittings shall be heavy wall for installation in concrete encasement.
• Assembly of conduit and fittings shall be done using manufacturer's recommended adhesive to form water-tight joints.
• Conduit manufacturer's recommended methods (e.g., heat box) and equipment shall be used for forming/bending. Do not use torches.
• The minimum size conduit to be used is 1-1/2 inch.
• PVC conduit shall not extend above grade (except for ground wires). Transition to galvanized steel rigid conduit shall be made below grade and start prior to the 90° turn up to grade.
• All 90° bends shall use RGS conduit.
• Utility vaults (U.V.), manholes and pullboxes (P.B.):
• U.V., manholes and P.B. shall be precast unless impracticable because of size, shape or economics. Formed and cast in place U.V., manholes or P.B. must be approved by the Owner's Engineer.
• All U.V. shall be equipped with pulling eyes and ladder. As a minimum at least one pulling eye shall be located in the middle of each internal wall surface (including floor and ceiling).
• Generally, U.V. shall be installed in or along roadways.
• U.V. & P.B. shall not be installed in classified areas.
• When sizing U.V. consideration shall be given to the following factors:
• Wall space required for making up splices.
• Linear distance of straight sections for supporting splices and cables.
• Spaces required for bending and training cables and differences in duct elevations and changes in horizontal direction.
• Vertical wall space required for racking cable and splices.
• Adequate working area for cable pulling and splicing.
• Number of ducts (including futures/spares) entering the manhole and their elevation.

• U.V. shall have minimum inside dimensions of 72 inches square by 78 inches high. Minimum size top hole opening shall be 28 inches. When sizing the location, and type of top hole opening careful consideration shall be given to insure provisions (space) for cable (routing) pulling, entrance of cable trays, and entrance of conduits.
• U.V. shall be provided with an open sump hole in the bottom of the vault. Enclosed sumps are not recommended.
• Design, construction and installation of utility vaults, manholes, pullboxes and covers shall meet or exceed the expected traffic loading for the area in which they will be located.
• Provision shall be made for cable support in the manhole.
• NOTE: All references to U.V. shall also apply to manholes.
• Above Grade Conduit
• Above grade tray and conduit routings shall avoid high fire probability and physical damage routings (e.g., above pump seals, over roadways, etc.) and interference with maintenance. All tray and above grade conduit routings shall be reviewed and require approval of the Owner.
• Above grade conduits shall be rigid galvanized steel per ANSI C80.1 and UL6 except:
• In severely corrosive atmospheres rigid copper free aluminum per ANSI C80.5 or PVC covered rigid steel conduit may be used when approved by the Owner.
• Metal enclosed, weatherproof, and fireproofed wiring gutters may be used in special cases for large quantities of multi-conductor controls cables.
• Rigid copper free aluminum conduit may be used for all above grade conduits on cooling towers.
• Conduit shall be 3/4 inch minimum size except 1/2 inch may be used for short taps to equipment where required in or on a control or instrument panels.
• Conduits installed above grade shall be run exposed on walls, ceilings, or structures. They shall be run parallel or at right angles to beams, walls or columns, and where several conduits are run in a group, they shall be equi-distant from each other, with a minimum spacing of 1 inch between conduits. Diagonal conduit routing shall not be permitted without specific approval.
• Exposed conduits shall, in general, be supported by steel angle iron or galvanized unistrut support brackets that are welded or anchor bolted to structural steel or anchor bolted to masonry/concrete structures (conduit support brackets must be welded or anchor bolted to support structures not clamped). The use of other than galvanized steel unistrut shall be as specified by the Owner. Conduits shall be attached to conduit support brackets by u-bolts, or unistrut type clamps. Conduits shall rest on supports whenever possible. Corn clamps or similar devices shall not be used to fasten conduit to conduit supports.
• Exposed conduits shall be supported every 10 feet maximum.
• Conduit routing between tower platforms shall follow access ladders. The conduits shall be installed parallel to the ladder side rails. Conduits shall not cross in back of the ladder within 7 inches of the ladder rungs. Conduit support brackets must be welded to support structure not clamped.
• Expansion fittings shall be installed in straight above grade conduit runs as shown in Table 4.

