Help Please with Wire / breaker for Arc Welder

[Tim Fitzgerald]

I have read several threads and see that there are several possibilities. I am wanting to run a dedicated circuit for routine sized arc welder (lincoln sized one sold at Lowes). I may have to run the conductors up to 50 foot to get it ideally where I want it.

What size wire would I need for this. I have read everything from 6-10 and breakers 30-50 A. I am assuming the wire would be the Romex type and that I will only need 2wire with ground...?

 

[BD1]

Where and to are you running wires ? Underground ? House to building ? OR
from a panel in garage to a location in garage ? Conduit or Romex per code ? Are you gonna feed a new panel and run from new panel to outlet ?
Need a little more info.
I ran mine in conduit 60 feet with three #6's from panel to outlet with a 50 amp breaker for a dedicated welding outlet. Cheaper running larger wire the first time.

 

[Stuart in MN]

Also, please mention where you're located - the rules may be different depending on what state or country you live in.

 

[Tim Fitzgerald]

I live in Louisiana. Wire will be THHN, ran in conduit (size of conduit I need advice on as well). I dont know if 50 amp breaker is overkill and have read various sizes of wire to use. The welder will not be used on a daily basis and will be a nice to have thing. I dont want to go back and do this again...

Alsois there and code rule about running a larger amp breaker below a smaller one. Say for instance I have three 20's in my new panel, do the largest breakers have to be on top...? just want to be sure before I end up having to change all of that as my 50 amyp breaker (if needed for welder) will most likely be near middle of panel

 

[DeadSock]

For a Lincoln "tombstone" welder, make it 50a. A 30a circuit would likely suffice if you never plan to burn more than 3/8", but the price difference isn't much I would guess.

You might also consider running a neutral and putting a 14-50 outlet in. It's an additional conductor (I think can be downsized?), but allows for future uses (e.g. RV, subpanel, elec. car, etc).

 

[sberry]

Pipe is the best, as is a single circuit in the pipe. Use a 3/4 and run 3 number 10 on a 50A breaker. This is actually one wire size above the minimum code at 50 ft for any welder sold in Lowes.

 

[DeadSock]

sberry,
is the AWG 10 because it's a welder?
What if that 50' was used for something else later (e.g continuos load)?

 

[sberry]

Yes, its not for an oven or a kiln. The welding machines at a Lowes all come with a 12 cord.

 

[Bruce4310TX]

Pipe is the best, as is a single circuit in the pipe. Use a 3/4 and run 3 number 10 on a 50A breaker. This is actually one wire size above the minimum code at 50 ft for any welder sold in Lowes.

are you able to use #10 because its a intermittent load ? i was thinking i should use #8, i have 2 spools of #10 was wondering if i should sell it and go bigger would be great to use it instead.

 

[BD1]

Pipe is the best, as is a single circuit in the pipe. Use a 3/4 and run 3 number 10 on a 50A breaker. This is actually one wire size above the minimum code at 50 ft for any welder sold in Lowes.

Ah, 10 gauge wire is good for 30 amps. That means a 30 AMP BREAKER. If you run 10 gauge wire and use a 50 amp breaker, the wire will overheat and the 50 amp breaker will be like new.
The breaker is to protect the wire. If you want a 50 amp breaker I think code is 6 gauge wire. If using THNN one chart states #8 is ok. Check your local code.
http://groverelectric.com/howto/08_How to Calculate Breaker Wire Size & Wattage.pdf

http://www.generation3electric.com/wire_size_chart.php

 

[Bjm364]

You have to match your supply to the load. Check on the nameplate on the machine. It should tell you voltage and amps or FLA(full load amps). If the amp draw is less than 30 amps #10 copper will be fine on a 30 amp breaker. Less than 20, #12 on a 20 amp breaker, etc. For 50 amps you will need #8 copper or upsize to #6 aluminum. Does not matter where the breaker sits in the panel.

 

[sberry]

In this case the primary function of the breaker is for short circuit interruption/ It is code legal to use a 12 on a 50A breaker for a AC225 welder. In this case the primary method to protect the wire is the applied load. The machine has a 12 cord, it wont burn up a 10 wire.

