SJO cable voltage rating

[frankwatson]

SJO cable has a rating of 300V. Is this rating from conductor to ground or conductor to conductor? If I have 2 legs of a 480V 3 phase circuit and a ground the potential to ground is 277V but conductor to conductor is 480V.
Any ideas on the NEC position on this issue?

Thanks,
Frank

 

[raider1]

The voltage would be the maximum voltage between any two conductors of the circuit. So if you were installing a 277 volt single phase 2-wire branch circuit you would have 277 volts between the ungrounded conductor and the grounded conductor. But if you were installing a 277 volt multiwire 3 or 4 wire branch circuit you would have 480 volts between the 2 or 3 ungrounded conductors. Take a look at 110.4.

Chris

 

[drbond24]

SJO cable has a rating of 300V. Is this rating from conductor to ground or conductor to conductor?

The rating is just a limit you can't exceed. As you say, 277 single phase would be OK, but 277 three phase would put 480 volts between the conductors which would exceed your rating. Conductor to ground vs conductor to conductor doesn't matter; what matters is the voltage you are submitting the insulation to.

 

[iwire]

Frank just want to make sure you understand that 600 volt rubber cord is available.