2 sets in a 3 inch pvc-sched 80

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lpelectric

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In Chapter 9 at Table 1 in the "over 2 conductors" column, I'm using 40% conduit fill.
Over 40% for a 3" schedule 80 pvc is 2.577 square inches.
4/0 RHW-2 = 0.4754 each times 4 = 1.9016
2/0 RHW-2 = 0.3505 each times 2 = 0.701
These two figures total 2.6026 which is 0.049 over.

So 2 sets of paralleled conductors (200 amp urd) in 3" is over.
The conduit length from the padmount to the service pedestal is 20 feet. Does derating apply? If so, where is this in the code?
Thanks. :smile:
 
lpelectric said:
In Chapter 9 at Table 1 in the "over 2 conductors" column, I'm using 40% conduit fill.
Over 40% for a 3" schedule 80 pvc is 2.577 square inches.
4/0 RHW-2 = 0.4754 each times 4 = 1.9016
2/0 RHW-2 = 0.3505 each times 2 = 0.701
These two figures total 2.6026 which is 0.049 over.

So 2 sets of paralleled conductors (200 amp urd) in 3" is over.
The conduit length from the padmount to the service pedestal is 20 feet. Does derating apply? If so, where is this in the code?
Thanks. :smile:
Click to expand...

Derating applies when you have more than 3 current carrying conductors in a raceway. See table 310.15(B)(2)(a).

The conduit length is not relevant once it exceeds 24".

This sounds like a test question.
 
What is your question. If it is "Can I install these conductors in a 3" conduit since it is only .049 sq in over the limit"? The answer is no. Over is over no matter how small the number. When the code says you shall not exceed 40% they do not add it is OK to exceed by a little bit.
 
haskindm said:
What is your question. If it is "Can I install these conductors in a 3" conduit since it is only .049 sq in over the limit"? The answer is no. Over is over no matter how small the number. When the code says you shall not exceed 40% they do not add it is OK to exceed by a little bit.
Click to expand...

No. I agree. Over is over. I was just wondering if any additional rule applied that would have further limited this install.
 
petersonra said:
Derating applies when you have more than 3 current carrying conductors in a raceway. See table 310.15(B)(2)(a).

The conduit length is not relevant once it exceeds 24".

This sounds like a test question.
Click to expand...

Thanks. Not atest question, although it would probably make a good one. :smile:
 
lpelectric said:
Switching to THWN-2 makes the job compliant. Thanks. The guy has already run the service. Too late. :mad:
Click to expand...
If I were the inspector, I think I would might overlook such a minor violation. It is just that trivial.
 
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