Similar for some motor circuits, breakers much larger than the wire for general circuits, the breaker to protect against a fault and the thermal overload on the motor will open before it overheats the incoming wire, the breaker does almost nothing to protect it from overheat.

 

[BD1]

It doesn't make sense to me to run 10 because THAT machine only has 12 gauge cord. What if you upgrade to a larger machine ? Now you wasted money on 10 to save a few bucks. To me 50 amps is # 6 or 8. I wonder what a inspector would say looking inside a panel that has 50 amp breaker with 10 gauge wire.
Where is it code legal to run 10 gauge for a 50 amp breaker ? I don't know if a electrical inspector will go for the AC 225 welder only idea. Might get away with it if direct wired and no plugs.

 

[sberry]

I wonder what a inspector would say looking inside a panel that has 50 amp breaker with 10 gauge wire.
Where is it code legal to run 10 gauge for a 50 amp breaker ? I don't know if a electrical inspector will go for the AC 225 welder only idea. Might get away with it if direct wired and no plugs.

Where did you learn this?

 

[sberry]

This is different than a machine that does not come with a factory cord. Look at all the 16 wire in the world on a 20A breaker, almost every purchased fixture in your house is like this, 16 ga wire to sockets. The potential load is limited by the fact its connected to an Edison base which limits the size of the lamp that can be screwed in to it.

As for inspectors, this is done all the time. Millions of these were connected when the small electric welder came out in garages all over the country, a piece of 10 cable to the 50A "range" fuses in 60A service panels.
A 200A synchro can be wired with 8 and breaker to 100,,, which is the legal limit for an 8. I believe 12 is the legal limit for a 50.

 

[JoeFin]

Similar for some motor circuits, breakers much larger than the wire for general circuits, the breaker to protect against a fault and the thermal overload on the motor will open before it overheats the incoming wire, the breaker does almost nothing to protect it from overheat.

A Welder is NOT a Motor - and yes you might have trouble convincing an inspector to accept provisions of Article 430 to a welder

Typically a commercial / industrial application welding receptacle will be 50 amps supplied by #6 awg wire on a 50 amp breaker.

Wiring devices rated BELOW 100 amps are only required to have a temp rating 65 deg C. Therefore you'll need to use the 60 deg C column for the ampacity tables.

As for the 12 awg wire appliance cords commonly supplied by the manufacture - that is approved ONLY under the Underwriting Authority and only after the manufacture can sufficiently document the resultant resistance incurred by the appliance cord won't exceed the ability of the overall circuit protection devices to protect the wiring

 

[wyliesdiesels]

I havent seen one person mention this. Ugg!

The code for the size of wiring and circuits for welders is based on the duty cycle of the welder. And when u guys mention and throw around wire size u need to also say what type of wire u are referring to because each type of wire in the same gauge has a different ampacity!!

While yes, building wire feeding a welder can be undersized, the outlet MUST be marked for welder use ONLY! Otherwise, the wire CAN overheat if used for other machines!

If u want to use other machines on the same outlet as the welder, u cant if the coductors are reduced and then it would be a waste of money to size the circuit based on a welder!

So OP, what is the duty cycle of the welder?

A Welder is NOT a Motor - and yes you might have trouble convincing an inspector to accept provisions of Article 430 to a welder

Typically a commercial / industrial application welding receptacle will be 50 amps supplied by #6 awg wire on a 50 amp breaker.

Wiring devices rated BELOW 100 amps are only required to have a temp rating 65 deg C. Therefore you'll need to use the 60 deg C column for the ampacity tables.

As for the 12 awg wire appliance cords commonly supplied by the manufacture - that is approved ONLY under the Underwriting Authority and only after the manufacture can sufficiently document the resultant resistance incurred by the appliance cord won't exceed the ability of the overall circuit protection devices to protect the wiring

This code only applies to devices and wire that doesnt have a temperature rating or the rating is unknown. If he uses THHN, then he should be able to size the circuit based on the 75* C ampacity!