• Conduits shall be installed at least 12 inches away from parallel runs of high temperature radiating surfaces (100°F or greater), and at least 6 inches away from such surfaces at crossings. Where such surfaces are insulated, conduit(s) shall clear the outer insulation surface by a minimum of 3 inches.
• Drain fittings or drain seals shall be installed in all low points of the conduit system. Drain fittings shall be provided (installed) in the bottom of all pull boxes, terminal boxes, local panels, etc.
• Where overhead conduits span between adjacent structures, the installation shall allow for the normal movement of the structures due to wind.
• Rigid steel conduit concealed in concrete walls or floors shall be 1 inch minimum size.
• Conduit Fittings
• Conduit fittings in Class I Division 2 areas shall be of the vaporproof gasketed type, with a corrosion resistant finish. Fittings material shall be Gray Iron Alloy cast material with cast Form 7 covers, or equivalent. Equivalent shall mean complete compatibility and interchangeability (e.g. Crouse-Hinds Feraloy and Appleton Grayloy).
• Drain fittings shall be provided at low points of long runs of vertically mounted conduit on outdoor towers and structures.
• All seal fittings shall be breakout Gray Iron Alloy-type material (Crouse-Hinds Feraloy and Appleton Grayloy).
• The preferred seal fittings for vertical installation are Crouse-Hinds type EZD, Appleton equal, with drain as required. EXD only shall be provided when inspection type seals are required. Other acceptable seals for vertical applications are Crouse-Hinds EYS and EYD (fitting with drain), or equal. All seals shall be sized to match the 40% fill of the conduit system, see paragraph 10.1.14 of this Practice.
• Seal fittings for general (horizontal) installations or bulkhead shall be Crouse-Hinds type EYS or Appleton equal.
• Seals for use on selected applications such as 4000 volt motors, instrument junction boxes, pull boxes and within substations shall be Crouse-Hinds type ES (or equal).
• Sealing compound, packing and installation shall be as recommended by the seal fitting Manufacturer.
• Flexible Metal Conduit
• Flexible metal conduit shall be liquid tight and suitable for the area classification in which it is installed. All flexible metal conduit and fittings must be listed, per UL1.
• Flexible metal conduit shall be used for connection between conduit and motor junction boxes and any equipment subject to vibration (e.g.: dry type transformers). The maximum length of flexible conduit runs shall be 36 inches, except as allowed for thermocouples.
• Flexible conduit connections to thermocouples shall be long enough to permit removal of the thermocouple without disconnection of the conduit, but shall not be excessively long.

• When flexible metal conduit is used with a metal conduit system, a bonding jumper shall be provided across the flexible metal conduit when required by the NEC. The external grounding wire (bonding jumper) shall be sized per the NEC, and all fittings shall be listed as "approved for grounding." In all cases the installation shall provide grounding as required to meet the NEC.
• Cable Tray (NEMA Standard VE-1 Tray System)
• Cable tray shall be made of fiberglass Enduro or equal.
• Cable tray shall be of the ladder-type with a 9-inch or less rung spacing with all rungs welded to the side members on a minimum of three sides.
• Side rail inside loading depth shall be 5 inches or more with dimensional tolerances per

NEMA VE-1, paragraph 2.3.2.3. Larger depths may be used, if required, to accommodate the size and quantities of cables in the tray.

