10% of the total circuit clarification

DrDefecto

Member
Location
Portland, OR
Occupation
Electrician
Hey, I take the Journeyman test next month and am looking for some clarification.

The exception to 310.14(A)(2) allows you to use the higher ampacity as long as the derated portion is less than 10' or 10% of the total circuit.

I don't think it does, but the question is if this would overrule the adjustment factors for metal wireways when you exceed 30 CCCs in a cross section.
 
Hey, I take the Journeyman test next month and am looking for some clarification.

The exception to 310.14(A)(2) allows you to use the higher ampacity as long as the derated portion is less than 10' or 10% of the total circuit.

I don't think it does, but the question is if this would overrule the adjustment factors for metal wireways when you exceed 30 CCCs in a cross section.
It is the lesser of 10' or 10% of the circuit length, and it does, in many cases, eliminate the ampacity adjustments in wireways.
 
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