4/0 XHHW

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nizak

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I was recently turned down on a service inspection at a commercial building.

I set a 200 amp feed through panel adjacent to the meter base and fed through the structure basement with 4/0 XHHW Al conductors in PVC conduit to a 200 amp panel.

4/0 feeders were landed on the feed through lugs protected by the 200 amp main.

Inspection tag states that the installed conductors do not meet the ampacity rating of the OPD.

Chart lists this wire at 180 A 75 deg.

Next size breaker up is 200A

The total load computed is just over 100 amp.

Am I wrong??
 
nizak said:
I was recently turned down on a service inspection at a commercial building.

I set a 200 amp feed through panel adjacent to the meter base and fed through the structure basement with 4/0 XHHW Al conductors in PVC conduit to a 200 amp panel.

4/0 feeders were landed on the feed through lugs protected by the 200 amp main.

Inspection tag states that the installed conductors do not meet the ampacity rating of the OPD.

Chart lists this wire at 180 A 75 deg.

Next size breaker up is 200A

The total load computed is just over 100 amp.

Am I wrong??
Click to expand...

You are not wrong. Doesn't everybody learn the next size up rule in kindergarten?
 
I did a small commercial job and I asked the engineer if I could use 4/0 instead of 3/0 copper because the owner was trying to save money. He said that 4/0 is only good for 180 so I couldn't. Load was 110 amps and not much chance of increased load-- I told him what section to read and he said that was a new one on him-- he had no issue with it.
 
Dennis Alwon said:
I did a small commercial job and I asked the engineer if I could use 4/0 instead of 3/0 copper because the owner was trying to save money. He said that 4/0 is only good for 180 so I couldn't. Load was 110 amps and not much chance of increased load-- I told him what section to read and he said that was a new one on him-- he had no issue with it.
Click to expand...
You didn't say when this happened, but even if early in your career, chances are this has been the rule for a very long time and possibly was there before he was born.
 
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