50 amp circuit for stick welder

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After a lot of searching on CL I finally scored a used Thunderbolt AC/DC with a 30/50 amp plug (looks like your basic dryer plug). When I wired my garage I added several 220 V circuits using 12/2 wire and 30amp breakers. I used a 20Amp plugs cause that's all I could find at the local hardware store. At the time I didn't have any tools that drew more than 20 amps, so I didn't see a problem.This welder can draw 47.5 amps according to the manual so it would trip a 30A circuit if I ran it full power. I doubt I ever will need that much juice but I'm considering upgrading one of my 220V circuits to the higher amperage.Questions is, would I need to run new wire or would the 12/2 be sufficient? If I rewire, I probably would not need to run more than 20' of wire from the box to an outlet.Or, asked another way, if I never weld anything thicker than 1/4" would I need more than 30A?
Reply:I know my old AC stick machine would trip a 30 amp breaker if I ran 1/8" 7018. As long as I stayed with 3/32" rods I was fine. Never tried to run the AC/DC Thunderbolt on 30 amps, so I can only guess that it would be similar..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:12/2 wire is good only for 20 amps.  That's not enough to run this welder for most anything.You need a minimum of 30 amps (#10 AWG wire) but ideally would like 50 amps (#8 AWG wire).Since it looks like you have to run new heavier wire anyway, it seems a 'no brainer' to run the heavier #8 wire and have the full capability of your welder.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:I'd run a 50A circuit. If the circuit is dedicated to the welder (in other words, if you never run anything except your welder on that circuit), you can use AWG10 because welders are not continuous loads (you have to let them cool off every 10 minutes if you run them wide open). This allows you to use a lighter wire than you would need for a circuit that fed a continuous load of the same draw and still be "code."If you wanted to run something on the circuit that drew 50A continuously, you'd need heavier wire.For more info, see NEC article 630.
Reply:50 amp breaker, #6 wire. You could get by with #8 wire but check codes in your town.    Or get a licensed electrician to install it. That way if your shop burns down your insurance company will pay to rebuild it. www.georgesplasmacuttershop.comPlasma Cutter and Welder Sales and Repairs--Ebay storeTec.Mo. Dealer Consumables for the PT and IPT torch's
Reply:Originally Posted by mechanic41650 amp breaker, #6 wire. You could get by with #8 wire but check codes in your town.    Or get a licensed electrician to install it. That way if your shop burns down your insurance company will pay to rebuild it.
Reply:thanks everyone. I looked tonight and I actually used 12/2 for the 125v circuits and 10/2 for the 240 v circuits so at least it's good for 30A. But I guess I'll replace one of the 30s with a 50A and some 6/2 wire ($4/foot!). I'll have to make it a short run! Luckily the Thunderbolt came with nice long cord and 75' leads.
Reply:hi,how many feet do you need ???   Are you using conduit ???  6/2,  $4.00 PER FOOT ?you better get more pricing. Just a quick search showed #6 at about  $1.00 per foot. http://www.zorotools.com/g/00075471/...aign=shopzilla
Reply:You can actually run that machine on 12g and a 50amp Breaker due to the Duty Cycle.Since you have 10g wiring I wouldn't be afraid of putting a 50 amp breaker in there.One man shop- no one else using the place.Unless you are running a Kiln doubt any of your machines will be a problem on that Circuit.http://www.millerwelds.com/om/o316g_mil.pdfCheck out the Electrical service sectionEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Originally Posted by Broccoli1You can actually run that machine on 12g and a 50amp Breaker due to the Duty Cycle.Since you have 10g wiring I wouldn't be afraid of putting a 50 amp breaker in there.
