Required wire size for 220v welder

[KillNThrill24]

I've been researching online for a bit and have been finding all sorts of different answers that leave me scratching my head. Rather than go out and spend money I don't need to, or not spend the money I DO need to, I figured I'd ask you fine gentlemen (and ladies).

I picked this up, it's an Eastwood tig 200 digital. Yeah it's not the best out there, and has a 25% duty cycle, but that's plenty for my uses, not to mention I picked it up for $680 which is almost half price. The website calls for a 50 amp breaker (I included a screenshot from their site).

From the research I've done, I'm seeing it's required to run 8 gauge wiring on a 50 amp breaker for runs 50 feet and under. Is this accurate? Again, I just want to make sure I'm using the right gauge. I've run 220 wiring before so I'm not new to that side of things. Just never run wire for a 50 amp breaker before. Thanks for any and all help in advance. View attachment 881480

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[mike93lx]

Welders have an exception since they are intermittent use. 12 gauge is fine. Personally, i ran 10 thhn stranded in conduit to my plug.

This makes the plug "welder use only" and is completely acceptable.

This had also been covered here probably 100's of times. Some searching would answer your question

 

[850xpeps]

I ran 8 gauge for mine just because.

 

[KillNThrill24]

Welders have an exception since they are intermittent use. 12 gauge is fine. Personally, i ran 10 thhn stranded in conduit to my plug.

This makes the plug "welder use only" and is completely acceptable.

This had also been covered here probably 100's of times. Some searching would answer your question

I've been researching it for a while and came across numerous answers. I made sure to mention that in my original post.

Thanks for the info tho.

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[ATC]

I have 2 plugs for welders/plasma in my garage. A 30A plug with 10ga, and a 50A with 8ga. (I'm pretty sure...it's possible it's 6ga. I'd have to go look to be 100%) Both runs are under 20 feet.

I use the 30A plug for my 5hp air compressor too.

 

[sberry]

The manuals for those are notorious. I bet that is a max breaker. 12/50 may be legal but that would be single circuit in pipe, if using cable use 10. But,, I almost bet it's a 30A machine too.

 

[danielbuck]

I ran 10 gauge for my nema 6-50 outlets for use on the welder, compressor and bandsaw. One is 10 feet away, the other is 3 feet away from their the 50amp breakers.

 

[PoorOwner]

I think it is 8 awg in conduit but if using cable such as romex you need to use 6 awg for a 50 amp circuit. But a welder circuit can use thinner gauge. I used full gauge

 

[sberry]

You can use 12 in conduit for some 50A for welders.

 

[2oolhound]

The problem arises when some future user plugs a 50' welder extension cable into it to weld outside or to reach another location. (unless the welder is hard wired directly to the breaker panel so nowhere to plug the extension)

 

[sberry]

I am not quite sure I understand that but,,,, this is code legal under some circumstances. Been that way for a LONG time,,, well before the internet. If this was all a problem they would have changed/fixed it well before now.

 

[mike93lx]

The problem arises when some future user plugs a 50' welder extension cable into it to weld outside or to reach another location. (unless the welder is hard wired directly to the breaker panel so nowhere to plug the extension)

I worry about me, not what some guy down the road might do.

If it is code compliant AND I don't have concerns about my application, it is good to go in my house. What the next guy does is then his problem

 

[ssdave]

I worry about me, not what some guy down the road might do.

If it is code compliant AND I don't have concerns about my application, it is good to go in my house. What the next guy does is then his problem

Certainly one way to look at it. Another would be to design and build for what a reasonably competent and informed person expects, and not build booby traps for the next person to burn down their building with. That's what minimum electrical code is about.

A welder circuit that is de-rated under the welding chapter of the code has to be a dedicated circuit. Some inspectors interpret that to mean that the welder is hard wired into the circuit. Others require that the receptacle be restricted to the ampacity of the wire, and that can be wrong to plug in a welder. Others require that the circuit be labled clearly on the receptacle "for 50amp max, welding use only" and maybe with the ampacity for other uses also such as "40 amp max other uses".

