NEC Table 450.3(A) Note 2 states "Where secondary overcurrent protection is required, the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location." Can you have 15kV switchgear with a CPT and 6 fuses for 6 feeders? Or are you limited to a CPT and 5 fuses for 5 feeders? I guess I am trying to determine if the CPT is considered one of the six overcurrent devices.
NEC 450.3 "Six Handle Rule"
- Thread starter jrinehart
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SG-1
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Inside the switchgear the CPT should have primary fuses, but they are for short circuit protection not overcurrent protection. On the secondary side of the CPT there should be a single overcurrent protective device to protect the CPT from overload. After that you can have as many circuit breakers as you want. Inside the switchgear any number of breakers may be grouped together in a panelboard, central location, or scattered throughout the compartments.
The NEC does not have much say as to what is inside the gear.
The NEC does not have much say as to what is inside the gear.
I guess I am trying to determine if I need a secondary main breaker. There will be 7 cubicles of switchgear (one for the CPT and six with switch and fuse) for the 6 feeders. Or can I only have 6 cubicles (one for the CPT and five with switch and fuse) for 5 feeders without having to have a secondary main breaker?
SG-1
Senior Member
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- Ware Shoals, South Carolina
I would recommend a secondary main breaker. This is standard in our assemblies. When I worked for Westinghouse it was standard in their MV Switchgear also, DHP, Vac-Clad, & World Cell.
Factory assembled switchgear does not use the NEC except to size conductors & OCPDs for non-control circuits. This is done to comply with IEEE C37.
Factory assembled switchgear does not use the NEC except to size conductors & OCPDs for non-control circuits. This is done to comply with IEEE C37.
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