ECN Forum Forums Code Related Discussion NEC & other Code issues Larger breaker downstream

Since I just argued this before the board I'll bite. The article reads dwelling not residence although in my opinion an apartment would be included in either of these. The feeder or feeders if located between the main disconnect and lighting and appliance panel or panels can be sized by 310.15(B)(6).

Now let me clear up my original post. The sub panel in question is a lighting and appliance panel. It is the only one inside the dwelling. The calculated load was 47.5 amps on this panel. It contained 2 small appliance circuits, 1 bathroom circuit, 2000sq. ft. lighting load, and 4 electric space heaters. I used 220.30 Optional calculation method since I had 4 unit heaters. The chairman of the board, much to my delight, was an electrical engineer, and initially had a problem with the diversity of load in the lighting and appliance sub panel. The outdoor service equipment panel has the range, water heater, dryer, laundry circuit, and the feeder breaker for the lighting and appliance panel in it. When I said 310.15(B)(6) allowed lighting and appliance panel or panels. His opinion of this was that the lighting and appliance panels were limited by a percentage of 20 amp circuits, and therefore the service panel did not meet the requirements for a lighting and appliance panels. When I read 408.14(A) and mentioned that in my home jurisdiction that ranges, dryers, and water heaters are appliances, he saw no problem with the installation.
There was also an electrical contractor who took issue with my calculation of the load in the sub panel, because he said the calculations only covered services and not feeders. When I pointed out 220.30(A) he saw no problem with the installation. Now if the AHJ had been that reasonable, this appeal would have never happened.
The 310.15(B)(6) issue was not part of the original appeal and the chairman asked the building official where did this come from. He responded that he just had a problem with it on his, subsequent to my appeal, visit to the job to see if he could find anything else to cite me for, only this time he thought he had 310.16 to use against me. He only showed his ignorance of the code once again along with what a jerk he is.

SolarPowered: That is exactly what I am saying. Feeder to an apartment, use 310.15(B)(6). Feeder to a swimming pool subpanel in a home, use 310.16. 310.15(B)(6) applies to services and feeders that supply power for _dwellings_, not anything else. We had a long discussion of this point here: https://www.electrical-contractor.net/ubb/Forum2/HTML/001450.html

It is my opinion that 310.15(B)(6) simply confuses the issue of proper conductor sizing. It seems to say that the ampacity of the conductors is different in this particular application. But it seems to me that what 310.15(B)(6) is really saying is that for a particular type of load (feeders to dwellings) a circuit which requires OCPD X and conductor ampacity Y, where Y is less than X.

This is done all the time for things like motors or welders, where the conductor ampacity might be half the OCPD trip rating. IMHO the service and feeder demand calculations should be modified to return _two_ numbers, one for required conductor ampacity, and the second number for OCPD rating. Doing the calculation on a dwelling might give a number such as 'this service requires an OCPD of 100A and a conductor ampacity of 80A', and the result would be a 100A main breaker and #4 conductors, matching what happens when 310.15(B)(6) is applied.

watthead: Based upon this last description, I agree that the feeder in question is the 'main power feed' of a dwelling and that 310.15(B)(6) applies. Sure sounds like the inspectors were looking for anything to hang a violation on, and I'm glad that you stuck with the appeal.

-Jon

Watthead
Let me offer my congratulations on taking a principled stand and sticking to it.

Some states are now considering instituting a statewide secondary appeals process. The advantage to such a system is that it provides a secondary avenue for resolution but more importantly the state appeals board decisions are precedent that is binding state wide. A local AHJ that is repeatedly overturned on appeal could be in danger of being decertified as a code official where upon he/she would have to be replaced.
--
Tom H

First let me also congratulate watthead on a victory.

Jon


I agree 100%



Do you really think that will lessen the confusion?

I understand your idea and agree it would work.

I have my own idea, remove Table 310.15(B)(6) and have everyone use 310.16

No one is saving a boat load of money by using Table 310.15(B)(6). The run length of the applications that table is designed for are generally short.

JMO, Bob

Watthead,I would also like to say congratulations.

I respect good inspectors and will gladly correct all violations when they are substantiated by code(s), or other reasons for safety.

I do have a problem with mavericks, be it police, inspectors, or any one in an authoritative position that will abuse their power.

I won't go into the 310.15(B)(6) issue, I think my stance is pretty well known.

Roger