• Cable tray design working load rating shall be 75 lbs/linear foot (symbol B) or higher as required.
• Cable tray load/span class designation shall be for a 75 lbs/ft working load or higher and the most cost effective span vs. cable tray design/loading, see Table 11.
• The cable tray and support system shall be in complete compliance with the current issue of NEMA VE-1.
• Support for cable trays shall provide strength and working load capacity sufficient to meet the static load and the dynamic loads during cable installation. Horizontal and vertical tray supports should provide an adequate bearing surface for the tray and should have provisions for hold- down clamps and fasteners. Vertical tray supports shall be provided with secure means, other than friction, for fastening the tray to the supports.
• Tray fittings
• Horizontal Cable Tray Fittings:
• Supports for horizontal tray fittings should be placed within two feet of each fitting.
• Supports for a horizontal tee tray fitting should be within two feet of each of the three openings connected to other cable tray items for 12 inch radius or less tee tray. On all other radii greater than 12 inches, at least one support should be placed under each side rail of the horizontal tee.
• Supports for a horizontal cross tray fitting should be within two feet of each of the four openings connected to other cable tray items for 12 inch radius or less horizontal cross tray. On all other radii greater than 12 inches, at least one support should be placed under each side rail of the horizontal cross.
• Vertical Cable Tray Elbows: Vertical cable tray elbows at the top of runs should be supported at each end. Vertical tray elbows at the bottom of runs should be supported at top of the elbow and within two feet of the lower extremity of the elbow.
• Vertical Straight Lengths: Vertical straight lengths should be supported at intervals dictated by supporting and building structures and design drawings without exceeding 24 feet on centers.
• Fittings at End of Run: A fitting which is used as the end of the run dropout should have a support attached to it, firmly reinforcing the fitting.

• A minimum vertical clearance of 12 inches shall be maintained from the top of cable tray to ceiling, beams, other trays, or other obstructions for 30-inch wide and smaller tray and 18 inches for 36-inch wide and larger tray.
• Sloping Trays: Sloping trays shall be supported at intervals not to exceed those of horizontal trays, of the same design for the same installation.
• Cable tray covers will be ventilated type with stand-off supports. Cable tray cover installation is required for all type cables other than CLX type power and control cables.
• Cable splices and taps, in trays, shall be made only by methods designed for the purpose and approved by the Owner.
• Expansion joints shall be installed every 100 feet and in locations where tray spans between structures.
• Unistrut used in conjunction with cable tray installation shall be copper free aluminum galvanized steel or stainless steel as approved by the Owner's site Electrical Engineer. All fasteners (bolts, nuts, clamps, etc.) shall be either stainless steel, aluminum or malleable iron.
• Tray splice plates/joints shall be listed as approved for grounding and shall provide tray-to-tray continuity for grounding. External copper bonding jumpers shall be used to insure electrical (grounding) continuity across each expansion splice plate.
• Trays shall not be supported by or attached to piping.

WIRE AND CABLE

• 5000 Volts and Above Power Cable
• For other detailed requirements see EP 13-8-2 and EP 13-1-1.
• Single conductor power cable is preferred for motor circuits. The decision on type of cable shall be based on application, location and local plant preference.
• Unless specified otherwise by the Owner, PVC jacketed bulk power feeder cables shall be three conductor cables with each power conductor having a PVC jacket and with the bundled three conductors having an overall PVC jacket.
• Cable conductor shall be stranded copper.
• Minimum cable size shall be #6 AWG.
• Cable Characteristics:
• 5KV Cable
• The semi-conductive layer shall be extruded.
• Insulation shall be rated 133%.
• Shield can be either copper tape or copper wire. Copper tape is preferred.
• Insulation shall be EPR.
• 15KV Cable
• The semi-conductive layer shall be extruded.
• Insulation shall be rated 133%.
• Shield shall be copper tape.
• Insulation shall be EPR.

• 34.5KV and 46KV Cable
• Unless specified otherwise by the Owner, 34.5KV systems shall use insulation rated 133%.
• The semi-conductive layer shall be extruded.
• Shield shall be copper tape (copper shield wire may be used (required) because of fault current available, but must be approved for use by the Owner).
• 46KV cable insulation shall be rated 100%.
• Insulation shall be EPR.
• 600 Volts Power and Control Cable

For additional requirements see EP 13-1-1 and EP 13-8-1.