 

[JoeFin]

This code only applies to devices and wire that doesnt have a temperature rating or the rating is unknown. If he uses THHN, then he should be able to size the circuit based on the 75* C ampacity!

Nope - those temperature ratings come from the Underwriters laboratories and the NEC adopted them into the code in 1996

So unless they are rated for a HIGHER Temperature rating (as not marked with a temp rating) then you have to use the values given - 100 amps and above 75 C deg - Below 100 amps 65 C deg

Check article 110 -14 sub c

Read your code book - it does an electrician good

If the Welder has a Duty Cycle - THEN can you derate by the table in 630 -31. IF the Duty Cycle is not listed on the name plate - then No

50% duty then x 0.71 ... on down to 5% Duty @ 0.22

 

[madosta]

All these guys touting who's got the smallest wire with the biggest breaker sure doesn't help you.

Since you're running conduit, use 3/4" and pull two #8 THHN CUs and a #10ground and put it on a 50amp breaker.

If you pulled #10 THHN I would personally protect it with a 30amp breaker - as most welders won't pull more than that, but since it's an arc buzzbox probably, you're best bet is the #8s at a minimum and a 50amp breaker.

 

[sberry]

Look in the owners manual for a 225 buzzer or a Hobart Stickmate. Failure to follow these electrical service guide recommendations could create an electric shock or fire hazard. These recommendations
are for a dedicated branch circuit sized for the rated output and duty cycle of the welding power source.
50/60 Hz
Single
Phase
Input Voltage (V) 230
Input Amperes (A) At Rated Output 47.5
Max Recommended Standard Fuse Rating In Amperes 1
Time-Delay Fuses 2 50
Normal Operating Fuses 3 70
Min Input Conductor Size In AWG 4 12
Max Recommended Input Conductor Length In Feet (Meters) 87 (26)
Min Grounding Conductor Size In AWG 4 12
Reference: 2008 National Electrical Code (NEC) (including article 630)
1 If a circuit breaker is used in place of a fuse, choose a circuit breaker with time-current curves comparable to the recommended fuse.
2 “Time-Delay” fuses are UL class “RK5” . See UL 248.
3 “Normal Operating” (general purpose - no intentional delay) fuses are UL class “K5” (up to and including 60 amps), and UL class “H” ( 65 amps and
above).
4 Conductor data in this section specifies conductor size (excluding flexible cord or cable) between the panelboard and the equipment per NEC Table
310.16. If a flexible cord or cable is used, minimum conductor size may increase. See NEC Table 400.5(A) for flexible cord and cable requirements.

 

[sberry]

http://www.hobartwelders.com/om/0900/o950c_hob.pdf

 

[BD1]

If you were to get a MILLER CST 280 INVERTER machine here's the manual. Page 18 is the electrical requirements.

http://www.millerwelds.com/om/o217655e_mil.pdf

 

[Zeke]

Yes, its not for an oven or a kiln. The welding machines at a Lowes all come with a 12 cord.

It blew my mind when I was welding with another fellow's Miller 140 that was factory wired with 14ga. But, he wanted me to weld with the thing on a 50' 14ga cord and I pulled out a 25' 12ga while telling him no thanks.

 

[JoeFin]

Look in the owners manual for a 225 buzzer or a Hobart Stickmate. Failure to follow these electrical service guide recommendations could create an electric shock or fire hazard. These recommendations
are for a dedicated branch circuit sized for the rated output and duty cycle of the welding power source.
50/60 Hz
Single
Phase
Input Voltage (V) 230
Input Amperes (A) At Rated Output 47.5
Max Recommended Standard Fuse Rating In Amperes 1
Time-Delay Fuses 2 50
Normal Operating Fuses 3 70
Min Input Conductor Size In AWG 4 12
Max Recommended Input Conductor Length In Feet (Meters) 87 (26)
Min Grounding Conductor Size In AWG 4 12
Reference: 2008 National Electrical Code (NEC) (including article 630)
1 If a circuit breaker is used in place of a fuse, choose a circuit breaker with time-current curves comparable to the recommended fuse.
2 “Time-Delay” fuses are UL class “RK5” . See UL 248.
3 “Normal Operating” (general purpose - no intentional delay) fuses are UL class “K5” (up to and including 60 amps), and UL class “H” ( 65 amps and
above).
4 Conductor data in this section specifies conductor size (excluding flexible cord or cable) between the panelboard and the equipment per NEC Table
310.16. If a flexible cord or cable is used, minimum conductor size may increase. See NEC Table 400.5(A) for flexible cord and cable requirements.

