Electrical service for welder

1944bgardner · Apr 23, 2012

I have a Hobart Stickmate LX AC/DC welder and need to run electrical service out to my barn. The welder manual recommends min 12 AWG with max length 87'. I have a 200 amp panel in the house with room to add this circuit. Plan to add 50 amp breaker with a run of @ 50'. 12 AWG with 87' run seems alittle weak to me. What would you guys recommend? I'm gonna get a more accurate measurement of the length and go from there. Thanks Jim

dr sportster · Apr 23, 2012

You can't protect 12 awg on a fifty amp breaker. Not much VD at 50 ft. You will need bigger wire or smaller breaker.

Bob Bancroft · Apr 23, 2012

WHAT?
I'm no electrician, but we use #10 on a 30 amp circuit. Shoot, on a 50, I think it was #6.

retired farmer · Apr 23, 2012

I think mine was at least four or six guage in my shop. I sure wouldn't use 12 guage. That is for house lights.

John T · Apr 23, 2012

YOU CANT PROPERLY PROTECT WIRE RATED FOR 20 AMPS USING A 50 AMP BREAKER, IT WOULD REQUIRE ONLY A 20 AMP BREAKER.

IF YOU USE A 50 AMP BREAKER, THEN THE WIRES AMPACITY NEEDS TO BE 50 AMPS ALSO (or if 20 amp wire then 20 amp breaker)

Heres the method I used wayyyyyyyyy back when I was an elctrical power distribution design enginner but Im rusty as an old nail so NO WARRANTY, consult a local qualified competent electrician or engineer AND YOUR LOCAL AUTHORITY (if any such exists) as its what THEY say NOT anyone here that matters

1) First of all you size the load

2) Then you size the wire so the maximum continuous load isnt over 80% of the wires ampacity AND OVERSIZE AS/IF NEEDED DUE TO EXCESS LONG RUN VOLTAGE DROP

3) THEN FINALLY you size the overcurrent protection device (breaker or fuze) to match and protect the wires ampacity

I.E. 50 AMP BREAKER FOR 50 AMP WIRE OR 20 AMP FOR 20 AMP RATED WIRE

NOW YOU ASK FOR RECOMMENDATIONS: Again consult LOCAL AUTHORITY not Billy Bob or the know it all brother in law or lay persons or any of us here (CERTAINLY including yours truly) and consult trained competent qualified PROFESSIONALS instead of non trained lay persons....

That being said, if I (NOT expert was trained professional but too long retired now, ask/trust the current practicing electricians and engineers here over me) were providing power to a remote barn I would at the minimum provide:

1) At least, 50 amps, better yet 100 amps, of 120/240 Volt Single Phase Three Wire service

2) With Three conductor PLUS Equipment Ground (4 total) wire (2 Hots, 1 Neutral, 1 Equipment Ground) that could be direct in trench buried like Underground Feeded (UF) or Underground Service Entrance (USE I believe) or run individual THWN conductors inside buried conduit MAYBE PLASTIC EXCEPT IF UNDER DRIVEWAY USE RIGID or concrete encasement etc CONSULY LOCAL AUTHORITY.

3) Again size the breaker for the wires ampacity (50 or 100 amp etc) and oversize the wire as/if needed to reduce voltage drop to acceptable levels. i.e. might need 60 or 120 amp wire versus 50 or 100 USE VOLTAGE DROP CHARTS

4) At the barn you MUST USE a sub panel (like 50 or 100 amp whichever you so choose) that has the capacity for seperated and isolated Neutral Busses and equipment Ground Busses

5) FOR THE 100TH TIME AT THE BARN DO NOTTTTTTTTTTT BOND NEUTRAL BUSS TO GROUND BUSS they are to be kept seperated and isolated.

6) Establish a Grounding Electrode (made such as driven rod or rods and/or conductive buried utility pipes and/or structural steel etc etc CONSULT LOCAL AUTHORITY) AS BUILDING ELECTRICAL SERVICES REQUIRE SUCH and bond it to the grounding Electrode conductor (like No 4 bare copper) which leads to the panel.