The reason a welder circuit can be derated is that welders are rated for full current at a less than 100% duty cycle. The assumption (and it has held up in actual experience with installed welders) is that the duty cycle of the welder will cut off the use before the supply wires get hot enough to cause a fire. Wire sizing in code is about keeping heat down so fires don't start. That takes high amperage and time. The duty cycle of the welder limits the time.

I sidestepped all that in my recent shop. I bought 6 ga copper, and wired my 5 different 220 receptacles with that. Now, I can plug anything into those receptacles and not worry about the wire. Cost was pretty nominal as I had short runs to the panel.

An interesting aside on wire size: I always wire my air conditioners with 6 ga. I ran the calculations once, on the resistance loss and heat generation of smaller wires vs 6 ga. The resistance loss costs money in wasted power. The heat generation that results must be removed from the space by the air conditioner, thus increasing the load, and costing more power. When I calc'ed it, my payback was 5 months to pay off the upsizing to 6 ga copper from 8 ga. No brainer from a cost standpoint, and safer also.

Just because code will allow downrating a wire size doesn't mean you should.

 

[sberry]

I have actually talked to fire inspectors and been to a seminar or 2 about fire forensics. I asked my bud,,,, you ever see a house fire from a comp or welder primary wiring. He said,,, no. Seen them from use.
Now,,, as I mention, the minimum is for single circuit in pipe. Someone figured out a couple things about this, that it would short circuit or spike in the load before it would cause a problem. Second once that the wire is sized up the V drop and the heat takes a real nose dive.
I have welded with buzzers on 10 cable till they were glowing and the wire is barely warm. Wayyyyy beyond the rated duty cycle of the machine, way past what most hobby welders could ever do.
I am not saying that its bad to over wire but we don't need to insist that its wired up 3 code sizes either. I wire up a size on occasion,,, I don't usually do 2 unless its free.
The code and fire people have some logic behind all the requirements. I know it can be hard to except their expertise but they take it pretty serious. There has been 100 years of forensics, the materials have improved and peak amperage has dropped for the same machines since v has risen. Some allow the same wire at 208 as 240.
If its safe at 208,, and 220 its probably better at 240. Every once in a while there is a different spec wire, its listed in the manuals. Many of these modern machines now allow 14/30,,, really not a fan and its got to be piped. Once the wire is sized up to 12 the performance is improved some, quite a bit especially with longer wire and wide open which is typical with the small machines.

 

[driz]

When I did mine I went straight to the electrical supply with a diagram and measurements. Told counter guy what I had. Nd he set me up on the spot. No worries wondering or rear kissing . Ghost guys know the codes , so simple


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[NC Rick]

So the wire size is what is protected by the breaker right? I don’t know anything in the NEC which allows derating wire size for a breaker size. Heat gain in conduit would be more tolerable. Cost savings in wire gauge seems most important in longer runs which is just the time I wouldn’t want smaller wire.

My inverter TIG will run on 120 20a and still do pretty well. It is wired to a 60 amp breaker with 8 gauge wire.

 

[anndel]

I've installed 8 ga in mine though specs and NEC called for 12 ga.

 

[AA/FC]

Sure, there may be an exception for welders, but who knows what someone might plug into that outlet in the future. I always size the wire according to the breaker. Usually these 240 volt welders come with a 50 amp plug, therefore you need a 50 amp receptacle. Both of my 50 amp receptacles are fed with #8 copper THHN from a 50 amp breaker. Other than saving money on the cost of wire, why would you skimp on your electrical system? Especially in your own house an/or shop....

 

[NC Rick]

Oops, I lied, I just checked. I ran 4 gauge. My “new” welder only takes 40 amps max.... I only have a 10 ft run.

 

[sberry]

So the wire size is what is protected by the breaker right? I don’t know anything in the NEC which allows derating wire size for a breaker size. Heat gain in conduit would be more tolerable. Cost savings in wire gauge seems most important in longer runs which is just the time I wouldn’t want smaller wire.

My inverter TIG will run on 120 20a and still do pretty well. It is wired to a 60 amp breaker with 8 gauge wire.