Reply:Originally Posted by ian1386NEC code 240.3 says that 10g is rated up to 30 amps. You'll need 6g, like has been mentioned, to run 50 amps. Sure, you could throw a 50A breaker on a 10g circuit and you might be fine, but your installation would be illegal, dangerous, and good luck claiming insurance if anything were to happen. Please don't suggest these types of things to people...[disclaimer: I'm not an electrician, but am in the process of redoing my garage so I've been looking into all of this stuff lately]That's exactly what you need to do, though you should be able to find 6/2 for much less than $4/ft.  Here's a 20ft length of 6/2 for $40 and free shipping ($2/ft): http://www.ebay.com/itm/6-2-W-GROUND...a#ht_500wt_904
Reply:Ed is absolutely correct. If you're going to quote NEC codes at least quote the proper one! NEC 630. The folks that wrote/govern the NEC realize that welders are an intermittant load machine and they placed Code 630 in the code book to cover usage of lighter gauge wiring for dedicated welder circuits...gotta rmember the dedicated circuit part.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Originally Posted by Broccoli1I understand your concern but it IS allowable and I'll bet a donut MILLER knows the NEC codes and would not put in their MANUAL70amp Breaker on 10g unless it was ok.What you are describing is for a continuous load- a welding machine on a dedicated circuit, which the OP has, can have smaller wire on a larger Circuit Breaker.Do you think the Power cord on the machine is 6g?
Reply:As you said, your not an electrician, but have you even looked into the NEC reference? Both the 10 ga. wiring and the 50 amp breaker are allowable by code....could even go to 70 amp and still meet code. As far as the original poster not specifying a dedicated circuit, unless he has a significant reason not to dedicate this circuit to the welder let him mark it as such and it meets code. Now, why wouldn't an inspector sign off on this circuit if it meets code...which if it is dedicated, it does.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Originally Posted by WyoRoyAs you said, your not an electrician, but have you even looked into the NEC reference? Both the 10 ga. wiring and the 50 amp breaker are allowable by code....could even go to 70 amp and still meet code. As far as the original poster not specifying a dedicated circuit, unless he has a significant reason not to dedicate this circuit to the welder let him mark it as such and it meets code. Now, why wouldn't an inspector sign off on this circuit if it meets code...which if it is dedicated, it does.]
Reply:Both of us can be slightly wrong. I may be wrong about the 70 amp max breaker...looking at it again it appears that a 50 amp would be the max. Everything else is the same. I believe from the first...posted by Kelvin in post #4...that advice to go with a 50 amp breaker and the 10 ga. wire was as a dedicated circuit...so where is the harm there? Now all I would ask is that if you are going to give advice on wiring, sign-offs by inspectors, legality of the installation and insurance company scare tactics ar least get into the ballpark...Last edited by WyoRoy; 03-09-2012 at 03:50 PM.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:I missed Kelvin's post and was originally concerned with Broccoli's vague statement of "throwing a 50amp breaker" in. Regardless of my lack of electrical experience, I would still recommend 6/2 wiring for a 50amp circuit/outlet, especially for a garage. Who knows what might end up plugged into that outlet? I don't speak as an experienced electrician, but I speak as the son of a fire investigator who has seen too many fires started by insufficient wiring.
Reply:Recommend whatever you see fit. For a dedicated arc welder circuit I'm going to stick with the NEC 630.11 and meet code...Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Or use #6awg and be done with it!!Then you can run a long extension cord if you need it later.  Maybe enough to get to the donut store even  And it will be capable of moving enough juice to keep 3 coal fired plants busy (Well, along the Front Range anyways)"Any day above ground is a good day"http://www.farmersamm.com/
Reply:...................Keep America's enginerrs outta the unemployment line"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by ian1386First of all, I wasn't familiar with NEC630, so I've already been proven slightly wrong. I say 'slightly' because there hasn't been mention of a dedicated circuit. If you're going to give advice on wiring, all I ask is that you don't assume these types of things and then give advice which could very well be dangerous if not used how you're assuming.
Reply:Confused  ?  i think regardless what the  breaker served, If its a 50 amp breaker the wire needs to be rated for 50Amps end of story. its when people try to cut corners problems occur. Forget about any  kind of marking.  50 AMP number 6 wire .    I have welded where the stinger cable got HOT on a 50 amp circuit with number 6 power wiring; I can't imagine how hot smaller gauge power wiring could be. Regardless of what could be done ,or what you may be able to get away with, ITS NOT WORTH IT . I wonder what would happen if that panel was opened by a inspector and he saw a 50 amp breaker with number 10 wire. I don't think he would be looking for any kind of marking or tag . That would be like installing a plexiglass panel in a fire extinguisher cabinet that should have glass where it says "BREAK GLASS"
Reply:Jeez Louise, how many times a week do we go through this NEC article 630 business?