SUMAMRY Id run at least 50 amp or better 100 amps of 120/240 single phase three wires of electrical service to a remote outbuilding nottttttttttttttttt just 20 and size the wire and breaker per the above and LOCAL AUTHORITY

I did this in a hurry so if I missed anything hopefully the other fine knowledgeable and ezperienced and MORE CURRENT electricians and engineers here can add to and/or correct this, I apologize.......

John T

David G · Apr 23, 2012

You need at LEAST #6.

You will probably start a fire otherwise.

paul · Apr 23, 2012

Their thinking is a 20% use rate, so the wire has time to cool down. Because the welder should be on only 20% of the time, becsause it too is wired to flimsy - the way things are made these days.

However, once you have your wiring out to the shed, you will be using it for other things - if even just lights, so clearly you need to run a bigger proper wire out there as the others suggest.

--->Paul

1944bgardner · Apr 23, 2012

I have power to the barn fed from a 30 amp breaker from the house. It's run thru #10, the barn has 2 circuits, one 15 amp and one 25 amp. Thanks to all for the advice Jim

buickanddeere · Apr 23, 2012

That sounds like the Mexican electrical code rules.
Time to run a conduit out to the shed and pull in three insulated #2 copper and a bare #6 copper. Drive two ten foot ground rods at the shed. Open the ground to neutral bond in the shed panel.
Is there currently any other source of power to the shed for lights etc?

RodinNS · Apr 23, 2012

I think if I was doing this again I would use a #4 for that distance. I've got one on a 50 amp breaker and #8 wire. It does OK.... but I'd wager that there's more voltage drop there under load than is acceptable given the draw that's on it.

Rod

Mike (WA) · Apr 23, 2012

Be interesting to see what the local authorities come up with for wire size. Unless you don't plan to get them involved.

Knowing B&D tends to err on the side of caution, I'm thinking it'll come in at about #6.

buickanddeere · Apr 23, 2012

I was thinking a whole 100amp service in the shed for lights,welder, future air compressor etc.
I suspect the shed lights are currently operated from an extension cord ran across the lawn.
If running a conduit and wires for "just" a welder plug. One would be daft not to actually install a service instead.

John T · Apr 23, 2012

6 will most likely suffice depending on the load, distance and voltage drop allowances, but anytime its anywhere near close to the NEC limits (minumum standards) I ALWAYS UPGRADED ANYWAY thats just how I was taught and how Im "wired" personally.

He will still use a 50 amp breaker for 50 amp rated wire, of course, its just that he may need to bump it up for voltage drop or if the max continuous load is greater then 80% of the wires ampacity. How I did it anyway???????

Fun chat for sparkies at least, though boring to others Im sure

PS were gonna be RVing in San Diego (Son is there) this summer but notttttttttt all the way up North in your country. Crater Lake is still the most beautiful lake Ive ever seen

John T

paul · Apr 23, 2012

Now, back in 1970's we had an electric feed to the breaker on a building, and an electric feed to a deep well, breaker box was in the same building.

When I rewired in 2008 they got all excited, not allowed to have two different feeds to the same building, had to clean that up and have one drop to the building, feeding the main breaker, and then on to the deep well and the rest of the circuts from the single main on the building.

So, if you already have a feed to this building, are you planning to run a second feed, and is this allowed, or are you starting over with a nice big main feed to the building?

--->Paul

paul · Apr 23, 2012

Sounds like there is already a 30 amp service, I hope he's not planning on running a second sevice to the building just for the welder - don't think that to code?

Anyhow, it gets real messy that way, better to just do it right and run a bigger service to the shed, and branch from tht box to the welder, lights, etc. As things should be.

It sure was expensive re-wiring the farm in 2008, they put 200 amp wire and 4 outdoor splice boces throught the farmstead. Two years ago when I put up the new machine shed it sure was easy & cheaper to branch off and bring full power up to that shed, didn't have to route around existing wires, and back to the main transformer far away.

