Cable

Module from the Electrical Engineering Curriculum curriculum.

Module 5 - Cable, Conduit, and Raceway · Learning Objectives · 1. Apply NEC Table 310.16 ampacity and derating factors · 2. Compute conduit fill per NEC Ch. 9 Table 1 (2 conductors 31%, 3+ conductors 40%) · 3. Select cable insulation: THHN, XHHW-2, MV-105, TC for tray · 4. Apply cable tray fill per NEC Art. 392 (multi-conductor <4/0: 50% fill) · 5. Size for voltage drop <3% feeders, <5% total (branch + feeder) · NEC 310.16 Copper Ampacity (75C terminations, THHN/THWN-2)

Size AWG/kcmil	Ampacity 60C	Ampacity 75C	Ampacity 90C	Typical Use	Notes
14	15	20	25	Control circuits	Smallest branch
12	20	25	30	Branch circuits	Most 20A receptacles
10	30	35	40	Small HP motor	3 HP 230V
8	40	50	55	Motor feeder	5-7.5 HP 230V
6	55	65	75	Motor feeder	10 HP 230V
4	70	85	95	Feeder	20 HP 230V
2	95	115	130	Sub-feeder	Panelboard feeder
1/0	125	150	170	Sub-feeder	200A panel
4/0	195	230	260	Service	400A service
250 kcmil	215	255	290	Service	500A
500 kcmil	320	380	430	Service	700A

Source: Electrical_Engineering_Curriculum_v1.xlsx · Sheet: Cable

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