Reply:No need to get all in a huff. The NEC lists minimum wire sizes allowable in all these instances. If anyone feels the need to run a 4 aught for a 50 amp welder circuit feel free to do so as long as it is suitable for use in the terminating lugs provided by the equipment it is being attached to. As far as arguing with the NECs minimums, that's a non-argument. A whole hoard of input from a lot of great minds over a period of many many many years has gone into the current NEC."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:thanks...now I'm completely confused. This website: http://www.csgnetwork.com/wiresizecalc.html and this website: http://www.gorhamschaffler.com/wire_...alculator.html both show I only need 10 ga wire for 50 foot total run (25 feet to a DEDICATED welder outlet and 25' cord on the welder). But NEMA seems to think a 50A breaker ALWAYS has to have 6ga wire.I actually think I will take this welder to the wife's shop and leave it there so the question might be moot (get the landlord to install the 50A circuit and it's on him). This welder will never be run at 100% duty cycle, and I doubt I'll ever crank up the juice for anything bigger than 1/4" steel. But unless I'm missing something, it seems like I ought to be able to actually use it lightly in my garage with 10ga wire on a 50A circuit. Please help me understand the conflict between the two website calculators and what you tell me is code.I'm not familiar with NEMA codes, but as the NEC is the National Electrical Code and seems never to err on the side of under valueing their minimum recommendations I'd go with them. Your inspector is going to go with the NEC code unless your municipality, county or state requires a more stringent interpretation.Note your welder's 20% duty cycle on the chart below. In the first column to the right there is a listing for a multiplier of 0.45. As you stated in your first post, your welder requires 47.5 amps at maximum. Multiply 47.5 by 0.45 and you have a 21.375 amp rating on a "dedicated" welding circuit. As 10 ga. wire is good for 30 amps, you are covered per NEC code. The 50 amp breaker is covered in the same section of the code as being less than the maximum of 200% of your wiring's rating and is also to code per the NEC. You should be able to run your welder at it's highest setting, as long as you abide with it's duty cycle, using a 'dedicated' 50 amp breaker/10 ga. wiring circuit. Label the circuit as such. Understand that the circuit is dedicated and not to be used for continuous load operation of motors, heaters, etc.Post a link to the NEMA section you were speaking of. I'd be interested in looking at it.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Roy,The Welder 47.5 amps is @ RATED outputThe manual calls for a 70amp Breaker  if he really wants to run it wide open.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Thanks WyoRoy, this is good info. Even at the maximum output the unit is only rated at a 20% duty cycle as you said. And I doubt I will ever run it at maximum amps.  Broccoli1, the manual specifies a recommended 70amp breaker but it also specifies 12 ga input wirehttps://www.weldingweb.com/images/smilies/confused.gifFor now I'm gonna see how it works with just the existing 30A breaker and 10ga wire. Like I said, I don't have any projects that will require me to set this baby at 11. So if it throws the breaker all the time, I'll upgrade to 50A and 6ga wire.
Reply:See how your welder behaves on that circuit. If you need more amps than that 30 amp breaker allows before kicking just go with a 50 amp...although if a 60 amp breaker is available it will still meet the 200% over amp rating allowed for a dedicated circuit with your 10 ga. wiring. I have been quoting the NEC minimum rating for your 20% duty cycle welder on a 10 ga. circuit, so you shouldn't have to install larger ga. wiring unless you wish to run other equipment off that circuit when you aren't welding.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Ed,Just saw your post about the 70 amp breaker. Its a pain in the tail looking up NEC code on the Internet and my Cheats Guide and copy of the NEC are both down at the shop. I've been going with the 200% maximum over amp breaker rating for a 30 amp dedicated welder circuit from a quick glance off what I could find on the NEC in the 630 section for welders, but it well may have been a higher value...I know it wasn't less than that. I'll have to stop by the shop tonight before work and pick up one or the other to see if it was 200% or 250%.Lincoln PrecisionTig 275Miller 251Miller DialArc 250Bridgeport millHossfeld bender & diesLogan shaperJet 14 X 40 latheSouth Bend 9" 'C'Hypertherm 900Ellis 3000 band saw21"Royersford ExcelsiorTwo shops, still too many tools.
Reply:Originally Posted by mechanic41650 amp breaker, #6 wire. You could get by with #8 wire but check codes in your town.    Or get a licensed electrician to install it. That way if your shop burns down your insurance company will pay to rebuild it.