service entrance cables

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bradd78

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I am currently working on an apartment building in southern Indiana. The lead electrician ha figured 2/0 aluminum SER for a 200 amp panel located 30 feet from the meter bank. {i have not done my own calculations as of yet}. I have never seen anything smaller then 4/0 aluminum allowed for a 200 service even when the meter and panel are back to back. I'm just curios if anyone knows of any circumstances where 2/0 AL ser would be allowed for 200 amp service.


please excuse my lack of doing the math before posting
 
bradd78 said:
I am currently working on an apartment building in southern Indiana. The lead electrician ha figured 2/0 aluminum SER for a 200 amp panel located 30 feet from the meter bank. {i have not done my own calculations as of yet}. I have never seen anything smaller then 4/0 aluminum allowed for a 200 service even when the meter and panel are back to back. I'm just curios if anyone knows of any circumstances where 2/0 AL ser would be allowed for 200 amp service.


please excuse my lack of doing the math before posting
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The lead electrician is incorrect or the service size is smaller than 200 amps. Now you can run 2/0 ser to a 200 amp panel as long as it is fused to the appropriate amps.

My guess is he is feeding a sub panel rated 200 amps but will have an ocpd at 125 or 100 amps at the main distribution panel.
 
Table 310.15(B)(6) permits a 4/0 aluminum SER cable that servers and the main power feeder to feed a 200 amp panel.

I suspect that the electrician looked at the copper column of 310.15(B)(6) and saw the 2/0 an missed that that is for copper not aluminum.


Chris
 
Is that panel for one of the apartments? (and the ONLY panel for that apartment?) If so, than you need 4/0 AL per 310.15(B)(6)

If not, than it would depend on the calculated load.

Also, what NEC cycle are you under?

SE cable can be used @ 75? C under the '05 NEC and previous, but you are restricted to the 60? C column under the '08 NEC.
 
Understand rating of SE cable has changed in 2008 code. Table 310.16 60 degree has 4/0 Al rated at 150 amps, but do you still get to use Table 310.15 (B)(6) to rate the cable at 200 amps for 4/0 AL
 
jgarner said:
Understand rating of SE cable has changed in 2008 code. Table 310.16 60 degree has 4/0 Al rated at 150 amps, but do you still get to use Table 310.15 (B)(6) to rate the cable at 200 amps for 4/0 AL
Click to expand...

Yes but only for dwelling services or feeders that carry the entire load of the service.
 
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