Will I owe you an apology

Now as I tried to explain before the manufacture uses a calculated circuit resentence.

So lets start out examining the manufacutre's specs.

47.5 full load amps

Now times that by the rated 20% Duty cycle and table 630-31 (a) (2) gives you a derating factor of .45

47.5 x .45 = 21.5 amps

Which falls in to 25 amps for #12 awg wire (table 310-16) Ampacity of NM, NMC, and MNS Cable (aka Romex) shall be that of 60 Deg C and shall comply with article 310-15 (see article 336-26)

from article 310-15(b)(7) Engineering Supervision
Under Engineering Supervision conductor ampacities shall be permitted to be calculated by means of the following formula

......................... TC - (TA - DeltaTD)
I = Square Root of -----------------------
......................... RDC(1 + YC)RCA


That is what I was trying to explain in the previous post by saying "A Calculated Resentence Formula" when we were discussing the "Derated" appliance cords shipped with the welding units

Now look in the Hobart Specs you listed

Max Recommended Input Conductor Length - 87 ft

You have to count the appliance whip and because every circuit returns to the panel one way or the other the Romex THHN conductor to the welder and back to the panel

6ft Whip = 12 conductor length. Remaining 75' leaves 37.5' of Romex length.

That distance works fine if you mount your welding receptacles next to your panel or you use a fused disconnect on the wall - But you'll have to feed that disconnect with 50 amp wire as NOT to exceed the Maximum allowable resistance for that calculation to work

 

[madosta]

It blew my mind when I was welding with another fellow's Miller 140 that was factory wired with 14ga. But, he wanted me to weld with the thing on a 50' 14ga cord and I pulled out a 25' 12ga while telling him no thanks.

Isn't it nuts? I want a new inverter TIG, but damn... $$$$!!!

 

[sberry]

Not many think the absolute minimum standards are a great idea in most cases,,, a 280 is a unique machine and doesn't come with a fac pak cord. I woudnt wire an outlet for a buzzer with 12 either even if it was close, there is no real reason to. But not having a wire bigger than a 10 wouldn't stop me, my neighbor a licensed master has 15 ft of used 10 cable on an outlet that's been there for 30 yrs.
I bet I have used 20 of those and some nearly melt the machine to a puddle and never overheated the incoming wire, never seen a fire from an under wired welder. Never heard of one personally, I am sure somewhere sometime its been done,,, just never seen it.

Saw some guys with 75 ft of 12 cord on one, not sure how well it worked but the place is still standing.

 

[sberry]

I don't think you need to count each way, it lists 87 ft and this is a 240 circuit. No one is telling anyone to use a wire that wont serve the load either, as I can say again, not many think the 12 is a great idea even if legal but there is certainly a good amount of mis understanding about the NATURE if these circuits and they usually have some kind of reference to "code" which I suspect was a quote overheard from the handyman that "you cant" etc.

The code book is not a good diy study guide, it wasn't meant to be. It leaves out stuff for the layman such as,,,, use a cord bigger than the one the appliance comes with. This is not meant as a method to size conductors for building circuits but its hard to starve the tool or start a fire following that logic when going from outlet to plug.

 

[sberry]

I havnt ran many small 120V feeders and not many from sub standard wire. I have seen it done in body shops. Dipstick has a 100watt lamp burning in a trouble light welder plugged in to it on 25 ft of 16 cord. Have seen this more than once and them blaming the machine. Could have reached an outlet 10 ft away but on a rickety old cord reel. I suspect in the manual it allows up to 50 ft of 14 for a 140. Its second nature anymore to take in to account other factors, some of it becomes instinct. How long am I using it, How hot does it need to be? Am I making one cut or 100, per minute per hour etc. How much work is it to get a better cord?

