215.2(A)(1)(a) and 240.4(B) Interaction

[wwhitney]

with 100 amp continuous load minimum conductor ampacity must be 125%.

Yep, that's what 215.2(A)(1)(a) says. And I'm questioning whether it's necessary. What's the hazard with 100A continuous load / 115A conductor ampacity / 125A breaker?

Cheers, Wayne

 

[kwired]

Yep, that's what 215.2(A)(1)(a) says. And I'm questioning whether it's necessary. What's the hazard with 100A continuous load / 115A conductor ampacity / 125A breaker?

Cheers, Wayne

I honestly don't know, but the 125% requirement has been there for a long time. Best guess is has to do with the fact that standard devices use the conductors as somewhat of a heat sink.