310.15(B)(6) for dummies

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Ponchik

Ponchik

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ceb58 said:
Show him this It would apply if there were one panel feeding all loads.
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ceb58 said:
What Dennis is saying is correct. If you installed a meter combo with say an 8 circuit panel built in. If you feed something like an outside A/C or well pump or whatever then you could not use table 310.15 (B)(6) for the feeders I.e.: 2/0 Cu. But if you brought those same loads back out of the main panel then you could use 2/0. So by the way it is written in the case of a meter combo with branch circuits you must increase the wire size for lowering the amp load on the wire. :?:?:?
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So if I have a 24 circuit meter main outside with a subpanel inside of the dwelling, then I can not use 310.15(b)(6) for the service conductors???

However, I can use 310.15(b)(6) if ALL of my load and branch circuits are fed from the meter main combo and there is no subpanel anywhere.
 
Dennis Alwon

Dennis Alwon

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edward said:
So if I have a 24 circuit meter main outside with a subpanel inside of the dwelling, then I can not use 310.15(b)(6) for the service conductors???

However, I can use 310.15(b)(6) if ALL of my load and branch circuits are fed from the meter main combo and there is no subpanel anywhere.
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Again it depends-- if no other loads are in the exterior panel then you can use (B)(6). It all has to do with diversity of the load. This is why 2- 200 amp panels don't qualify. Someone will put all the heating loads in one panel and the rest in the other or whatever mix it has it will not help with diversity that (B)(6) is based on.

Now I agree it makes no sense in some cases however it is what we got. Generally speaking there is very little load on a house about 90% of the time
 
jumper

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edward said:
So if I have a 24 circuit meter main outside with a subpanel inside of the dwelling, then I can not use 310.15(b)(6) for the service conductors???

However, I can use 310.15(b)(6) if ALL of my load and branch circuits are fed from the meter main combo and there is no subpanel anywhere.
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Ya get to use 310.15(b)(6) if no loads are in your sub panel.

Clear as mud??:)
 
ceb58

ceb58

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Raeford, NC
edward said:
So if I have a 24 circuit meter main outside with a subpanel inside of the dwelling, then I can not use 310.15(b)(6) for the service conductors???

However, I can use 310.15(b)(6) if ALL of my load and branch circuits are fed from the meter main combo and there is no subpanel anywhere.
Click to expand...
Correct. What you cannot do is use the table for the conductors between the meter base and sub panel. If you install a meter base combo and feed any associated load from that combo then the conductors would have to be 3/0 between the combo and panel not 2/0 per the table. (200 amp service). In Chris's case he has a 400 amp meter combo with 2-200 amp breakers feeding 2-200 amp panels. You cannot use the table in this situation ether because you do not have a single panel feeding all loads. Same thing as if you have a 400 amp meter base (320 A) You will have 2 panels feeding the loads.
 
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