In the above case with a small machine there could be benefit in trading 25 ft of 12 for 50x14 especially on thicker steel where the machine was set wide open, if the circuit was alreadly long the insult to injury doesn't help.

If I am settling in to a work area or doing something critical beyond the capacity of the equipment then I feel different about all the loss in a cord or hose.

I got a Maxstar. 2 times I popped breakers both in barns at 200 ft on 120V I could turn the machine up to around 75 and stopped in less than a full rod it would hold. I got no idea what the voltage actually was etc. The one place was a customer and it worked, the other was a club and we improved some things where our welder recept was being used for a comp and I stole an un used equipment circuit and got 240/20A, added 100 ft of my own 10 cord and it works great and can use it at capacity.

 

[JoeFin]

I don't think you need to count each way, it lists 87 ft and this is a 240 circuit.

The equation depends on the total resistance and to count that you do in fact need to count the total path to ground (aka: both directions)

The code book is not a good diy study guide, it wasn't meant to be. It leaves out stuff for the layman such as,,,, use a cord bigger than the one the appliance comes with.

Well yes I agree with you on that. Only through a thorough understanding of Electrical Theory does it begin to make sense and once you start to apply those principles combined with some measurements does it all add up and the math hold "True"

This is not meant as a method to size conductors for building circuits but its hard to starve the tool or start a fire following that logic when going from outlet to plug.

This I'll disagree with you on - can't remember the number of installations I was called in on - and you have to remember these are National Accounts for the firm I was working for at the time. So the customer only paid the cost to fly me in, only after the contracted Electricians had given it a try. A second electrical contracting firm, (usually a union shop) had also examined it and drew a blank. And almost inevitably each and every time there was some sort of violation of the NEC at fault for the problem.

I know - I wrote the reports, cited the articles at fault fully demonstrated with the measurements found and the applicable math. That is why I appear to be such a "Bible Thumper" for the NEC. But it has served me very well to document and correct problems.

My biggest concern for the welder at question would be what are the effects of heating from the increased resistance of the smaller wire gage going to be on the internal windings of the transformer (old school welders) or SCRs of the more modern "Inverter" type welders going to be over time ?

 

[sberry]

My biggest concern for the welder at question would be what are the effects of heating from the increased resistance of the smaller wire gage going to be on the internal windings of the transformer (old school welders) or SCRs of the more modern "Inverter" type welders going to be over time ?

Where in the real world did you come up with the math that any or most of this means a pinch of ****? Joe hobby plugs in and uses a machine 5 minutes, with a wire in spec on a machine he cant wear out in his lifetime,,, wear the gun liner out in a lifetime of DIY, will have replaced 5 TV's and several cars before it would be remotely humanly perceptible only on the longest of underpowered circuits if he did run it 24/7

Couldn't save 50 cents a year in wattage lost, not a nickel in a day no matter how much you fussed over it? Too busy running exact numbers to know if it makes a little difference or a lot of difference.

 

[sberry]

Putting a 6 wire in a wall just in case of a bigger machine is about useless. As soon as it would be tailored to the specific machine would lose the general purpose 50A.

Now having said that I have several 6 wire circuits but the cost was low. In reality don't run anything on them where I would notice a difference in wire size, most of them remain un used and when I do connect a portable to one its a 175 feeder.

Here is a thought, the wire4 to a buzzer can be a 12 with a 50 on it,,, at 70A it can run continuous.

 

[sberry]

A new 10 wire to a new recept stapled to the studs and out of harms way is a good thing. About 10x better than some cobbled adapter to a 30A dryer outlet ever was. Can safely leave a machine plugged in to this, not always fukkin with some cobbled scheme. With a switch off a welder is safe. In a machine shop where there was a chance of plugging in a wire feeder at rated output would likely be 8 in pipe, anything better might be used but if I had to buy wire that would be it.

