# 220V Extension Cord for Welding



## erikmannie (May 21, 2022)

I ran out of space in my garage, & now I am moving my welding table outside.

My 220V, 40A outlet needs to stay where it is because it is needed for 3-phase machine tools.

At this welding outlet (I will post a photo), I have an extra 4-prong, single phase female receptacle which is no longer needed.

I want to dedicate that second outlet (which  also has a 40A circuit breaker) for my welding. My welding will occur about 50 feet away from here. My welding machines are all single phase 220V & only go up to 255A.


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## erikmannie (May 21, 2022)

I will TIG inside the garage (distance from outlet is 20 feet), and MIG + stick outside at a distance of 50 feet.

My Dad is a retired electrician, but he has some health challenges which affect his manual dexterity. He will direct me to do the work. We don’t need to work at the panel because I have been using the 40A circuit breaker for years, & it has never tripped.


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## erikmannie (May 21, 2022)

My questions are:

(1) Should I run wire (in a conduit) from the outlet along the garage wall in order to hard wire a welding outlet closer to the welding site? I don’t see what I would gain from this. The wire coming from the panel is either 8 or 10 AWG, and the extension cords that I am looking at are 8 AWG. A conduit along the wall would be ugly, & would move the outlet farther away from the TIG welding area.

(2) Am I okay with a 50 foot, 8 AWG extension cord for my 220V welding up to 255A?


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## erikmannie (May 21, 2022)

As I understand it, the penalty for using an extension cord (or a longer electrode lead, as in stick welding) is the need to turn up the Amps on the machine every time you weld using an extension cord. This will nerf my machines a little; where I could have run a single bead on 1/4”, for example, I may now need to add another pass for that.

I understand that I will pay a little more money for kWh that were lost to heat, but I am prepared to accept this.


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## erikmannie (May 21, 2022)

One wonders what percentage of extra Amps are required for every 25’ of lead.

My machines came with a 6’ cord. I could have tried to make do with a 25’ extension cord, but that would have been too short for some jobs.

With a 50’ extension cord, I can do everything that I want to do.

Hopefully I will be okay to move forward welding up to 255A with an 8 AWG, 50’ extension cord on a 220V, 40A circuit.


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## rabler (May 21, 2022)

8 AWG copper has a resistance of .064 ohms/100ft.  Power lost will be I*I*R, so worst case is 40 amps * 40 amps * .064 = 102 watts per 100ft.  Call it 1 watt per foot.  Additional voltage drop for the extension cord will be about 40A * .064 ohms = 2.56 volts.  You'll get some extra loss due to the additional plug but not much.  Overall I doubt you'll notice the difference.

editted to add: That said, I'd probably look for 6 awg cord since you're probably using a 50A plug.  That way your cord is safer for use on any 40A or 50A circuit.


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## erikmannie (May 21, 2022)

rabler said:


> 8 AWG copper has a resistance of .064 ohms/100ft.  Power lost will be I*I*R, so worst case is 40 amps * 40 amps * .064 = 102 watts per 100ft.  Call it 1 watt per foot.  Voltage drop will be about 40A * .064 ohms = 2.56 volts.  You'll get some extra loss due to the additional plug but not much.  Overall I doubt you'll notice the difference.


So 2.56V per foot, or 128V over 50 feet.

128V sounds like a lot!

I guess the welder adjusts for this by turning up the machine a bit.


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## rabler (May 21, 2022)

erikmannie said:


> So 2.56V per foot, or 128V over 50 feet.
> 
> 128V sounds like a lot!


2.56V total over 100ft.


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## erikmannie (May 21, 2022)

rabler said:


> 2.56V over 100ft.


What a relief! Taking 2.56V from 220V is a loss of only 1.16% electrical potential.


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## erikmannie (May 21, 2022)

Here is the outlet that I am working on today. I am going to change the 4-prong female to a 6-50R (3-prong) female.


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## erikmannie (May 21, 2022)

This is the 6-50R female that I will buy at Home Depot today:


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## Aukai (May 21, 2022)

I have run a 50' extension cord for my MIG welder, and noticed no difference.


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## erikmannie (May 21, 2022)

I ended up buying the extension cord below for $81.10 delivered.

I will have to make do with the 25’ length for financial reasons.

They did not have one in stock at any store around here, so Home Depot is going to ship it to my house for free.









						Southwire 25 ft. 8/3 STW 6-50 Heavy-Duty Welder Power Extension Cord 19178806 - The Home Depot
					

This 25 ft. 8/3 STW 6-50 Welder Extension Cord comes with an 8-Gauge plug and a STW jacket for heavy-duty performance. Lighted receptacle end indicates when power is on. Molded ends offer safety and convenience



					www.homedepot.com


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## Aukai (May 21, 2022)

I got my 50' from Amazon


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## RJSakowski (May 21, 2022)

I used triplex when I needed some extra distance for my welder.    I just added a plug and socket to make up the extension.  It's not very flexible but it doesn't need to be.


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## erikmannie (May 21, 2022)

@RJSakowski 

Like this?









						Triplex Cable, 8 AWG
					

8 AWG triplex boat cable, built from finely stranded tinned copper conductors & designed with a moisture-resistant interior. Built to be flexible, durable, & affordable. It is resistant to acid, alkali, oil, flame, moisture, gasoline, & abrasion. Easy to install & built to last. BUY DIRECT & SAVE!




					www.pacergroup.net


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## RJSakowski (May 21, 2022)

erikmannie said:


> @RJSakowski
> 
> Like this?
> 
> ...


