How do you figure the ampacity of wire feeding a single lamp holder for stage lighting? If the overcurrent is 20 amps, does each cord to each lamp holder (running through a dimmer pack) have to be #12? That is how I am reading 520.46.
How do you figure the ampacity of wire feeding a single lamp holder for stage lighting? If the overcurrent is 20 amps, does each cord to each lamp holder (running through a dimmer pack) have to be #12? That is how I am reading 520.46.
I heard this argument SO MANY TIMES:"Hey, the load is only 2 amps, why do I need #12 wire?"
Keep in mind the breaker is an Overcurrent Protection Device BEYOND the load. The breaker is an OCPD for a fault, not for the load. Under a fault you can have 19Amps and a 20A breaker won't trip, but 19Amps will melt a #16 wire.
Not to mention that part of code where "after all deratings the OCPD for a #14 Should NOT exceed 15A, the OCPD for a #12 SHOULD NOT exceed 20A, and the OCPD for a #10 SHOULD NOT exceed 30A. How would you be in compliance with that if your #14 has an OCPD of 20?
So yes, 20A breaker, #12 wire.
However, Manufactured whips may have an UL listing which tests the assembly under certain conditions and lists said assembly as acceptable.
