View Full Version : Heavy duty Extension cord for welder?

10-10-2009, 03:53 PM
Hi, I want to know what guage extention cord I will need to make up for my hobart stickmate welder it is 220v 50 amp at the wall. Any suggestions would be appreciated.

10-10-2009, 07:58 PM
Please anyone?

10-10-2009, 08:37 PM
10ga should do it.

10-10-2009, 09:28 PM
I would buy the highest rated extension cord I could find, in a length long enough to do triple what I think I need e.g. here in OZ (Australia) we use 240v 50-60Hz as our general mains supply, and I use a 20m 20A extension cord, as the common extension cord is rated 10A


10-10-2009, 09:55 PM
TheKid is right, you'll need 10 Ga wire. There are welder extension cords but they have male and female ends. I had a elec. hot water heater I replaced with an oil fired. It ran on 220. I bought some 10 Ga wire and a 220V 50 amp female plug at Home Depot. I wired the plug to the cord and tied it in to the heater line. It works good. You didn't say how you'll get to the power source. You'll need a 220V 30A breaker. If you have that you should be good. Be VERY CAREFULL if you have to tie the line in to your breaker box. If you know an electrician ask a favor. If not, shut everything in the house off and shut the main breaker. Check for voltage and connect the wires. When you turn the power back on stand off to the side of the box when you throw the main breaker back on. Always keep in mind "electricity is not your friend". Good Luck

10-10-2009, 10:48 PM
Thanks Every one, I have a 220 50amp breaker in the laundry room which is what hobart calls for. It sounds like 10 guage with a male end and a female end should work. you guys have to be the freindliest forum I have ever been on.

Thanks again,

10-23-2009, 09:43 AM
10 Ga. will likely operate the equipment just fine, However, bear in mind that the 50 amp circuit breaker is meant to be the weak link in the power chain. A 10 Ga. cord is rated at 30 Amps. So .... If something were to go terribly wrong, the 50 Amp breaker will open and save the day. But, if things just get a little overloaded the 10 ga. 30 amp cord is going up in smoke. I don't mean to be pessimistic, but better safe than sorry. If you are the worrysome type, reduce the breaker to 30 amps, or better yet, Make a 6 Ga., 50 amp extension cord ($$$), then you will not be able to overload the cord.

10-23-2009, 10:06 AM
Unless he is superman, a 6ga extension cord will be unmanageable.

10-23-2009, 11:40 AM
Superman, that's funny, I use a hand truck just to move the welder around the shop. I used 6g to wire the breaker and had to use the big vise just to make the final bend for inside the breaker panel box. I think I'll live dangerously and try the 10g. Also I don't think I can afford any more 6g @ $2.00 a foot.

10-23-2009, 12:48 PM
Superman, that's funny, I use a hand truck just to move the welder around the shop. I used 6g to wire the breaker and had to use the big vise just to make the final bend for inside the breaker panel box. I think I'll live dangerously and try the 10g. Also I don't think I can afford any more 6g @ $2.00 a foot.

I don't think I would worry about it either, although the point is a valid one. I don't generally leave my extension cords plugged in when I am not using my welder, so hopefully I would notice a catastrophic event and unplug it. Even my Miller Thunderbolt says you need a 50A breaker, but it never even throws the 30A dryer circuit I plug it into even when I cranked it all the way up to cut steel with it. It would take a few minutes at least for it to get hot enough to melt before that 50 amp breaker threw. When you think about it, most extension cords are plugged into outlets with breakers larger than the rating of the cord. Otherwise you could only plug in one thing on that circuit.

I made my cord from a 10ga RV extension cord I got at Harbor Freight by replacing the ends.

10-23-2009, 01:14 PM
Thanks Trikeman,
That's really comforting, because I think my Hobart Stickmate is basicly the same thing as a Miller Thunderbolt according to the manufacturers photos anyway. I would be using my dryer outlet as well but the people at tractor supply(place of purchase) said that my house would go up in flames like the Hindenburg if I Didn't use the proper breaker(I still haven't figured that one out) but life is merry, life is good.

