Commercial run service to sub

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Frank W

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Location
Lakeport, California
Occupation
Electrician
I'm looking to bone up on my commercial requirements for proper wire sizing from service panel to sub for a restaurant. For a 200 amp service I've been told it has to be 3/0 Nu. Id like to know exactly what code that it says specifically for future reference. I can't find it.
 
Basically it's all of article section 310.15 including the applicable Table, in your scenario it would be 310.15(B)(16)

Roger
 
It still doesn't reference specifically that a restaurant has to be at 3/0 verses 2/0 for a 200 amp service. I'm looking to find that code specifically.
 
The tables are the codes. 3/0 is rated for 200 amps while 2/0 is only good for 175 amps. The section before the tables gives us a relief on residences. Is that what you need to see.
 
Frank, the nec doesn't treat commercial work differently except for in a few cases. There are parts of the code like 210.52 which pertain only to dwellings but the code mostly applies to all.
 
Frank W said:
Does that imply that 3/0 is required for commercial installation then?
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What it implies is that if you want 200 amps you need 3/0. The exception is for a residence and that is 2/0.

But you can look at it that 3/0 is required for commercial work.
 
Frank W said:
It still doesn't reference specifically that a restaurant has to be at 3/0 verses 2/0 for a 200 amp service. I'm looking to find that code specifically.
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As Dennis says, generally speaking the NEC doesn't differentiate between commercial and residential installations. As a matter of fact, 3/0 would be required for a residential sub fed panel if it does not meet the requirement of 310.15(B)(7).

Roger
 
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