Jerseydaze
Senior Member
Bring a service to a detached garage then feed a home from detached garage? If you can how do you handle water grounds?
NEC 315(B)(7) said:120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders.
For individual dwelling units of onefamily, two-family, and multifamily dwellings, conductors, as listed in Table 310.15(B)(7), 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 each 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 between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling unit. The feeder conductors to a dwelling unit shall not be required to have an allowable ampacity rating greater than their service-entrance conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided the requirements of 215.2, 220.61, and 230.42 are met.
And in my opinion, if your service ends in a main breaker sub-feed panel, from which the feeder to the house is connected to the load ends of the busbars, and any other other circuit is fed from that panel, you would no longer comply with 315(B)(7) for undersized conductors, as that portion would not be a 'main power feeder'.
I did one last month: 4/0 AL to the garage service, and 250 kcmil AL to the house. I am not saying it makes sense in every application, but I cannot find the text that allows the 4/0 to continue after some load diversity has been removed.
Ok next question my plan is to bring 200 amps into garage and have 2 disconnects 1-50 amps 1-150 amps the existing main panel iin home is 200 amps do I need to separate grounds and neutrals ? do i need to change 200 amp breaker in home to 150 amp ?
Ive never understood this why would I want to put say two biger breakers then the service mains can handle what if in the future they add a hot tub ? I understand i can do it I just dont see why Id want to .
If your mains are at the garage then you need a 4 wire to the house. Separate equipment grounding conductor and neutral plus you need grounding electrodes (usually rods) at the house as well as at the garage.