DrSparks
The Everlasting Know-it-all!
- Location
- Madison, WI, USA
- Occupation
- Master Electrician and General Contractor
I would like to finally know the conclusive answer to this question that's been gnawing away at me for quite some time. It still seems to me to be a gray area in the NEC that even most inspectors don't know the answer to. The NEC states:
*For dwelling units, conductors, as listed below, shall be permitted as 120/240 volt, 3 wire, single phase service-entrance conductors, service lateral conductors and feeder conductors that serve as the main power feeder to a dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panel board(s) and the feeder conductors to a dwelling unit shall not be required to be larger than their service entrance conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors provided the requirements of Sections 215.2, 220.22 and 230.42 are met.
It states that the residential table applies to "main power feeder" to a "dwelling unit". Does that include the feeder from a 100-amp main breaker at an outside meter base to the subpanel in an apartment unit? Or do I need a 90-amp breaker for each unit? FYI: I've ALWAYS gotten away with 100-amp breakers. I just want to know the answer.
Thanks!
*For dwelling units, conductors, as listed below, shall be permitted as 120/240 volt, 3 wire, single phase service-entrance conductors, service lateral conductors and feeder conductors that serve as the main power feeder to a dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panel board(s) and the feeder conductors to a dwelling unit shall not be required to be larger than their service entrance conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors provided the requirements of Sections 215.2, 220.22 and 230.42 are met.
It states that the residential table applies to "main power feeder" to a "dwelling unit". Does that include the feeder from a 100-amp main breaker at an outside meter base to the subpanel in an apartment unit? Or do I need a 90-amp breaker for each unit? FYI: I've ALWAYS gotten away with 100-amp breakers. I just want to know the answer.
Thanks!
