Setting up multiple service panels

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jjhoward

jjhoward

Senior Member
Location
Northern NJ
Occupation
Owner TJ Electric
I am bidding on a job to install:
2 200A 1? service panels
1 100A 1? service panel
All in one building. The 200 amp panels are for 2 storefronts, the 100 amp panel is for a 2 bdroom apt over the stores. I am considering running 2 sets (2 hots, 1 neutral per set) of 4/0 CU conductors in 3" PVC to support the 500 amp capacity. In the basement I am looking to install a multi postion meter pan with 3 200 amp meter postions.
Question:
1) Must the service entrance conductors be rated for the sum of the individual service panels?

2)Is there an issue with installing a 200 amp meter hub and then having a 100 amp main? An inspector for the local POC warned me at another site that he could reject an install since I had a 200 amp meter pan and a 100 amp main breaker.

3) At the service head, can I get a multiphase head to allow 6 conductors?

Is there any other way to skin this cat?
Thanks
 
Re: Setting up multiple service panels

Originally posted by jjhoward:
1) Must the service entrance conductors be rated for the sum of the individual service panels?
Click to expand...
No, they are only required to be rated equal or greater than the calculated load.

Originally posted by jjhoward:
2)Is there an issue with installing a 200 amp meter hub and then having a 100 amp main? An inspector for the local POC warned me at another site that he could reject an install since I had a 200 amp meter pan and a 100 amp main breaker.
Click to expand...
Not a NEC issue but it could be a power company requirement.

Originally posted by jjhoward:
3) At the service head, can I get a multiphase head to allow 6 conductors?
Click to expand...
Yes.

By the way, two sets of 4/0s only results in 460 amps if in separate raceways.

Two sets of 4/0s in one raceway only results in a capacity of 416 amps.

[ April 26, 2005, 04:52 PM: Message edited by: iwire ]
 
Re: Setting up multiple service panels

Thanks Bob,
I did not account for derating w/more than 3 conductors in conduit. But when I do can't I derate the 250A rating for 4/0 CU at 80%?
500 x 80% =400??
 
Re: Setting up multiple service panels

310.15b is for dwelling services / feeders

but you can use 310.16 (260a for derating purposes only)(90 deg column)
 
Re: Setting up multiple service panels

Table 310.16 is for "Not More Than Three..."
Should I use values from table 310.17 to derate since there will be 4 current carrying conductors in the conduit?
 
Re: Setting up multiple service panels

Coppertree, No relation that I know of.

Jjhoward, Table 310.17 is for conductors in free air. You should use table 310.16 90 deg column for derating.

Jim
 
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