10-23-2009, 03:29 PM
Prolly why I don't ask for advice at TSC :1eye: Good prices though, which is why I bought my Hobart 140 there when I first got into this. I have always gotten good advice from the guys on the Hobart Weldtalk forum, and the Hobart engineers claim the Thunderbolt and Stickmate are the same under the covers.

01-05-2010, 12:54 AM
It depends on how far away you are from the breaker box / outlet and how often and how long you are going to weld.

I always add an extra gage or two when wiring for 220 volt.

10 gage might be OK.....but if you are say 20 feet or more from the main box, then I would recommend 8 or 6 wire. It does not hurt to have the extra ability of the wire to handle higher amps and for the longer distance the lower gage wire will allow for a cooler wire when running higher amps. Lowe's sells a nice 8 gage extension cord type cable that is very flexible and very good for setting up an extension cord for a 220 v single phase welder. About $1.27 per foot.

I've seen folks wire up an outlet for welding and with 10 wire, the wire was getting pretty warm. 10 is the minimum but I would still recommend going with 8 or 6 wire.

Better safe than sorry.

01-05-2010, 11:25 PM

I have been using a 10GA x 60' extension with my StickMate 220 AC/DC stick welder for over a year now with no worries.


01-06-2010, 03:45 PM
On your welder data plate it should say the FLA (full load amps) and that will determine what size wire you SHOULD use. 10GA is only good for 30 amps according to the NEC (National Electrical Code). Then you have to take in consideration voltage drop. But welding thin tube, voltage drop may be helpful. Voltage drop means how much the voltage drops for how far you have the power supply to the welder. if you use a 100' extension cord there could be more drop then if you plug the welder in to a dedicated outlet for it.


I have been using a 10GA x 60' extension with my StickMate 220 AC/DC stick welder for over a year now with no worries.


01-06-2010, 09:52 PM
The National Electrical Code allows you to derate the current for a welder if it has a duty cycle less than 100%. I dont remember the formula off the top of my head, but its Article 630. I think 30 Amp #10 wire is plenty for what we do here if you are using a 240v welder. I would not wire a 240 outlet with it, but an extension cord is something else. Zobman is right, its usually excessive voltage drop that concerns me more.

The deration factors are found in 630.11a (a table). At 20% load factor, which most of our welders are the multiplier to get the current for determining the wire size is 0.45. In other words if the nameplate current is 50A you only need 0.45x50Amp = 22.5Amp wire. Don't trust me on it - look it up. No sense in scaring the troops needlessly.

01-06-2010, 10:19 PM
In case you are wondering about why this is so, the wire ratings are based on how much heat the current puts into the wire. A device like a home welder puts in a lot less heat than something that runs continuously because it is always cycling on and off, allowing the wire to cool in between cycles. Breakers, on the other hand will throw fairly quickly, since when you design them, you never know what duty cycle the equipment has.

01-09-2010, 11:04 AM
I had a similar concern when I got my welder 25 years ago. I am an electrician with 36 years of experience.

10 gauge wire will do it, but the bigger problem will be the plugs. Electrical circuits always fail at the connection. Be very careful where the extension cord plug connects to the welder's factory cord. Make very sure that there is nothing flammable anywhere near it. When you use it for extended periods, you will see that it will get hot. If the connection deteriorates over time, it will get hotter.

My solution was to add longer leads to the welder. I have 40 feet of cord on it, so it doesn't matter that the welder is not near where I'm welding.

If you really want to be safe, rather than just plugging in to the extension cord, replace the factory cord on the welder with a long enough 10 gauge cord to get to where you want to plug it in.

01-09-2010, 10:22 PM
And a quick note on the length of the cable.
If its too long dont leave it coiled up tight whilst in use as it can get hot enough via induction to melt the insulation and catch fire.
Dont ask me how I know. It was very impressive. :innocent: SWMBO was not amused