Welder Circuit - sanity check

[jrj3rd]

? For the electricians out there


Just picked up a Millermatic 180 welder. Welder requires ~24 amps and comes prewired with a 50 amp plug.

My thought is to run a new circuit from my panel to the garage.
Run is 45' total
Will use NEMA 6-50 receptacle.
Will use 6-2 wire so down the road the next guy has matched outlet and wire.

Question is on the breaker. I plan on just putting in the 50 amp breaker, or should I size it down to a 30 amp to size it to the welders requirement??

If I use the 30 I will mark the outlet as a 30 amp welder circuit.

I should have no issue using the 50 breaker though right,?? as the welder requirement is less.

Cost is not a consideration since it is the same either way.

Should be noted that Miller says I can use a 30 amp breaker and 14-2 wire with the 6-50 receptacle (not going to happen in my house)

Thanks for any advice on this.

John

 

[Zrexxer]

You can put in #6 wire, but it's unnecessary extra cost. NEC allows derating welding circuits in Article 630. This machine runs great on a 30A circuit and #10 wire. Having a 50A receptacle is of no consequence, that doesn't govern the circuit. NEMA 6-50R is pretty much an industrial standard as a "welder receptacle." An important point to remember is that the breaker protects the supply wiring.

If it was me I'd use a 30A breaker, #10 wire, a 6-50R, and be done with it. If it makes you feel better you can label it as such:

 

[Keep]

I have the Lincoln 180 that has the same requirements as the Miller. I just ran the 50amp I do not see the reason for downsizing to 30amps, especially if you are running the bigger wire.

 

[nate379]

I did the same as I figured in the future I may want to plug something in that truly needs the 50amp circuit.

The electrician that did the wiring (was something I added into the offer when I bought the house) ran 10 gauge. All I had spec'd was a 50 amp circuit with a NEMA 6-50 plug for a welder.

I don't know how you can run 10 gauge for a 50 amp circuit, but he did. If my welder was pulling near 50 amps I would imagine that wouldn't be good for 10 gauge wiring.

 

[koditten]

I use a miller 250 and a miller 210... alot! My 30 amp crcts have never given me any trouble. The first thing I did was get rid of those 50 amp plugs and 6 awg cords on the welders. The cords and plugs were a pain to deal with being so stiff. There is no way to coil the cords up when you are not using the welders. I have no Idea why miller does this with their plugs and cords. It just confuses the hell out of everyone.

 

[Torque1st]

The second time my 50A welder outlet was used was by my father when he stopped by the house for a couple days in his RV. I also put the #6 extension cord I made for the welder to use. Spend the few $ to make it a true 50A outlet. You never know who might show up to use it. I don't know if the use was quite legal because there was no real ground. Dad had the RV adapter plugs to make it work.

 

[nissan_crawler]

I ran 6/3 w/ground to all of my 240v outlets. I put a breaker sized for the item, though. i think the largest breaker right now is actually 30 amp. however, if I NEed 50 amp to an outlet, it's a cheap breaker swap. If I need to hook up a newer appliance or something with the 3 wire w/ground, it's a simple outlet change.

Did the wire cost more now? Sure. Will it be much cheaper than doing it later once everything is covered? You bet.

 

[Ironcrow]

If I was doing it, I'd make the whole circuit 50A; breaker, wire, receptacle. No label on the handy box. A guy looks at a NEMA 6-50 hanging on the wall, he's got a 50A circuit.

What if I come visit the OP with my welder? I've got a NEMA 6-50 plug too. But, my welder draws 42A.

 

[jrj3rd]

Since no one has come up with any good reason not to just go 50 all the way (cost is not a good reason) and Ironcrow thoughts parallels my own as far as visitors or next users, looks like I will be running some new wire this weekend and get this project completed.

Thanks for all the comments.

If anyone has any further comments on why not to just run the 50 all the way I am willing to listen, but at this point saftey issues will be the ones that could sway me, and I am not seeing a downside to this plan.

Thanks

John

 

[sberry]

If I was doing it, I'd make the whole circuit 50A; breaker, wire, receptacle. No label on the handy box. A guy looks at a NEMA 6-50 hanging on the wall, he's got a 50A circuit.

What if I come visit the OP with my welder? I've got a NEMA 6-50 plug too. But, my welder draws 42A.