Longer is,,,, subjective. The code allows 85 ft 12 to a buzzer,,,, any shorter,, any bigger and it is better and adds margin for safety. Sometimes upsizing isn't a big deal, from 14 to 12 isn't, from 14 to 6 is. I use 10 a lot. Its a size bigger than is needed and it gives them a boost by reducing drop to insignificant.
I have wire in stock, not a big deal and normally use 10/30 for the small machines, they are small and gives them all the help they can get. I have a couple 10/50 too,,, 3 ft of wire doesn't make for much drop.
There are really only a couple places in all this wiring that the breaker actually protects the wire for thermal. Mainly in general use circuits where someone can come along and plug multiple appliances in to it. Thermal is normally the function of applied load, its often from the internal additional protection within the appliance.

but who knows what someone might plug into that outlet in the future.

I own a lot of stuff. Not 1 single thing I own do I plug in to a welder circuit besides a welder. I do have several and do have 1 or 2 with heavy wire for 250 class feeders. I do mark the cover as to what wire is in it but its not a legal requirement.

 

[sberry]

My inverter TIG will run on 120 20a and still do pretty well. It is wired to a 60 amp breaker with 8 gauge wire.

if it comes with a 50 plug it needs to be limited to a 50 breaker. The adapter for the dvi does have additional protection in it for these machines,,, but still,,,
These dvi are also way smaller input, they can go on 30A. I just wired one. The guy is thrifty,,, ha,,, but it was 50 ft, I up it to 12 wire and its got 30 on it.
I do agree about coming up a size from the minimum,,, I usually write this for some understanding of the fundamental nature of these circuits and to point out what is legal. The minimums are adequate but,,,, duty cycle does often get exceeded and the little machines are wide open. My small feeder generally is on high,, gets turned down once in a while.
The buzzers that allow for 12 are at rated output,, 225A at 20 percent. Its super rare to turn one up that far and they pull closer to 40 under normal use than 50 so its not such a stretch.

 

[ssdave]

So the wire size is what is protected by the breaker right? I don’t know anything in the NEC which allows derating wire size for a breaker size. Heat gain in conduit would be more tolerable. Cost savings in wire gauge seems most important in longer runs which is just the time I wouldn’t want smaller wire.

My inverter TIG will run on 120 20a and still do pretty well. It is wired to a 60 amp breaker with 8 gauge wire.

Try Article 630 NEC, specifically for welders:

 

[ssdave]

The reason to upsize the conductors is that contrary to what most guys that do the minimum use as their rationalization, they will not own the circuit forever. And the next guy won't be smart enough to guess what the original intent and construction of the circuit was, along with it's limitations.

If I install a 50 amp receptacle, and feed it with a 50 amp breaker and 12 ga wire after derating for a welder with 50 amp rating at 40% duty cycle in accordance with Table 630.11, what is to keep someone from plugging something into that circuit in the future that will continuously draw 50 amps. Say, they decide to use the garage for a workspace, and plug an electric furnace into the circuit? At that point, the continuous current draw can easily overheat the circuit, without the circuit breaker tripping.

That welder chapter was intended to cover industrial welding installations, not home garages. For the cost of upsizing the wire to match the rest of the current ampacities, I'd not take that chance.

But, if you insist on being that cheap, code will allow you to take a chance.

 

[sberry]

The furnace does not come with a plug, it is hard wired. Also, if it was 40 percent it needs a wire larger than 12.

 

[PoorOwner]

Pretty easy to take out the receptacle and breaker when you sell the house. Whatever people want to do is their problem.

 

[sberry]

The rv.uses a different plug.
If it's wired for 50 at 40 percent it needs a bigger wire.

 

[KillNThrill24]

Well this turned into a little more than I was expecting. Thanks for the info so far tho. Sounds like the 8 gauge is probably the safest bet. The outlet will be strictly welder (I'll have others setup for the compressor and lift down the road), but my safety is not something I play around with. And if I do need an extra 240 and I'm not using the welder, it will be available and wired for other applications. I'll continue to read up on the replies tho. I knew you guys would be able to settle this for me.