• Receipt and Storage
• On receipt of cable, the protective covering shall be inspected for evidence of damage during shipment. Cable ends must be visible with end seals in place. Inspect end seals to insure they are of sufficient quality to prevent entrance of moisture.
• Unloading shall be accomplished so that equipment does not contact cable surface.
• If unloading is accomplished by crane, either a cradle supporting the reel flanges or a shaft through the arbor hole shall be used.
• A fork lift is not to be utilized in the handling of loaded cable reels since the forks may damage the cable.
• Reels shall be stored on a hard surface so that flanges do not sink into the earth.
• Reels shall be stored in areas where chemicals or petroleum products will not be spilled or sprayed, and where construction equipment, or falling objects will not contact the cable.
• When a length of power cable is cut from the reel the cable end on the reel shall be sealed with a heat shrink cap designed to prevent the entrance of moisture.
• Installation
• Installation, termination and testing of insulated power cable shall comply with the latest issue of ANSI/IEEE Std. 576, and the instructions in paragraphs 11.4 and 11.5 in this Practice.
• When cable has been stored outdoors in cold weather, cable should not be installed at temperatures lower than shown in Table 5.
• The minimum installed bending radius for cables shall be observed with minimum bending radii given as multiples of the outside diameter (shown in Table 6).
• Wire and cable pulling lubricants shall be as follows (NOTE: Verify that cable pulling lubricant is approved by the Manufacturer of the power cable):
• A UL listed commercial wire pulling lubricant such as "Polywater," "Ideal Aqua-gel," or "Ideal Yellow 77."
• Petroleum or petroleum based products are not acceptable.
• The Owner's Engineer and/or qualified Contractor's Engineer shall prepare and submit all cable pulling calculations substantiating the proposed underground/overhead design. The cable Manufacturer's pulling factors shall be included with the calculations. Contract Engineer calculations shall be reviewed and approved by the Owner.

• Calculations shall be based on ANSI/IEEE Std 576; CABLE C Cable Installation Manual (Sixth Edition); Engineering Data, Copper and Aluminum Conductor Electrical Cables (The Okonite Company); Installation Practices for Cable Raceway Systems (The Okonite Company).
• When approved by the Owner, maximum pulling tensions for cables when not calculated by the Contractor shall be determined from the following:
• Maximum pulling tension when pulled with a pulling eye attached to the conductor. Tm = 0.008 x N x CM

Tm = Maximum pulling tension in lbs. N = Number of conductors in cable

CM = Circular mil area of each conductor

• The maximum pulling tension shall not exceed 1000 lbs. for nonleaded cables pulled with a basket grip (Note that max. stress as determined by 11.4.7.1 above cannot be exceeded).
• The maximum pulling tension for leaded cables shall not exceed 1500 lbs per square inch of lead sheath area when pulled with a basket grip.
• The Contractor shall monitor pulling tension on all cable pulls. No cable pulls are to be made without the approval of the Owner's Engineer.
• Power cable insulation metallic shielding must be solidly grounded. Where conductors are individually shielded each must have its shielding grounded and the shielding must be carried across every joint to keep continuity of shielding.
• The shielding shall be grounded at both ends of the power cable (the Contractor shall verify by calculation the effect on cable ampacity, with results and recommendations made available to the Owner). All shielded power conductors shall be terminated with stress cones.
• Power cables and conductors when exposed shall be identified at each end, in manholes, and in pull boxes by cable number with permanent markers.
• All proper precautions shall be taken to avoid damaging the cables and/or the tray during installation on a cable tray system by observing the following:
• Using the proper tools and tool arrangements recommended by the tray Manufacturer.
• The cable pulling tension shall not exceed the values calculated per paragraph 11.4.5 and/or given in paragraph 11.4.7 of this Practice.
• The bending radius of the cables during the installation shall not be less than specified in paragraph 11.4.3 of this Practice.
• For multiple circuits on one continuous reel, field verifications shall be made of the lengths of cable runs before cutting the cable.
• Cables in manholes shall be fireproofed where two or more power circuits are exposed to each other, using Minnesota Mining Company arc proofing tape No. 7700 or an Owner approved equal. When single conductor power cables are used, each conductor shall be separately fireproofed.
• Shielded power cables shall be installed in one continuous pull with the cable in its raceway. Cables shall not be pulled out of the raceway and then pulled back in the raceway to complete a pull. If splices are required they must be reviewed and approved by the Owner. Cables may only be pulled out and back in a raceway when approved by the cable manufacturer using the installation method approved/designed by the cable Manufacturer.