No, the kind for burial or overhead power.  I used what I had laying around from a previous wiring job.


			https://www.prioritywire.com/specs/Triplex%20Service%20Drop.pdf
		

  I believe I used AWG4.


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## Bi11Hudson (May 21, 2022)

There's nothing that I can add, in reality every situation is different. I have a Lincoln 225 buzz box (copper windings) that I converted to DC many years back. Most of my welding is in the 40-60 amp region with 1/8 4011 (I think) rods. Some of it is for my tractor accessories, some for shelf standards, things of that nature. The only thing that needed to be "accurate", I took to work and had a buddy weld. That was before 2005, so my memory has gotten a little fuzzy. . . He made the welds at 60ish amps on an industrial machine. 

The point here is that at 60 amps at the electrode on the Lincoln (transformer type) the line load was well below 30 amps. When I rebuilt the machine, I included a 50 ft cord, replacing the OEM cord. I keep it in the barn and roll it outside to weld, no need for an extension. The OEM specification for 60 amps is around 50%. I am sure I have exceeded that several times. The cable I used was SO 8/3, ~50 feet, and has never gotten warm, well never above ambient. Although the plug is wired for and uses a 50 amp connector, the circuit breaker is a 30 amp 2 pole. I use the same plug for a generator when it's run, so the breaker is set to protect the genset. It has never tripped. . . 

Although I have seen, but *certainly don't agree with*, using NM 10-2+G. Some jack leg wannabe fixers will do whatever is necessary. 

.


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## epanzella (May 21, 2022)

My cord is 6/3. For 50 ft I would go no lighter. You also need to include the length of the line between the outlet you want to use and the main panel. My biggest draw is a  250A Miller AC/DC transformer machine. My MIG & TIG draw much less.


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## Flyinfool (May 22, 2022)

My welder outlet is under 10 feet of wire from the beaker to the outlet.
I have a 200 amp MIG welder, the factory power cord is 10 feet SO 8-2, I permanently lengthened that by adding 15 feet of SO 6-2, I also have a 75 foot extension cord that is 4-2 (I do not remember the type). It is not a type made for extension cord but in use it does not need to be flexible, It is used very seldom, like once every 5+ years, and I roll it into large coils to minimize the actual amount of bending that it sees.


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## samstu (May 22, 2022)

I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators.  Lots of time for cooling occurs in a non-production environment.

You can find this in article 630 of national electrical code.  But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder.   Local codes and your own comfort level may vary.

I suspect most home welder wiring is over-sized.


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## G-ManBart (May 23, 2022)

samstu said:


> I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators.  Lots of time for cooling occurs in a non-production environment.
> 
> You can find this in article 630 of national electrical code.  But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder.   Local codes and your own comfort level may vary.
> 
> I suspect most home welder wiring is over-sized.


That is true, but that's a slightly different topic than what the OP was asking about.  Sizing the conductors and breaker covers the safety aspect...essentially heat as you mention.  The OP was worried there would be too much voltage loss due to the length of the cable.  Most charts start at 50ft, so under that it's rarely a concern.


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## erikmannie (May 23, 2022)

samstu said:


> I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators.  Lots of time for cooling occurs in a non-production environment.
> 
> You can find this in article 630 of national electrical code.  But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder.   Local codes and your own comfort level may vary.
> 
> I suspect most home welder wiring is over-sized.


A great deal of the welding that I do is practicing on coupons, and sometimes with the machine at max current. As such, a large number of coupons are prepped & ready to roll. Under these circumstances, the machine gets quite a workout.

So far, I have never had a machine switch off because I hit the duty cycle limit. I often wonder if, once an operator hits the limit on a duty cycle, the machine is engineered to “auto-shutdown” and cool off.


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## G-ManBart (May 23, 2022)

erikmannie said:


> A great deal of the welding that I do is practicing on coupons, and sometimes with the machine at max current. As such, a large number of coupons are prepped & ready to roll. Under these circumstances, the machine gets quite a workout.
> 
> So far, I have never had a machine switch off because I hit the duty cycle limit. *I often wonder if, once an operator hits the limit on a duty cycle, the machine is engineered to “auto-shutdown” and cool off*.


It really depends on the machine.  Most modern welders will have a thermal protection circuit which shuts off welding current but keeps the machine on with the fan running if it gets too hot.  I'm sure you could get all sorts of arguments on a welding forum over whether that only happens if you exceed the duty cycle a lot or just a little, etc.  In practice, the actual duty cycle will vary with ambient temperature as well, so there's the book duty cycle, the actual duty cycle and when the machine will cut welding output, and the three may not match.

Mr. Tig over on Weld.com did a video on duty cycle with a bunch of smaller/less expensive welders and most of them would exceed their listed duty cycles before thermal cutoff.  It's almost hard to watch!


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## Winegrower (May 23, 2022)

I apologize for the detour, ignore as needed.   A friend brought his freshman high schooler over as he was interested in electricity/electronics.   I took him through voltage, current, resistance, power and energy…he’s very bright, caught on immediately, and could solve problems like “how much horsepower can you get from a 120V 15A circuit”.   I gave him an old HP3478 DVM and he left happy, and I told him he now knows more about electricity than 99% of the people on earth.  

It is always surprising how little most folks really know about the basics, since who really tries to teach this?   I got nothing in high school and college level courses can leave you with memorized Maxwell’s equations, but good luck doing anything with that.

Ah, I must be getting old.


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