Originally Posted By: roconnor
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The maximum ampacity of a #14
THHN would be 25A (NEC 310.15). While #14
TFFN (and other types of fixture wires) would have a lower maximum ampacity of 17A (NEC 402.5).
Yet it seems #14 TFFN at 17A capacity would be allowed to have an unlimited tap length on a 30A BCW/OCP that may not trip until it reaches a 38A draw. That's what I thought was unusual, but I understand where Bob is coming from ... just didn't notice those provisions before and have to chew on that one for a bit ... ![nachi_sarcasm.gif](upload://6HQh6KbNiD73gqTNQInjrR2zeJw.gif)
But the wire usually must match the breaker, except for some very limited exceptions ... especially in a home with the lower grade wiring ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)
Robert O'Connor, PE
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I am absolutely amazed sometimes by how much thought goes into doing things wrong