If my wire is rated for 600V, would this be considered its line to neutral rating? Or would it be the line to line rating?
Would that mean that I could use a 300 volt rated conductor on a 480Y/277 volt system?The conductor alone can handle 600V so theoretically if you had a 1200v single phase load then each conductor could carry 600V and you would be fine.
That is what I think. Each conductor is only seeing 277 volts so why not if it is rated 300 volts. It doesn't say rated for a 300V system. Maybe I am wrong but that is what I always thought.Would that mean that I could use a 300 volt rated conductor on a 480Y/277 volt system?
I don't disagree that it should technically work, but it would be violation of 110.4.That is what I think. Each conductor is only seeing 277 volts so why not if it is rated 300 volts. It doesn't say rated for a 300V system. Maybe I am wrong but that is what I always thought.
So I could use it for 277 but not 480? That seems odd to me. If the insulation is rated 300V then it should be able to handle 480V Obviously something else I can't understand.I don't disagree that it should technically work, but it would be violation of 110.4.
No, I think we agree that it works technically speaking: It should withstand the phase-to-ground voltage because that is only 277V. And when you have two insulated conductors, their insulation value sums, so they should be able to withstand 480V between phase-to-phase.So I could use it for 277 but not 480? That seems odd to me. If the insulation is rated 300V then it should be able to handle 480V Obviously something else I can't understand.
So the installed equipment must match the voltage of the circuit which is defined as:Voltages. Throughout this Code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected.
Between the two of these this reads to me that any equipment must be rated for the phase-to-phase voltage. 300V wiring on a 480V system would not meet that criteria even if I believe it would work.Voltage (of a circuit). The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned.
You are wrong.I may be wrong but this is how I understand it:
If you had a car that claimed it could protect the driver in collisions up to 50 MPH, it would be rational to assume that you would be OK hitting a brick wall at 50 MPH but it would NOT be rational to assume you would be safe if you had a head on collision with another vehicle and both vehicles were traveling at 50 MPH. That would be the equivalent of hitting a brick wall at 100 MPH.
Aside from the voltage you see on each conductor, you also have the phases to consider which is why you can't use 300V rated cable on 480V circuits. It's the same effect as the head-on collision.
You are wrong.
A car going 50 mph hitting a stationary car of equal weight and crush characteristics is like hitting a brick wall at 25 mph.
Two identical cars hitting head on at 50 mph each is like two cars each hitting a brick wall at 50 mph.
Imagine the two cars hitting opposite sides of the same brick wall. Now remove the wall and nothing changes.
No, I think we agree that it works technically speaking: It should withstand the phase-to-ground voltage because that is only 277V. And when you have two insulated conductors, their insulation value sums, so they should be able to withstand 480V between phase-to-phase.
That said: 110.4 says
So the installed equipment must match the voltage of the circuit which is defined as: Between the two of these this reads to me that any equipment must be rated for the phase-to-phase voltage. 300V wiring on a 480V system would not meet that criteria even if I believe it would work.
It is not impossible, but it would be a very odd system in which the line to ground voltage is greater than the line to line voltage, so we are OK on that.