Wiring will get you sooner or later, might as well do it right the first time, you'll just be re-doing it the next time and throwing away the 1st effort as totally wasted.

--->Paul

JRSutton · Apr 23, 2012

Man - that might work ok for THAT welder if everything operates properly... but when they say minimum, I'd say they certainly MEAN minimum.

Aside from the obvious safety concerns, you'd be much better off wiring now for anything that you may use on that line in the future (like a bigger welder).

Do it right the first time. Copper's not cheap, but neither is a new barn/house.

buickanddeere · Apr 23, 2012

(quoted from post at 10:51:09 04/23/12) YOU CANT PROPERLY PROTECT WIRE RATED FOR 20 AMPS USING A 50 AMP BREAKER, IT WOULD REQUIRE ONLY A 20 AMP BREAKER.

IF YOU USE A 50 AMP BREAKER, THEN THE WIRES AMPACITY NEEDS TO BE 50 AMPS ALSO (or if 20 amp wire then 20 amp breaker)

Heres the method I used wayyyyyyyyy back when I was an elctrical power distribution design enginner but Im rusty as an old nail so NO WARRANTY, consult a local qualified competent electrician or engineer AND YOUR LOCAL AUTHORITY (if any such exists) as its what THEY say NOT anyone here that matters

1) First of all you size the load

2) Then you size the wire so the maximum continuous load isnt over 80% of the wires ampacity AND OVERSIZE AS/IF NEEDED DUE TO EXCESS LONG RUN VOLTAGE DROP

3) THEN FINALLY you size the overcurrent protection device (breaker or fuze) to match and protect the wires ampacity

I.E. 50 AMP BREAKER FOR 50 AMP WIRE OR 20 AMP FOR 20 AMP RATED WIRE

NOW YOU ASK FOR RECOMMENDATIONS: Again consult LOCAL AUTHORITY not Billy Bob or the know it all brother in law or lay persons or any of us here (CERTAINLY including yours truly) and consult trained competent qualified PROFESSIONALS instead of non trained lay persons....

That being said, if I (NOT expert was trained professional but too long retired now, ask/trust the current practicing electricians and engineers here over me) were providing power to a remote barn I would at the minimum provide:

1) At least, 50 amps, better yet 100 amps, of 120/240 Volt Single Phase Three Wire service

2) With Three conductor PLUS Equipment Ground (4 total) wire (2 Hots, 1 Neutral, 1 Equipment Ground) that could be direct in trench buried like Underground Feeded (UF) or Underground Service Entrance (USE I believe) or run individual THWN conductors inside buried conduit MAYBE PLASTIC EXCEPT IF UNDER DRIVEWAY USE RIGID or concrete encasement etc CONSULY LOCAL AUTHORITY.

3) Again size the breaker for the wires ampacity (50 or 100 amp etc) and oversize the wire as/if needed to reduce voltage drop to acceptable levels. i.e. might need 60 or 120 amp wire versus 50 or 100 USE VOLTAGE DROP CHARTS

4) At the barn you MUST USE a sub panel (like 50 or 100 amp whichever you so choose) that has the capacity for seperated and isolated Neutral Busses and equipment Ground Busses

5) FOR THE 100TH TIME AT THE BARN DO NOTTTTTTTTTTT BOND NEUTRAL BUSS TO GROUND BUSS they are to be kept seperated and isolated.

6) Establish a Grounding Electrode (made such as driven rod or rods and/or conductive buried utility pipes and/or structural steel etc etc CONSULT LOCAL AUTHORITY) AS BUILDING ELECTRICAL SERVICES REQUIRE SUCH and bond it to the grounding Electrode conductor (like No 4 bare copper) which leads to the panel.

SUMAMRY Id run at least 50 amp or better 100 amps of 120/240 single phase three wires of electrical service to a remote outbuilding nottttttttttttttttt just 20 and size the wire and breaker per the above and LOCAL AUTHORITY

I did this in a hurry so if I missed anything hopefully the other fine knowledgeable and ezperienced and MORE CURRENT electricians and engineers here can add to and/or correct this, I apologize.......