 

[sberry]

All the stuff was made rated at 230,, mine is 243. The machine worked on 50 yr old 60A service, I don't even remember what the incoming g was but pitiful and old and overloaded and corroded but the welder worked. New hotter juice and its perfect and can turn it down 5A on the dial with a 1/8 6011. Somehow we lost about 3A output give or take a pinch and had to use the next setting. Burn a whole handful of 1/8 lo hi on one at a time.

Even building a log splitter a hobby type couldn't run it that hard, lining a dump box etc. I burned a 1000 pounds of rods on one connected to a power pole with a 10 Romex. My money is the thing still works today.

 

[JoeFin]

Now having said that I have several 6 wire circuits but the cost was low. In reality don't run anything on them where I would notice a difference in wire size, most of them remain un used and when I do connect a portable to one its a 175 feeder.

Here is a thought, the wire4 to a buzzer can be a 12 with a 50 on it,,, at 70A it can run continuous.

That's what I believe the manufacture's notes were really trying to explain. You can put up to a 50' extention cord of 12 wire on the welder if feed from a 50 amp receptacle and even that is slightly exceeding the Mfg's specs

Understanding as the incurred voltage drop causing the required amperage for a set amount of output to go up is pretty simple. In transformers its called "Crest Factor". In SCRs they have a "decay time" or power dissipation time necessary to keep the SCRs cool enough to remain in their operating limits. Reduced input voltage reduces the dissipation rate and ultimately ends up as heat in the most critical component of an inverter machine.

Will the average DIY guy burn up his machine running at reduced voltage ? Probably not if the machine is equipped with descent thermal protection

But this is from the Miller 140 Autoset Manual

Connect unit to proper input voltage or check for low line voltage.

Would the average DIY guy know for that measurement to be applicable he would need to make the measurement under load while the machine is welding - probably not

 

[sberry]

Is it a little or a lot, is it 5% or is it a deal breaker? Is this for continuous service or to zing a weld on a gate? Some things in life are not worth the math to the avg user and it could be real easy to get the impression that what he is intending to do wont work.

We run in to it on other forums, guy buys a 187 to build a torator and we got a deal going which is the best weld and tips on turning the contact tip on the mini late before I would attempt such a feat. Its a great exsercize in learning the how to and why but in the long run Aunt Etyle would be well served by a couple adequate cords at reasonable cost vs 100 ft of 12 with jobber ends that weighs a hundred pounds.

Contrary to popular internet opinion you can cut a board off with a circ saw from 100 ft of 16 wire. Loise 10 volts from 123 ro 113 and lose 10% power and 10% time and for a cut or 2 on a 2/4 it wont be a factor to saw life worth a pinch of salt. Never never ever recover the cost of the cord. Neither in saved power or tool wear.

 

[sberry]

I had never looked at a HH140 but peeked and see they recommend a 12 cord to 50 and a 10 after that. A 187 allows a 14 to 67 ft. I guess they figure you can double the output and the V drop numbers are so much better at 240

 

[Tim Fitzgerald]

OK, could a math professor please chime in and tell me wire size and recommended breaker

 

[JoeFin]

OK, could a math professor please chime in and tell me wire size and recommended breaker

Its not that simple

Really need to know "What Welder" you are thinking of to size it correctly by the MFG's specs and by the NEC as you can see in the discussion by these code experts here

http://forums.mikeholt.com/showthread.php?t=135154

Personally I think madosta had the best answer since your estimate of a 100' run to the receptacle

If you pulled #10 THHN I would personally protect it with a 30amp breaker - as most welders won't pull more than that, but since it's an arc buzzbox probably, you're best bet is the #8s at a minimum and a 50amp breaker.

This would also allow you some room to up grade at a later date

 

[sberry]

OK, could a math professor please chime in and tell me wire size and recommended breaker

You need 10 or better and a 50 for a buzzer.

 

[Tim Fitzgerald]

Thanks to everyone for your replies..., I sure did learn a bunch from y'all!

So If I go with 10 ga and 50 amp 240 set up, if ever overheated (which will never happen but just to be on safe side, would 10 ga wire trip a 50 amp breaker before wire melt down and possibly causing fire...?, I ask because I honestly dont know. I have to buy the wire so 8 ga really not that much difference