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[sberry]

Something else to note,, as of this point,,, but when this kind of thread comes up not 1 master electrician arguing this point. All.diy types.
If this was a problem the code would address it, they wouldn't leave it to "chance". They can't prevent every dumb thing someone might do but there is usually some protection for it and some margin. Again, there are some conditions to using the minimum.
My neighbor is a master, holds about every qualification you can get. Can have any wire for free, still has the same 10 cable wired to his welder outlet he put in 35 years ago. If it was unsafe he would change it.
The code can't stop someone from putting a plug on a machine not sposedly to be on it, then plugging it in to a circuit not sposedly to be used. But one would have to work at it to overheat the legal 10 cable. An egineer or other sparks here may be able to tell us what might happen to a 12 in a pipe with a 50A continuous load applied. I would say short circuit before fire, might burn a connection open, might trip up the breaker on thermal but seems like the small wire might be a limiter? I am not sure, never seen it happen.
We had a case here,, the guy had his bud the "electrician" from work,,, wire up a 7.5 comp. Used a 12 cable, the poster here saw it when moving, ran like that with regular use, 18 years.

 

[sberry]

Well this turned into a little more than I was expecting. Thanks for the info so far tho. Sounds like the 8 gauge is probably the safest bet. The outlet will be strictly welder (I'll have others setup for the compressor and lift down the road), but my safety is not something I play around with. And if I do need an extra 240 and I'm not using the welder, it will be available and wired for other applications. I'll continue to read up on the replies tho. I knew you guys would be able to settle this for me.

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What "other" applications would you be using this welder circuit for? Recept is only motor rated to 3hp, most other equipment above 30A is hard wired. The 8 is good, even great. If it's in pipe it's good for any welder made comes with factory cord and plug. Really is even cable for practical purpose, not many at home run a 252 with 400A gun, special gas, 045 wire in spray building trailer frames on assembly line.

 

[sberry]

Most of the RV guys I've seen have a box full of adapters to allow them to plug into anything. It's hard to defeat someone determined to short circuit original intent!

They do not or should not be adapting a 4 wire rv to a 3 wire welding.

 

[sberry]

If this is a 14/50 (rv) recept it's not allowed to be under wired, welder or not.
As I mention,, it's not a bad thing to use more than is needed but one doesn't have to and I only make this point to promote a little understanding vs a simplistic version,, well I wired mine with 6,,, well not much to really learn from that.
This has some of the most basic fundamental theory of safe operation and instalation involved. Might be a great idea to see what there is to learn from it vs trying to prove it wrong which is about as kindly as I know how to say it.
If this was a problem minds greater than our own would work on it, as far as I know not even a code proposal they even vote on.
As for the rv, any other kind of circuit they plug in to with 50 will trip the premise circuit breaker. A welder.receipt which is 240 is really the only one allowed to have under sized wire.

 

[KillNThrill24]

[emoji481]
What "other" applications would you be using this welder circuit for? Recept is only motor rated to 3hp, most other equipment above 30A is hard wired. The 8 is good, even great. If it's in pipe it's good for any welder made comes with factory cord and plug. Really is even cable for practical purpose, not many at home run a 252 with 400A gun, special gas, 045 wire in spray building trailer frames on assembly line.

Honestly, probably none. Especially when I'm going to have a compressor on its own run, and a lift on its own run. But I'm a safer rather than sorry type of person anyway, and I'd rather not "set a trap" for lack of better terms, for the next guy should I ever move. I just wanted a little clarification from all the things I read from a Google search. I have no problem spending a few bucks more and running the 8 gauge to ensure I never have an issue, and neither does the next person.

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[ssdave]

I think you're on the best track; 8 ga will match the breaker, regardless of what the load is.

We're arguing minutae here; I think we all agree that unless there's a compelling reason to undersize the wire, it's best to just wire it conventionally. We're also talking different comparisons, sberry talks about individual wires in conduit, vs cable and no conduit, and we're all talking hypothetical welders, we don't even know what the current demand is on yours, only the manufacturers breaker recommendation. The difference in price for 50 feet of wire between 8 ga and 10 is about $25.

