310.15(A)(2) - Selection of Ampacities

[rbalex]

1.) NEC Section/Paragraph: 310.15(A)(2)
2.) Proposal Recommends: Revised Text
3.) Proposal:

310.15 (A)(2) Selection of Ampacity. Where more than one calculated or tabulated ampacity {,including those determined by 110.14(C),} could apply for a given circuit [length], the lowest value shall be used.

Exception: Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 3.0 m (10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less. {Where an ampacity determined by 110.14(C) is the lowest value, this Exception shall not apply. }

[FPN: See 110.14(C) for conductor temperature limitations due to termination provisions.]

For the Forum :
[deleted text]
{Added Text} in "Curly Brackets"

4.) Substantiation:

This is a coordinating Proposal to 110.14(C)(1). It recognizes that if the lowest ampacity value is determined by connections it is the overall limiting value. The FPN is made redundant by the direct reference

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Forum Note it would ultimately read:

310.15 (A)(2) Selection of Ampacity. Where more than one calculated or tabulated ampacity, including those determined by 110.14(C), could apply for a given circuit, the lowest value shall be used.

Exception: Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 3.0 m (10 ft) or 10 percent of the circuit length figured at the higher ampacity, whichever is less. Where an ampacity determined by 110.14(C) is the lowest value, this Exception shall not apply.

[ April 07, 2005, 02:24 PM: Message edited by: rbalex ]