• Splicing and Stress Cones
• 600 volt and lower wire and cable splices and taps shall be made with pressure type connectors. No solder connections shall be used. Splice kits shall be either preformed cold shrink or heat shrink.
• Current and potential transformer wires shall not be spliced.
• Power and control wires, as a general practice, shall not be spliced. Splicing shall only be permitted when approved by the Owner.
• Above 600 Volts:
• Commercial heat shrink kits are preferred for splices and stress cones for power cables up to and including 35KV.
• When specified, stress cones for 34.5KV cables can be G&W Electric Company type. All poured G&W stress cones shall be x-rayed to insure that no voids are present in the internal (porcelain) space around the prepared cable, and verify that a shrinkage void exists at the top of the porcelain (see manufacturers instructions).
• Splices can be of the taped method, with maximum attention to following instructions supplied with the tape kit.
• Power cables as a general practice shall not be spliced. Splicing shall only be permitted when approved by the Owner.
• In line splicing is preferred, with splices located in accessible locations such as manholes and pullboxes.
• Conductor Color-Coding
• Single and multi-conductor power wires shall be color-coded by insulation color or by tape in accordance with the NEC.
• Multi conductor control wire shall be color coded in accordance with EP 13-8-1.

RECEPTACLES

• Welding Receptacles

480 volt welding receptacles with circuit breakers shall be suitable for the classification of the area where installed and compatible with the existing receptacles at the location to be installed.

• Branch Circuits for Welding Receptacles
• The branch circuit supplying welding plug receptacles shall serve no other equipment. The receptacles shall be arranged in groups of not more than four outlets per circuit. The number of outlets on a circuit will determine the minimum cable size to be used. The current carrying capacity of the cable shall not be less than that shown in Table 7.
• The branch circuit shall be protected by an explosion-proof circuit breaker located at one of the starter racks within the battery limits. The setting of this breaker shall be such that if will not permit the circuit supplying the receptacles to become overloaded.
• Welding outlets shall be located within 150 feet of any structure or area in which welding is to be done. At ground level at least four welding outlets shall be available to each such area, arranged in groups of two.

• Receptacles for 120 Volt
• In classified areas, receptacles shall be specified for the application, and compatibility with the existing receptacles in the installed location. All outdoor 110 volt receptacles shall be GFCI protected.
• Receptacles shall be installed in the vicinity of all equipment both inside and outside of buildings. Receptacles shall be located so that all equipment can be reached with extension cords not over 50 feet in length. On vessels one receptacle will be located near every manway of the vessel.
• 15 ampere receptacles are approved for use only in the control house. All others shall be 20 ampere or higher as required.

13.0 CATHODIC PROTECTION

Cathodic protection is not required, unless specified otherwise in the project scope document.

14.0 FIRE ALARM

A fire alarm system is generally not required, unless specified otherwise in the project scope document.

