NEC Table 310.12 for 400 Amp Meter with (2) 200 Amp Load Centers

[jbrown2730]

I have an inspector and plan reviewer that will not allow me to use the Table 310.12 for sizing my feeders on a 400 amp residential service with 2- 200 amp load centers. Their interpretation of the code is that since the load is being split into 2 separate 200 amp panels, we have to use Table 310.16, and bump our feeders from 4/0 AL to 250 AL. The verbiage he noted is in note A and note B of 310.12. He emphasized that the entire load was not being used, so we could not use Table 310.12: "For a feeder rated 100 amperes through 400 amperes, the feeder conductors supplying the entire load associated with a one-family dwelling, or the feeder conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the feeder rating. If no adjustment or correction factors are required, Table 310.12 shall be permitted to be applied." I feel that these feeders are supplying the entire load, as the entire home is powered from these 2 load centers. Any sub-panel down line of these 2 load centers will be calculated using 310.16, but I do not believe these should. I am just looking for any feedback from anyone else that has ran into this.

 

[Dennis Alwon]

I agree with the inspectors however you can still use 4/0 as long as the calculated load is not more than 180 amps on each panel. Section 240.4(B)

 

[Dennis Alwon]

The problem is that neither panel carries the entire load of the service therefore 310.12 cannot be used

 

[infinity]

As Dennis noted #4/0 Al will work depending the calculated load. What size conductors are feeding the meter?

 

[slounsberry]

I actually have the exact opposite situation. I am trying to add a garage and want it on a separate service. The building inspector is telling me mo it had to co.e off the house 320 amp service. How foci get the inspector on my team. He is pushing hard
.

 

[augie47]

Is the garage attached or detached from the residence ?