wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
408.36 requires a panelboard to protected by an individual OCPD, or under the exception, two OCPD that sum to not more than the panelboard rating.
For a feeder to a panelboard, suppose a load side connection is made in the middle of the feeder under 705.12(B)(1). If the panelboard has a main breaker, then that satisfies 705.12(B)(1)(b) and 408.36 and all is well.
So when does 705.12(B)(1)(a) come in, where the load-side segment of the feeder is increased in ampacity? Does its use necessarily require the use of 408.36 Exception? An example would be a 150A service disconnect, a 150A feeder segment to the point of interconnection of a PV source from a 50A breaker, and a 200A feeder segment from the interconnection point to a 200A MLO panel. I don't see any other way to utilize 705.12(B)(1)(a).
BTW, if the service in the example is residential, then 310.15(B)(7)(3) applies. That seems to say the "200A" feeder segment need not be larger than 83% * 150A (the service rating), which definitely seem wrong.
Cheers, Wayne
For a feeder to a panelboard, suppose a load side connection is made in the middle of the feeder under 705.12(B)(1). If the panelboard has a main breaker, then that satisfies 705.12(B)(1)(b) and 408.36 and all is well.
So when does 705.12(B)(1)(a) come in, where the load-side segment of the feeder is increased in ampacity? Does its use necessarily require the use of 408.36 Exception? An example would be a 150A service disconnect, a 150A feeder segment to the point of interconnection of a PV source from a 50A breaker, and a 200A feeder segment from the interconnection point to a 200A MLO panel. I don't see any other way to utilize 705.12(B)(1)(a).
BTW, if the service in the example is residential, then 310.15(B)(7)(3) applies. That seems to say the "200A" feeder segment need not be larger than 83% * 150A (the service rating), which definitely seem wrong.
Cheers, Wayne