ELECTRIC HEAT TRACING

• Preferred Heater Selection
• Where pipe or vessel maintenance temperatures are below 250°F, heating cables shall be of the self-regulating, parallel circuit, semi-conductive resistance type, unless the heaters will be exposed to temperatures exceeding their temperature limits. Heating cables shall be suitable for use on piping that can be steamed out.
• Where pipe or vessel maintenance temperatures are below 400°F and self-regulating heaters cannot be used, cables shall be of the constant wattage, parallel resistance type.
• Where pipe or vessel maintenance temperatures are above 400°F, heating cables shall be of the series resistance MI (mineral insulated) type.
• Installation
• MI cable heaters shall not be bent within 6 inches of the hot-cold junction. This is a particularly vulnerable point of MI heater construction.
• If heat trace cable requires a more secure attachment, the use of fiberglass adhesive tape is recommended. Stainless steel banding should be avoided because of the high risk of cuffing the heat trace cable.
• Do not exceed the recommended bending radius of any cable type heater. The minimum bending radius for MI cable is 6 x diameter.
• Heat transfer cement, when required, must be in contact with the heater cable and the object being heated for the entire length of the heater.

• When installing heater cables protected by steel channels filled with heat transfer cement, care must be taken to avoid pinching the heater cable between the steel channel and the object being heated.
• When heat transfer cement is used it must be kept dry until the insulation is applied. The use of polyethylene film or aluminum foil is recommended.
• Before heaters are applied to pipelines, all pressure testing of pipe must be complete.
• A clean surface is required in the areas where the heater cables are to be installed. All mill scale, rust, dirt, etc., must be removed by wire brush or other suitable means.
• A suitable weather resistant continuous tape label shall be placed on insulation stating "Danger Electric Heat Tracing".
• All heater cables shall have their insulation resistance tested as follows:
• When received by the electrical contractor.
• When installed, prior to insulating.
• When installation is completed.
• Heater cables shall have its insulation resistance tested with an insulation resistance testing instrument with the test voltage being the maximum recommended by the heat trace Manufacturer. Acceptable values will be as specified by the heat tracing Manufacturer.

DRAWINGS

• Construction Drawings

The following construction drawings and documents are required:

• Single line diagrams that reflect the basic distribution system involved in the scope of the project: Information required on single line drawings shall include but not be limited to the following:
• Starter configuration, sizing, and components
• Motor horsepower and RPM
• Metering
• Protective relaying and device tripping
• Fuses, including size
• Wire size (gauge) and number of conductors
• Conduit type and size
• Current and potential transformer ratios
• Interlocks
• Ratings for major components (e.g., transformers, breakers; power lines). To include but not limited to ampere, volts, fault MVA/current rating.
• Annunciation / alarms
• Three line diagrams for all three phase starters, switchgear, medium voltage substations and controllers: Detailed information for connection of all three phase equipment such as protective relays, CT's, PT's, power transformers and metering shall be provided on three line diagrams.
• Plot plan showing the location of all major equipment, conduit runs and overhead lines.

• Erection details for all major equipment, junction and pull boxes, panelboards, etc. One typical diagram may be used for similar installations.
• Physical location and identification of each conduit.
• Conduit and wire schedule showing: destination (from and to), conduit number, size and length, wire size, insulation, jacket, shielding and number of conductors in the conduit for all underground power control, alarm, and instrument circuits.
• Detailed wiring diagrams for alarm and instrument control circuits.
• Detailed interconnection diagrams: Generally not manufacturer's drawings, but rather drawings just showing terminal blocks with identification, location and wiring.
• Elementary control wiring diagrams: One typical diagram may be used for similar control schemes.
• Connection diagrams for all junction boxes.
• Connection diagram for complicated or unusual power and control circuits.
• Area classification drawings for the electrical equipment effected by the scope of the project: The area classification drawings shall show/identify all classified material sources per API 500, NFPA 497and NEC, along with materials volume and pressure (see Section 8.0 of this Practice). The drawings shall include not only classification on plot plan drawings but also classification on elevation drawings (see Section 8.0 of this Practice).
• Conduit and cable tray routings/locations including elevations.
• Complete manhole and duct bank details.
• Erection details.
• Drawing Requirements
• When possible, additions to existing areas and equipment shall be shown on existing drawings.
• Vendor drawings from mechanical and electrical equipment vendors shall be utilized whenever possible. Redrawing of vendor's drawings is not permitted.
• The Owner's Electrical Practices are not to be redrawn.
• Drawings shall be drawn on mylar using the following sizes:
• 8-1/2 by 11
• 11 by 17
• 24 by 36
• 18 by 24
• All lettering shall be a minimum of 1/8 inch high letters.
• All drawings shall be as simple and non-confusing as practical and contain sufficient information for the construction forces to proceed with their work.
• The normally open and normally closed position of switch and relay contacts shall be clearly designated in respect to the actuating conditions; in general, all microswitch and/or relay contacts shall be shown in the "shelf" or de-energized position.
• All drawings shall be produced on a CAD system.

