# what size wire for a 100 amp subpanel 200' away from the main service?



## zss42002

i have a 200 amp service wondering what size wire i need for a 100 amp subpanel 220' away from the main service? also what size equip. ground. i got with a 5% vd 1/0 cu and 3/0 at 3% drop. i also got 3/0 al at 5% and 300 at 3
%. this seems a little high. i was figuring to use the 5% drop and do a 3/0 al with a number 2al ground. does this sound right??


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## Dennis Alwon

The sub panel is 100 amp but what is the calculated load. If you are looking for the wire size for 100 amps at 240 then 2/0 alum. would work. For copper you need #1.

For the EGC then look at T. 250.122


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## william1978

^^^^What Dennis said.


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## Dennis Alwon

Remember there is no NEC requirement to wire for VD. It is a good idea and good design but not required.

BTW, I believe the same wire sizes are good for 208, 3 phase also.


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## zss42002

Its for a garage at my friends house there is no calc. Load as of yet but there will prob be 15-20 lights a compressor, mayb a 220v motor for a lift. And acouple outlets for grinding wheel and stuff like that but nothing major. So 2/0 would be plenty for this?
As for the egc do I have to take into acount the length and bump it up a couple sizes like the feeders?? Or just go with the 100 amp size??


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## 480sparky

zss42002 said:


> Its for a garage at my friends house there is no calc. Load as of yet but there will prob be 15-20 lights a compressor, mayb a 220v motor for a lift. And acouple outlets for grinding wheel and stuff like that but nothing major. So 2/0 would be plenty for this?
> As for the egc do I have to take into acount the length and bump it up a couple sizes like the feeders?? Or just go with the 100 amp size??


If you increase the wire size, you must increase the ground size. 250.122(B).


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## Dennis Alwon

480sparky said:


> If you increase the wire size, you must increase the ground size. 250.122(B).


Good point


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## Dennis Alwon

Ken will calculate the egc for you for a few bucks.


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## Dennis Alwon

I think you would need a #4 copper EGC-- send Ken $10


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## 480sparky

Dennis Alwon said:


> I think you would need a #4 copper EGC-- send Ken $10



Man.... what a scheme.... get everyone on the forum to send me a ten-spot! I'm rich!


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## TOOL_5150

480sparky said:


> Man.... what a scheme.... get everyone on the forum to send me a ten-spot! I'm rich!


just as long as dinner is at your house!

~Matt


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## ampman

one million mcm


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## 480sparky

TOOL_5150 said:


> just as long as dinner is at your house!
> 
> ~Matt



Hey, if all 13,329 members sent me a 10-spot, I'd definitely have a shindig at my place. :thumbsup:


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## oldschool

480sparky said:


> Hey, if all 13,329 members sent me a 10-spot, I'd definitely have a shindig at my place. :thumbsup:


lets have a raffle

everyone who wants to put up ten bucks

pick one winner


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## nitro71

The more load, the more the voltage drop. Mike Holt has a calculator you can download.

http://www.mikeholt.com/technical.php?id=technicalvoltagedrop


#3 THHN\THWN copper is good for 100 amps at 75 degrees. 

With a load of 50amps at 240volts at 200' with #3 copper Mike Holts voltage drop tool says you have 2.1% voltage drop.


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