Source of PDU De-Rating

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In researching PDU's I have noticed most cite a derated current at the 80% level. For example, 30A is derated to 24A:

Tripp Lite:

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Raritan:

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Does anyone have anything that shows what agency this is (NEMA?) and these actual regulations? Also, does anyone have any advice, based on actual experience, on how dangerous it is to push above these limits?

Best Answer

Promoting my comment to an answer...

Does anyone have anything that shows what agency this is (NEMA?) and these actual regulations?

This requirement comes from the National Electric Code, which is published by the National Fire Protection Association

National Electric Code requires that the continuous currentNote 1 drawn from a branch circuit not exceed 80% of the circuit's maximum rating... 24A is 80% of 30A. This 80% derating scheme is sometimes referred to as the Maximum Current Rating; it refers to the measurable current load through the device in question.

See Sizing a circuit breaker, which does a much better job than I could at describing the NEC rules.

Also, does anyone have any advice, based on actual experience, on how dangerous it is to push above these limits?

I have no experience here, but I personally wouldn't recommend it. Since these guidelines come from the NEC, violating these design guidelines could get you in hot sauce with your insurance provider / lawyer / fire marshal if there was ever a reason for a claim.

Note 1: Continuous current is any load sustained continuously for at least 3 hours

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