Voltage drop conductors

[fjohn49]

When conductor size has been increased for voltage drop, such as for pole lighting, the conductors may be too large to terminate on a breaker or lighting control unit. i.e. #8 conductors on a 20 amp breaker or relay that is rated for a maximum #10 conductor.
In the situation I have, the load is 14.5 amps at 480 volts single phase. I want to install #12 wire from the breaker, to the Wattstopper relay's line side and the #8's from the pole's on the load side. The length of the #12 wire is under 48". I cannot find anything in the NEC that prevents this, however another electrician insists this is against code and proper installation practices.

 

[roger]

Re: Voltage drop conductors

This is perfectly acceptable. When compensating for voltage drop the overall resistance of the conductor(s) is the only concern. You can start with large wires and end with small wires, or you can start with small wires and end with large wires. Regardless of either situation, the terminations can be reduced to the size wire that would handle the load.

Roger

 

[Nick]

Re: Voltage drop conductors

You won?t find anything because it is not in the NEC. If your conductor is properly sized I see nothing wrong with what you describe. The voltage drop on the short section of #12 will be minimal.

 

[bill addiss]

Re: Voltage drop conductors

Roger,

You beat me to it...

fjohn,

In instances where disagreements like this occur it is sometimes useful to ask the person where you would find this Code Rule.

Bill

 

[bill addiss]

Re: Voltage drop conductors

Nick too?

Boy you guys are fast...


Bill

 

[roger]

Re: Voltage drop conductors

I appologize Bill. By the way we're starting to warm up here in the mountains of NC, I hope you all are too.

Roger

 

[fjohn49]

Re: Voltage drop conductors

Thanks, I did ask where he picked up his information. His reply was, "I guess I've been doing it wrong for 20 years!" I was looking for something to confirm that the only concern was the overall impedance and voltage drop.

thanks again

 

[dereckbc]

Re: Voltage drop conductors

fjohm49. No problem increasing conductor size to control voltage drop, but you must increase EGC size to meet the requirements of 250.122(B).