Amperage Reading

[jap]

If you have a parrallel Feeder. (2 conductors per Phase). If you take an amp reading on only 1 of the conductors on its phase, will it indicate the full load for that phase ? or must it be multiplied by 2 to be correct?

If the current on the single conductor on a phase does not represent the full load for that phase, how does the current divide equally between the 2 conductors?

 

[480sparky]

You could read one conductor, double the reading, and have a reasonable amperage reading for the circuit, but to accurately take a reading, you need to clamp on to both conductors at the same time.

The current divides itself pretty much equally because electrons don't care which conductor they travel through. Some go into one, some the other. It's not like they say, "Hey, let's all go this way, gang!"

 

[jap]

Thats another part of my question.

Is there ever an instance (Since they dont say,"Hey guys lets go this way or that") that a single conductor of a paralleled phase could be carrying more amperage than what it is rated for?

 

[480sparky]

Thats another part of my question.

Is there ever an instance (Since they dont say,"Hey guys lets go this way or that") that a single conductor of a paralleled phase could be carrying more amperage than what it is rated for?

Certainly.... in a short circuit.

Another instance might be if the other conductor becomes disconnected.

 

[macmikeman]

Thats another part of my question.

Is there ever an instance (Since they dont say,"Hey guys lets go this way or that") that a single conductor of a paralleled phase could be carrying more amperage than what it is rated for?

You bet, and thats why the critical need to be very close to each other in length and similarity.

 

[jap]

I've opened up a 600 Amp Fused disconnect before where 1 of the conductors of a paralleled phase was glowing like the sun, it was so hot.
At first thought, one might think it was getting so hot because that particular conductor, was a loose connection, where as in hind site it could have been that the other phase conductors actually had a bad connection, leaving that one conductor to try and carry the full load for that phase.

 

[charlie b]

Is there ever an instance . . .that a single conductor of a paralleled phase could be carrying more amperage than what it is rated for?

It must necessarily happen 100% of the time!

Current will flow in two or more parallel conductors in inverse proportion to the impedance in each conductor. That is, the wire with the least resistance will get the most current. If the two conductors have about the same impedance (which they should, since we are suppose to make them match each other), then their currents will be about the same. But no two wires are "exactly" the same, so the currents will never be exactly the same. They may be so close that your measuring instrument cannot tell the difference.

If the impedances of two parallel conductors are very much different, such as might happen if one has a bad connection, then there will be a big difference in the currents in each conductor.

 

[jap]

Interesting,,,,,, Thanks. JAP