use a #12 ground in a conduit with #10's ?

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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
200 feet underground plus 50 more feet inside. I will use #10 for a 20 amp circuit because of the distance. To cut cost and space, is it acceptable to use #12 ground wire ? Thank you.
How many actual amps is your load?

If you really have 20 amps and it's really 250 feet away, you need a #6 circuit to stay below 5% voltage drop

Or a #4 to stay below 3% voltage drop
 
Thank you ! I hadn't done a voltage drop calculation yet. You know where my question came from....every time I run a 6-3, I notice that small # 10 ground. I think, have I been missing something all these years ? But yes, I did the voltage drop calc, and see what you mean.
 

retirede

Senior Member
Location
Illinois
Can you clarify what you're getting at regarding the #10 being too small?

If you run a 60 A circuit with #6 conductors the egc can be a #10.
But if you have a 40A circuit and increase the conductors from #8 to #6 due to VD, the egc must be upsized proportionally - #10 is no longer compliant.
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
If you run a 60 A circuit with #6 conductors the egc can be a #10.
But if you have a 40A circuit and increase the conductors from #8 to #6 due to VD, the egc must be upsized proportionally - #10 is no longer compliant.
Yeah. It didn't make sense to me when I first read what Tom wrote. Then I read it 3 more times and realized what he was saying 👍👍
 

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I have to also run another underground circuit for this customer, this one is 100' underground plus 50' inside. I was thinking being able to use #12 for that 20 amp circuit, but the v drop requires at least a #10. I've been misjudging guessing wire size - distances recently.
 
Down size the wire and up size the amps. I know this sounds strange but if I upsize the amps to 30 and upsize the voltage to 340, I could use a smaller wire, correct ? Calculates to a # 8 Cu wire, not a # 6. I could install a small sub panel and use a smaller wire, correct ?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Where you coming up with 340V?
Down size the wire and up size the amps. I know this sounds strange but if I upsize the amps to 30 and upsize the voltage to 340, I could use a smaller wire, correct ? Calculates to a # 8 Cu wire, not a # 6. I could install a small sub panel and use a smaller wire, correct ?
 
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