ECN Forum Forums Code Related Discussion NEC & other Code issues Table 310.15(B)(6) for separate panels

I have a client who's service upgrade to 400 amperes has been rejected by the POCO. They no longer allow the service lateral to come up inside the home and the want the service raceway visible all the way from the ground to the meter can. Power theft issues seem to be driving their position. I'm going to pitch a concrete encased service raceway to a semi flush meter can but I expect they'll reject that.

I now have to run feeder conductors from there new meter location to the lighting and appliance panel boards. Since the cost effective way to do this is by installing main breaker enclosures and converting the panels to main lug only it will call for one feeder to each panel. I believe this would call for the feeders to be sized in accordance with table 310.16 instead of Table 310.15(B)(6). That will mean 2" EMT and 250 MCM AL.

I know the local AHJ staff will accept 4/0 Type SE Style R cable and I'm tempted to use it since I must eat the additional labor but one of the panels supplies only pool and spa loads. The owners anticipate a hot tub and other heavy continuous duty loads on that panel which will eventually approach 160 amperes.

I suppose I could relocate the second panel to the new location and use 4 conductor 4/0 SER to the actual residential panel because right now the only load on that panel is the 100 ampere feeder to the existing pool equipment.

We've discussed this before and we have differing opinions on whether table 310.15(B)(6) can be applied to two or more feeders to a single dwelling.
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Tom Horne

If I understand you, there are 2 panels on the load side of the disconnect. One for the home load and one strictly for the pool/spa.
I think you could use 310.15(B)(6) to size the general lighting panel for the home (using the feeder O/C device to size the conductor) but you need 310.16 for the pool/spa panel.

That is why I may move the Pool / Spa panel to the new meter location. Meanwhile I'll have to supply the pool / spa panel by back feeding the homes lighting and appliance panel feeder and convert it to the other direction when the poco gets the meter can mounted.
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Tom Horne

If your inspector is on his toes he will say something about feeding a pool/spa panel with SER. Check NEC 680.25 '02 Edition. Don't know the exact reason why it's safe if it's existing but it's dangerous if installed new but that's what the words are saying.

I would be moving the pool and spa panel to the new service equipment location. It would be supplied through Flexible metallic Conduit from the meter cans terminal studs via 250 MCM Al service entry conductors. It's main breaker would be one of two service disconnecting means. The other would be the main breaker of the lighting and appliance (L&A) panel board that serves all of the homes other loads. I will convert the L&A panel to Main Lug Only (MLO) and install its main breaker in a breaker enclosure right beside the pool and spa panel at the location of the new meter can. Both the pool and spa panel and the L&A main breaker enclosure will be nippled from the back of the meter can. The existing feeder to the pool equipment panel runs right past that new service equipment location so all I will have to do is to shorten it. The new feeder that will supply the L&P panel from the main breaker enclosure at the new service equipment location will temporarily supply the pool and spa panel from the existing service location that the POCO now finds so unacceptable. If that is the use of SER cable that you think that AHJ staff will find objectionable then I just have to hope that they will accept it until cut over to the new meter when all will be well once again.
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Tom Horne

[This message has been edited by tdhorne (edited 05-06-2006).]