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50 amps over 10AWG?

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ideal2545

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Hi Guys,

I've got an electrician who wants to run 75 feet of 10/2 gauge wire from a two pole 50 amp breaker to a subpanel and then down to a few 110v circuits. Does this seem okay. Everything i'm reading is saying that he would need to 6/3 from a 50 amp breaker. What do you guys think?
 
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pattenp

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You're correct with the #6 for 50 amps if the wire is NM-b. Plus you need the 3 conductor for the neutral to split it into 120V circuits.
 
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MrMark

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8 AWG THHN is rated for 50 amps with modern terminations (75 degree) but at 75 feet you should go with 6 to limit voltage drop.
 
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ideal2545

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He just told me via text, that the 10 gauge wire would be completely fine, and 3 wires in the ground is all he needs for the subpanel. I figured, maybe he wants to put in a grounding rod, but he won't answer that question. Definitely going to have fire this guy. He also already ran some conduit without a pullstring... the frustration is killing me.
 
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pattenp

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Where is this sub-panel? Is it in your house or in a detached shop/garage. The reason I ask is if the sub-panel is in a detached structure then you need the ground rod. If the sub-panel is in the same structure as the main panel then no ground rod is needed.
 
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pattenp

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Well then you do need a ground rod at the shop. Also if the sub-panel will have more than 6 circuit breakers you should use a main breaker panel. This is because a main disconnect is required if it takes more than 6 breakers to turn off all the power at the shop. And as said you do need 3 conductors plus a ground for the feed. Also I assume you are in the US.

ideal2545 said:
The subpanel would be in a detatched shop about 70-75 feet away from main panel
Click to expand...
 
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ideal2545

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Yep, all in the U.S.! Thanks PattenP I appreciate the info since it looks like I'll be doing this myself now
 
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pattenp

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Where I said ground rod, I should have said rods. Normally 2 are needed set at 6 feet apart. If you have any questions, ask before doing anything. I've seen people do things and then ask questions only to find out it was not to code.
 
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Speedy Petey

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Whoever suggest this is NOT an electrician. If he says he is then not only is he not an electrician, he also IS a liar.
 
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dtcooper

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joel63 said:
Not an electrician, but 50 amp breaker with #10 NM wire = NEVER!!!!
Click to expand...


Not exactly- 10 gauge IS allowed on a 50 amp breaker for dedicated Welder receptacle.. There are exceptions for overcurrent protection, in respect to welders.. So the word "Never" is a bit misused in your statement..

With that said, any attempt to feed your garage with # 10 on a 50 amp breaker for service out there, should be rejected..
 
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mrjaw14

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Maybe what you should do is get him to quote you a firm price for the work he's planning on doing, then get it in writing that if his job doesn't pass codes that he has to pay for the corrections. You'll be getting a lot more work for free LOL

He's stretching the single circuit rule for detached buildings. as soon as he tried to bust it up in 120v circuits he's violating code. any more than 1 circuit to a detached structure and you have to have proper sub-panel with a 4 wire feeder, ground rods, etc. That's before the #10 on a 50A breaker issue. Should be atleast 6 ga maybe 4 depending on the v drop calculations. he's either a *****, or thinks that you are.
 
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Mustang51js

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10 wire is only good for 30 amps, even in free air I don't think it would be rated for 50 amps but I don't have my code book to look it up for the free air part.
 
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Speedy Petey

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Mustang51js said:
10 wire is only good for 30 amps, even in free air I don't think it would be rated for 50 amps but I don't have my code book to look it up for the free air part.
Click to expand...
Not exactly.
#10 on a 50A breaker would be perfectly legal and safe in an air conditioning install.
 
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Mustang51js

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I just mentioned that because maybe the guy misunderstood him and was maybe thinking overhead installation,but still wouldn't be right.
 
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sberry

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There are a lot of ******* matches here about things but the consensus here is unanimous. As a matter of fact ran across one of these gems not too long ago.
 
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ideal2545

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So this morning I fired him. He had no plans to put in grounding rods and was planning to run ground from the main panel. (Which was of course, some lie or backtracking because he told me explicitly only 3 cables in the ground earlier.) He said that he, 'spoke to his buddies' and they all said that 50 amps over 10 gauge would be fine. I know for a fact that if you're going to split it between multiple circuits you for sure need 6, maybe 4 AWG (though maybe if its for a dedicated welder or A/C unit maybe you don't - debatable based on this thread haha).

Looks like I'm going to have a go at it myself. Unfortunely he already trenched and put in a 1/2'' conduit line and buried it WITHOUT a pullstring,
 
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pattenp

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So you do understand an equipment ground does need to run from the main panel to the sub panel, plus having the grounding electrodes (rods) off the sub panel at the detached structure?

He said he spoke with his buddies.... whow.. red flag.

The 1/2" conduit can be used for low voltage if needed.



*
 
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Sneeze357

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As much as I hate permits and inspections...stuff like this is why we have to have them. Still shouldn't cost $100 for a permit, but that's a whole 'nuther discussion...
 
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91bronc300

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dtcooper said:
Not exactly- 10 gauge IS allowed on a 50 amp breaker for dedicated Welder receptacle.. There are exceptions for overcurrent protection, in respect to welders.. So the word "Never" is a bit misused in your statement..

With that said, any attempt to feed your garage with # 10 on a 50 amp breaker for service out there, should be rejected..
Click to expand...


Is that because welders do not have the the high starting current like motors do?

I ask because just the other day I made a 50 foot 240 extension cord out of 10/3 and 50 amp plugs. I had been using some 8/4 for an extension cord (I know, 1 wasted conductor) but wanted to use it for something else and I had the 50 foot piece of 10/3 laying around. So I looked up online the ampacity for 10 gauge and it said 55 amps so I figured that's more than the 50 amp plugs so I took the plugs off the 8/4 and put them on the 10/3.

So I guess that means the 10/3 can only be used to the full 50 amp rating of the plugs if I use it with a welder?
 
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pattenp

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If the cord is for general use then #10 should be limited to 30 amps. In what use did you find that a #10 cord can be used at 55 amps?
 
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91bronc300

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pattenp said:
If the cord is for general use then #10 should be limited to 30 amps. In what use did you find that a #10 cord can be used at 55 amps?
Click to expand...


This chart right here: http://www.powerstream.com/Wire_Size.htm it says you can use 10 gauge for 55 amps if it's 'chassis wiring', whatever that is, but only 15 amps for power transmission. Then you say 10 gauge is only good for 30 amps for a general use cord. Then quoted above it says 10 gauge is good for 50 amps for a dedicated welder circuit only.

I guess I'll just use it until it melts :lol_hitti

I honestly didn't think any more of it after making the cord until I saw this thread.
 
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91bronc300

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Charles (in GA) said:
Some ID of the cord would help. SOOW or SOOJW, manufacture? Carol? Specs on the jacket of the cord?

Charles
Click to expand...

Says SJTW on it. I don't know the manufacturer. The outer jacket I would guess is PVC. The insulation on the actual conductors seems like a nice rubber.

sberry said:
Yes, its good for 50 for all but the 250 migs running wide open, screaming their guts out,,, which they wont do with 035/c25
Click to expand...

That is kind of what I figured. So is the reason you can use 10 gauge for 50 amps if it's a dedicated welder circuit but not for 50 amps if it's just a regular circuit because you're not having any surge currents such as starting a motor?
 
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