My intention was never to advocate your wiring it with 6 ga. My recommendation is just to go with the conventional wiring ampacity, not the derated dedicated welding circuit one. I went with the 6 ga, as I had leftover from my AC, and my 220 boxes are within feet of the panel, so the extras worked out for them. My welder is also recommended for 100 amp breaker, and a high duty cycle. I doubt I'll ever run it there, but that is what it is designed for. The previous owner was running it on a 3 wire dryer plug pigtail, spliced into the machines cord with black electrician tape and twisted together connections, no mechanical connectors at all.

 

[nelstomlinson]

Just run some 6 gauge romex like you would for your kitchen stove and be happy. Later on you can plug in a big air compressor or something to that same circuit. You won't waste energy on voltage drop, and you have some future flexibility.

 

[AA/FC]

I own a lot of stuff. Not 1 single thing I own do I plug in to a welder circuit besides a welder.

Congrats! Feel free to wire your outlets however you want..... and so will I.

 

[AA/FC]

Something else to note,, as of this point,,, but when this kind of thread comes up not 1 master electrician arguing this point. All.diy types.

Including yourself.

My neighbor is a master, holds about every qualification you can get.

I have three very close friends of mine who are all hold a masters license. One of which "supervised" me when I was wiring my shop for both welding outlets. He was the one who told me "no reason to skimp, buy the right ****". 50 amp receptacles, #6 copper THHN, 50 amp breakers. Like I said, sure there may be an EXCEPTION for welders, but that doesn't mean you HAVE to under size the wire. You can certainly feel free to wire it correctly, too.


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[NC Rick]

I think you're on the best track; 8 ga will match the breaker, regardless of what the load is.

We're arguing minutae here; I think we all agree that unless there's a compelling reason to undersize the wire, it's best to just wire it conventionally. We're also talking different comparisons, sberry talks about individual wires in conduit, vs cable and no conduit, and we're all talking hypothetical welders, we don't even know what the current demand is on yours, only the manufacturers breaker recommendation. The difference in price for 50 feet of wire between 8 ga and 10 is about $25.

My intention was never to advocate your wiring it with 6 ga. My recommendation is just to go with the conventional wiring ampacity, not the derated dedicated welding circuit one. I went with the 6 ga, as I had leftover from my AC, and my 220 boxes are within feet of the panel, so the extras worked out for them. My welder is also recommended for 100 amp breaker, and a high duty cycle. I doubt I'll ever run it there, but that is what it is designed for. The previous owner was running it on a 3 wire dryer plug pigtail, spliced into the machines cord with black electrician tape and twisted together connections, no mechanical connectors at all.

Well said and solid advice.

 

[toplessHO]

why skimp over a few pennies in the cost of wire
50amp outlet/50 amp breaker
50 amp wire.
If the duty cycle changes when you upgrade,are you going to go back and change the wire?
#12 wire on a 50amp breaker isnt smart.

 

[sberry]

I didn't say anyone had to under wire it,,, but they don't have to over wire it either.

Including yourself.

While I don't hold a license I do work with this and am pretty well versed in it especially in regards to welding equipment,, and shop equipment of this nature. There are a few masters on this forum would not have a problem coming on here and pointing out I was FOS if it was the case.

 

[sberry]

I went with the 6 ga, as I had leftover from my AC, and my 220 boxes are within feet of the panel, so the extras worked out for them. My welder is also recommended for 100 amp breaker, and a high duty cycle. I doubt I'll ever run it there, but that is what it is designed for

I would likely do what you did too with left over wire, no reason at all not to. But a couple minor things,,, its 240V and, you can run 100A on 6 for some machines but it should be hard wired. (not 50A recept) (not saying I havnt done it) but that's the rule.
Another minor thing,, or not so minor,, but if we are underwiring a larger machine, truly under wiring it then match the wire to breaker. For example, some 100A input units call for number 4 or 2,, they will run on 6 but if we use 6 limit the breaker to 60. If we use the listed breaker we need to use the minimum size listed in the manual.