Welder Extension Cord

[eastexan]

I found a heavy extension cord where I used to live that someone had left behind. It had a 50amp receptacle on one end and a 30amp plug on the other for plugging into a dryer outlet. I have used it at times for welding projects away from my shop and close to my house.

Last May, I used the extension cord in welding some 3/8" plate to some 1/2" angle with 5/32" rod to make a weight box for the front of my tractor, and it all went fine.
But the other day, after reading about welding extension cords, I got curious and decided to open the receptacle end up and see what size wire was in there.
I was surprised to see that I had been doing all that welding with 12/3 with ground. Of course the neutral wire wasn't hooked up, but that extra wire in the cable made it fatter and look as though it had bigger gauge wire than it actually had.

But the bottom line is that it worked fine, and when I rolled the extension cord up afterward, I never noticed it being hot.
I guess the reason being that I took my time between rods in chipping slag and wire brushing and kept within the welder duty cycle, and nothing got overheated.

If I had known it was only 12 gauge wire, I probably would have never even tried it. I've used both my Idealarc and Thunderbolt on that cord and hope the machines weren't hurt in any way, but I think they're fine.

 

[J_J]

How much difference would the voltage make in the selection of wire gage? Is it not true that as the voltage goes higher, the gage of the wire could change to a smaller gage wire. For instance in Jacksonville, I read a voltage of 240 , so does that make up for any voltage drop caused by the gage of wire? The machine calls for 208V.

I don't care to argue about the wire size, but when someone puts up a chart with diameter of the wire, the resistance, open wire, covered wire, length, what good is the chart/tables?

You ask 5 electricians about what size wire, and you get several answers. You could use this, you can safely use this, You must use the wire only, etc.

Some of the cords specify 2 #8 with #10 ground, don't understand that either.

Yes, I see the 50 ft cords with #8, but with a 50 A plug, and I am guessing for safety, not capability.

What current should #8 wire carry, in an extension cord.

The cord to my plasma cutter has #8

Can I get away with plugging it into #10 wire. I have only been using it that way for about 8 years, but was I totally unsafe?

I have been meaning to measure the current on the #10 wire at my max plasma cutter setting, using a Fluke amp meter.

 

[Lightnsound]

Some of the sources being used to find the data are questionable. A copy of the NEC or a $14 copy of Ugly's is the way to go.

Ampacity is ampacity, regardless of voltage. The insulation on the wire must be rated at or above the voltage being used, but an amp is an amp and it doesn't matter what the voltage is when determining the wire gauge.

 

[Short Game]

I came into a bunch of 6 and 8 cable and built various extensions to give me options for my 220 needs.

This one comes straight from my panel and is where my welder used to be. I back-to-backed two outlets on a scrap of plywood. It was interesting to find that some Leviton outlets of various amp ratings were identical inside and only the way the slots were made in the plastic was different.

I inherited this setup and added a second 220 pattern. I run my welder on that 30 amp breaker and never trip it, even when the compressor fires off at the same time. It's on a 2X6 with a screw eye at the top for hanging it. The cable is 60 feet of 8 gauge. One of the plugs goes to my disc sander and the other to my next extension, with the welder and compressor plugged in there.

This is the latest one I built and is way handy.

Luckily I'm not in business and won't be getting stuff disallowed (yet). All the connection points are soldered and solid. I know it's all good, and that's good enough for me.

Most of the outlets were gotten from garage sales and thrift stores for fifty cents or a buck, as were the 6 gauge plugs.

 

[eastexan]

Short Game, looks like you have a real handy setup. :thumbsup:

 

[JB4310]

Well I can understand how this topic has caused some division.

I checked my Miller ac/dc machine today, I knew the power cord coming out of the box was fairly small, but was shocked to see it's only a 12/3 wire :confused2:

Says right on the front cover it requires 47.5 amps, so of course I wanted to do the circuit legit and have a 50 amp breaker with 6 gauge wire to the 50 amp outlet. So I guess you could safely use a much smaller extension cord, probably get away with a 10Ga if not going to far???

Like I mentioned I have a monster 50+ foot, 6/4 cable, I got it for free, but if I paid what it would really cost, I might feel kinda foolish finding out it is way overkill. Mine doubles as a whole house generator feed, so I do need the heavier cable. My genny now is 10kw and has a 40 amp breaker, so I guess that 6 ga cable could handle 12kw or maybe more generator.

JB.

 

[J_J]

I saw this wire gage chart, does it have any value?

.

 

[JB4310]

I saw this wire gage chart, does it have any value?

.

I don't know, But it shows 6 ga wire needed for 20 amps at 30 feet

This chart is at the other end of the spectrum from what you referenced before.

Maybe I'm not reading it right???

JB

 

[dstig1]

Every power tool/welder these days has a similar chart in the owners manual telling you acceptable extension cord sizes by length. Easiest thing to do is use that. It would be different for 120v vs 240V as the voltage drop would be worse on the lower voltage.

 

[MikeD74T]

.....Ampacity is ampacity, regardless of voltage. The insulation on the wire must be rated at or above the voltage being used, but an amp is an amp and it doesn't matter what the voltage is when determining the wire gauge.

Sorry, that's just plain wrong. A watt (=volts x amps) is always a watt , but an amp is only an amp at a specific voltage. Ever notice that the 13.5kv line that feeds your entire neighborhood is smaller than either of the 120v lines that feed your house? Same with a welder, the 12/10/8 guage power cord is much smaller than the welding leads. That's because your welding with 1/10th the voltage so a much bigger lead is necessary to carry the increased amps. Otherwisw how could you get 180 amps from a machine on a 40 amp breaker???
Wire charts assume the reader knows that the amperage numbers are all given for the same specific voltage. JJ's chart may be being presented out of context for a purpose. If this chart is for 12 volt automotive work it makes more sense. For example 30 amps x 12 volts =360 watts or .48 hp, whereas 30 amps x 120v =3600 watts or 4.8 hp. #6 wire x 20' will carry either load( according to that chart) but 3600 watts at 12 volts is 300 amps which #6 will not carry for very long...MikeD74T