Mixing AWG size?

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stgeorge

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Can you use a 10-AWG neutral on a 3-pole 30A circuit wired with 8-AWG?? So the end result would be Twist-lock receptacles would have 8-AWG hots and a 10-AWG neutral on said circuit..You can use 10 or 8 so... Can you mix different wires sizes on a circuit if both sizes are ok in there own right???
Thanks in advanced.
 
But your EGC would have to be a #8, see 250.122

Roger
 
iwire said:
See 250.122(B), it will have to be 8AWG. :smile:
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I agree with Roger and Bob, #8. Since you've increased the size of the ungrounded conductors the EGC would have to be proportionately increased too.
 
The reasoning behind this is if the wire size is increased for voltage drop considerations, the EGC shall also be increased to keep the ground path resistance low also.
 
hillbilly1 said:
The reasoning behind this is if the wire size is increased for voltage drop considerations, the EGC shall also be increased to keep the ground path resistance low also.
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So to make it clear: If I pulled a #6 wh, red, black and a #10 green and put it on a 50a breaker it would be compliant, but if I If I pulled a #6 wh, red, black and a #10 green and put it on a 40A breaker it would not be compliant? what if it was a 30A breaker?

~Matt
 
TOOL_5150 said:
what if it was a 30A breaker?

~Matt
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Basically, the EGC would have to be the same size as any ungrounded conductors supplying circuits up to 30 amps.

Yeah, the article section needs some work but, that doesn't change the requirement (as worded) at the present time

Roger
 
I think it was worded a little different in a previous code to reflect the voltage drop issue, but in the 05' code it does not mention it. It just calls foe the EGC to be upsized proportionally to the conductors.
 
There might be another reason for upsizing the EGC proportionately to circuit conductors: In case someone ever decides to use OCP closer to the conductor's the-heck-with-the-voltage-drop ampacity.
 
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