Recept Wiring

[Alwayslearningelec]

Ok if I have (4) 20A duplexes spaced about 110' apart being run in conduit and the homeruns must in #10(THHN). How do I know/calculate if #12's would be ok from duplex to duplex? I know there must be a distance where #12's will not be sufficient.

They are being fed from a 120/208 panel and a 20a circuit breaker.

THANKS VERY MUCH

 

[jumper]

If you are referring to limiting voltage drop, in general not a NEC requirement, use the free calculator here, second link from the bottom.

http://www.mikeholt.com/freestuff.php?id=freegeneral

 

[infinity]

Do you know the actual load? Otherwise a VD calculator is kind of usless.

 

[jumper]

Do you know the actual load? Otherwise a VD calculator is kind of usless.

True. I forget that I worked mostly under a different set of parameters than many.

Unless a circuit was designated to a known load, I was ordered to make all general purpose receptacle circuits sized for full bore: full amperage at full voltage.

 

[Alwayslearningelec]

Do you know the actual load? Otherwise a VD calculator is kind of usless.

(4) 20a recpt being fed from a 20A breaker.

 

[Alwayslearningelec]

If you are referring to limiting voltage drop, in general not a NEC requirement, use the free calculator here, second link from the bottom.

http://www.mikeholt.com/freestuff.php?id=freegeneral

This is what it gave me.

 

[jumper]

This is what it gave me.

Are these general purpose receptacles in which you want 20 amps at 120v or is there a known load at each one?

 

[charlie b]

Do you know the actual load?

(4) 20a recpt being fed from a 20A breaker.

That doesn't answer the question. You can certainly calculate this as though you had a single load of 20 amps at the end of a 400 foot run. I see that you did, and that the results were not satisfactory. But that is not an accurate model of the installation.

For starters, what will be plugged into the receptacles? If you don't know, then I think it sufficient to assume that (1) The total load is 16 amps (80% of 20), and that (2) It is shared equally amongst the four receptacles. Therefore, you can model a 16 amp load that is 100 feet from the source, a 12 amp load that is 200 feet from the source, an 8 amp load that is 300 feet from the source, and a 4 amp load that is 400 feet from the source. If you do that, then the numbers are not as bad. I ran the numbers, and got from 5-8% with #12 AWG, and 3-5% with #10.

 

[Alwayslearningelec]

Are these general purpose receptacles in which you want 20 amps at 120v or is there a known load at each one?

No known load. 20AGP

 

[Alwayslearningelec]

That doesn't answer the question. You can certainly calculate this as though you had a single load of 20 amps at the end of a 400 foot run. I see that you did, and that the results were not satisfactory. But that is not an accurate model of the installation.

For starters, what will be plugged into the receptacles? If you don't know, then I think it sufficient to assume that (1) The total load is 16 amps (80% of 20), and that (2) It is shared equally amongst the four receptacles. Therefore, you can model a 16 amp load that is 100 feet from the source, a 12 amp load that is 200 feet from the source, an 8 amp load that is 300 feet from the source, and a 4 amp load that is 400 feet from the source. If you do that, then the numbers are not as bad. I ran the numbers, and got from 5-8% with #12 AWG, and 3-5% with #10.

THanks very much, that was really good info. I appreciate it very much. Thanks everyone.