rkoeber
Member
- Location
- Salt Lake City, UT, USA
Here's my situation: I have a 277/480Y (solidly grounded) distribution panel, which I need to run a feeder from - to a 3? sub panel. The sub panel will only have 3? loads and 3 pole breakers and will never have any 277V loads. To save money I want to use 277/480Y slash rated breakers in the sub panel and also for cost I don't want to run grounded conductor to the sub panel (since it will not be used).
My questions are:
1. Do I have to pull a grounded conductor to the sub panel or can I eliminate it?
2. If I don't have to pull the grounded conductor, can I still use the slash rated breakers?
Here's what I've found so far (all from the 2011 NEC):
240.85 tells me that if the max voltage to ground is not over 277V then a slash rated breaker is acceptable (regardless of the presence of a grounded conductor in the panel or not because the sub panel is still a 277/480Y solidly grounded system).
215.2(A)(2) tells me that a feeder grounded circuit conductor must not be smaller than required by 250.122 (equipment grounding conductor size), but I beleive this applies only where the grounded circuit conductor is present - not a mandate that every feeder have a GCC.
Thanks in advance for the help.
My questions are:
1. Do I have to pull a grounded conductor to the sub panel or can I eliminate it?
2. If I don't have to pull the grounded conductor, can I still use the slash rated breakers?
Here's what I've found so far (all from the 2011 NEC):
240.85 tells me that if the max voltage to ground is not over 277V then a slash rated breaker is acceptable (regardless of the presence of a grounded conductor in the panel or not because the sub panel is still a 277/480Y solidly grounded system).
215.2(A)(2) tells me that a feeder grounded circuit conductor must not be smaller than required by 250.122 (equipment grounding conductor size), but I beleive this applies only where the grounded circuit conductor is present - not a mandate that every feeder have a GCC.
Thanks in advance for the help.