• As Builts
• A complete set of "as built" drawings, drawings as listed in paragraph 16.1 of this Practice and EP 13-1-1 shall be provided covering all voltage levels down to and including 120 volt lighting transformers and lighting panels. Certified "as built" drawings shall be provided in electronic format as follows: Cals G4 TIFF (compressed).
• A complete set of "as built" calculations and Data Sheets shall also be provided.

TABLES

TABLE 1

MINIMUM SIZES OF GROUND CONDUCTORS

NOTE:

• Substation ground grid wire size shall be determined as outlined in IEEE STD 80.

TABLE 2 INSTRUMENTS PER BRANCH CIRCUIT

TABLE 3

DEVICE MOUNTING HEIGHT

TABLE 4

REQUIRED LOCATION FOR EXPANSION FITTINGS

TABLE 5

MINIMUM CABLE INSTALLATION TEMPERATURE

TABLE 6

POWER CABLES WITHOUT METALLIC-SHIELDING OR ARMOR

POWER CABLES WITH METALLIC SHIELDING OR ARMOR

CONTROL CABLES AND FLEXIBLE PORTABLE CABLE

TABLE 7

WELDING RECEPTACLE CABLE AMPACITY

TABLE 8

TRAY SPACING (INCHES)

NOTES:

• This Table indicates the minimum distance in inches between the top of one tray and the bottom of the tray above, or between the sides of adjacent trays.
• This Table also applies to the distance between trays and to power equipment of less than 100 KVA.
• When separate trays are impractical, Levels 1 and 2 may be combined in a common tray, provided the levels are separated by a grounded steel barrier. When Levels 1 and 2 are run side by side in trays, a 1 inch minimum spacing is recommended.
• Levels 3 and 4 may be run in a common tray, but should be separated by a barrier. Spacing should be Level 4.
• Tray to conduit transition spacings are potential sources of noise. Care should be taken to cross unlike levels at right angles and maintain required separations. Transition areas should be protected in accordance with the level recommendations.
• Trays containing Level 1 and 2 wiring should have solid bottoms. Ventilation slots may be used on other trays. Tray covers on Level 1 and 2 trays must be used to provide complete shielding. If wiring in trays is in conduit or are continuously welded, metallic jacket covers may be omitted and spaced as indicated in Table 10 .
• Trays containing Levels 1, 2 and 3S should not be routed parallel to high power equipment enclosures of 100KVA and larger at a spacing of less than 5 feet for trays and 2 1/2 feet for conduit.

TABLE 9

TRAY-CONDUIT SPACING (INCHES)

NOTES:

• Table indicates the minimum distance in inches between trays and conduits. This also applies to the distance between trays or conduits and power equipment of less than 100 KVA.
• Level 1 and 2 trays are covered. If trays are not covered, Table 8 spacing should be used.

TABLE 10 CONDUIT SPACING (INCHES)

NOTE:

This Table indicates the minimum distance in inches between outside surfaces of conduits being run induct banks. This also applies to the distance between trays or conduits and power equipment of less than 100 KVA.

TABLE 11 LADDER TYPE CABLE TRAY LOAD/SPAN CLASS DESIGNATIONS

NOTES:

• The above working loads are for cable only.
• See NEMA VE-1 for design safety factors and tray destruction load capacities (reference NEMA VE-1-1991, Section 3).

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