John T

I was just looking in the code book and in one of those "yes, but" situations.
A 12# conductor can be used with 45 amp P rated fuse, 30amp time delay fuse or a 30 amp breaker. IF supplying a motor drawing up to 15 amps and equipped with a 18.75 amp thermal overload.

Charles (in GA) · Apr 23, 2012

"I have power to the barn fed from a 30 amp breaker from the house. It's run thru #10, the barn has 2 circuits, one 15 amp and one 25 amp. Thanks to all for the advice Jim"

So, you already have electrical service to the barn?

For reasons of safety, Electrical Code does not allow two different services or feeds to a building. Its one or the other. If the 30 amp/10 gauge you have, is not sufficient, I'd run an entirely new feed, at least #6 copper, and 60 amp breaker, preferably 2-2-2-4 aluminum quadplex direct burial (aka mobile home feeder) and breaker it at 90 amps. Install a decent panel in the barn.

Charles

Bus Driver · Apr 24, 2012

The NEC has different rules for electric welders. Welders often have duty cycles that limit how many minutes out of an hour they can operate and the supply conductors thus have opportunity to cool. Article 630. If the welder is UL Listed, follow the manufacturers instructions for minimal installation. For the application you list, #8 copper or #6 aluminum will work quite well and be well above the minimum.

David G · Apr 24, 2012

Correct, multiple feeds is a no no

36 Coupe · Apr 25, 2012

I dont agree with #12 wire feeding welders.Duty cycle is ignored a lot.My planer draws 26 amps so it would have a bad voltge drop on 12 wire.My Barn is fed by a long run of # 8 wire.I weld out in the yard with a 40 foot # 8 extention cord.I like to see some voltage drop measurements on 87 feet on # 12 wire with a welder drawing 50 amps.The new welders are rigged with # 12 power cords.The Lincoln 225 welder I bought in 1965 has a # 8 crowfoot range cord on it.I note than the welding cables are 1 size smaller on the new ones.
I would never put aluminum wire under ground.Ive seen many failures with underground aluminum wire.

John T · Apr 25, 2012

Of course, the issue isnt necessarily "12 gauge" wire, which may or may not be okay, it, of course, depends on the actual maximum continuous load plus any additional duty cycle considerations peculiar to welding applications... When I designed I obtained the maxumum continuous load and then sized the wire so that current was less then 80% of the wires ampacity. That means if I used say 12 gauge wire with an ampacity of 20 amps my max continuous load had to be no more then 16 amps. Once that was compiuted I then calculated voltage drop based on the wire gauge and load and wire length and if the drop was too great I increased the wire size as necessary

I kinda miss that work lol but too glad to be enjoying retirement

best wishes, fun chat

John T

dr sportster · Apr 25, 2012

I went to an online voltage drop calculator and plugged in the numbers. The first one spit it back out saying that run @ 208 volts would be 100% voltage drop. The second site I went to the calculator automatically[for a single phase 50 amp load at 87 feet ] ---corrected the wire size without doing the VD calculation. The wire size correction went to 6 for a 1.85 % drop [allowable by NEC as acceptable voltage drop]. So even a copmuter ain't runnin' 12 gauge on this run. Won't even do the ridiculus calculation because it's so far off. This was assuming a 208 volt system for 220 even less drop. So 6 AWG is what it is calling for.

36 Coupe · Apr 27, 2012

I would like to see a test run on a welder pulling 50 amps on 87 feet of #12 wire.The voltage drop would be very high.I had my old Weld Master welder doing a few small jobs.The Weld Master has a high and low voltage tap.18 and 25 arc volts.I was having trouble with 7014 because the cable was on the 18v tap.Move to 25v problem gone.Lincoln and Miller are using #12 wire on welder cords.My Lincoln 225 I bought in 1965 has a crow foot range cord with # 8 wire.

Electrical service for welder

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