jhnnagle
Member
- Location
- Cleveland, Ohio, USA
As I understand things from the NEC:
240.21(C)(3) - For industrial installations, you do not need overcurrent protection at the transformer if your secondary conductors are not over 25 ft, the conductors can carry the full load current of the transformer, and the sum of over current devices does not exceed the ampacity of the secondary conductors.
240.21(C)(6) - For other installations, you can use conductors not over 25 ft that terminate in a single set of fuses. These conductors must be at least 1/3 of the primary overcurrent device referred to the secondary side.
As far as I can tell, the advantage of 240.21(C)(3) is that you can have multiple sets of fuses. 240.21(C)(6) only lets you use one set.
My question:
Do I have to use 240.21(C)(3) for any industrial installation or can I use 240.21(C)(6)?
240.21(C)(3) - For industrial installations, you do not need overcurrent protection at the transformer if your secondary conductors are not over 25 ft, the conductors can carry the full load current of the transformer, and the sum of over current devices does not exceed the ampacity of the secondary conductors.
240.21(C)(6) - For other installations, you can use conductors not over 25 ft that terminate in a single set of fuses. These conductors must be at least 1/3 of the primary overcurrent device referred to the secondary side.
As far as I can tell, the advantage of 240.21(C)(3) is that you can have multiple sets of fuses. 240.21(C)(6) only lets you use one set.
My question:
Do I have to use 240.21(C)(3) for any industrial installation or can I use 240.21(C)(6)?