If I ran a 6 wire I would breaker it at 50A also, the 180 can run on circuits to 50A, the 30 in the manual is a must if you are using the minimum of 14 wire, no one thinks its a good idea though. 12 or better to this machine.
In a Buds garage where it might be piped or visible Romex it doesn't bother me to run a piece of 10 wire to a welder outlet and a breaker to 50A, which actually may be one size above a code depending on connected load. You could run 2 180 class machines each connected with 12 wire to a 50A breaker.
There were millions of code legal 50A protected circuits with a 10 wire to an outlet for a welder installed back in the day. Lincoln sold millions of buzz boxes that got connected to the range side of a fuse panel. About the only common thing in an old home ever required an 8 wire is a range/oven.
A freebie I did recently was to add outlet on the hoist for MIg welder, only material I needed was outlet and wire about a foot long.

 

[sberry]

Yes, your welder may draw 42A but it doesn't make it unsafe to use on a 10 wire with a 50A breaker.

 

[walrus]

Yes, your welder may draw 42A but it doesn't make it unsafe to use on a 10 wire with a 50A breaker.

It might if it was continous but thats probably not going to be the case

 

[sberry]

This is pretty much DIY crowd so investment in a roll of 10/2 will run pretty much any equipment found in small garage. Air comp, air cond unit, hoist, welding which is 99.5 short circuit or 1/8 electrodes.

 

[walrus]

This is pretty much DIY crowd so investment in a roll of 10/2 will run pretty much any equipment found in small garage. Air comp, air cond unit, hoist, welding which is 99.5 short circuit or 1/8 electrodes.

I understand, the key to your statement is, pretty much, which isn't 100%, thats all I was saying.

 

[hidollartoys]

It is just what Zrexxer stated. As per code, welder circuit conductors are allowed to be "derated". BUT, the code specifies a maximum over current protection device (breaker) value. If you exceed this value on the circuit protection you are required to provide "local" over current protection that adheres to the code. While the OP may not ultimately be in violation of the code, it is somewhat shortsided to make rash general comments concerning welder circuit ampacities. The article for welders sets a minimum conductor size AND a maximum breaker size.

 

[brownbagg]

only thing a circuit breaker does is protect the wire in the house, it does nothing for the welder. breaker is just to keep the wire from overheating and catching fire. you could run the welder off a 100 amp breaker if the wire was heavy enough. the welder is only going take what its needs, you said it was 23 amps. Myself I go 50 in case you need to crank an a/c or maybe car lift later in life.

 

[hidollartoys]

only thing a circuit breaker does is protect the wire in the house, it does nothing for the welder. breaker is just to keep the wire from overheating and catching fire. you could run the welder off a 100 amp breaker if the wire was heavy enough. the welder is only going take what its needs, you said it was 23 amps. Myself I go 50 in case you need to crank an a/c or maybe car lift later in life.

You are only half right. True OCPD is to protect conductors. In addition, article 630 requires an OCPD for the welder if the circuit OCPD is in excess of 200% of the welder "maximum rated supply current at maximum rated output". This is only really an issue when considering welders that are not manufactured with an "onboard" OCPDs.

Also, A disconnect is also required when a welder is not equipped with a means of disconnect that is not an integral part of the welder. This can be a switch or circuit breaker. And is implied that it is located within line of site of the welder (visible of) and within 50 feet. Just another issue that should be considered in the "welder circuit".

Like I stated earlier. the OP may not be in this situation but it is important that everyone understands the implications of making broad. unimformed statements concerning branch circuits until ALL info is considered.

 

[sberry]

I am kind of confused a bit here now too. These welders come with a double pole switch in them. They also come with a cord to provide disconnect. As for the wire breaker biz as it pertains to this machine, it is allowed to be ran from breakers to 50A as per its NEMA or UL or whoever. The Max breaker that is listed in the manual applies if the minimum wire is used, once he exceeds that (14) he can use a 12, which is what the cord on it is he can use it on a 50A circuit. He doesn't need to provide additional protection.
The OP was on the right track, it seemed he had only one basic issue, if he wanted to go above the code and minimum standard for this machine, he would have greatly improved by going 10, 2 steps and his issue is if he wants to flush money, he can, wont hurt a thing except more difficult to install, short run wouldn't make a deal of cost if he did go big but he dont need it.
If a guy is making this a dual purpose circuit, other than a welder then he needs to use a heavy wire like Torque does with the motor home. I also label mine, It doesn't scare me to run a circuit when I add a piece of equipment. Tailor it.

 

[sberry]

A little MIG of that class will run from 12 wire, 20, 30, 40 or 50A breaker on it and make it a legal install. You are allowed to run a 14 wire but must limit the over current to 30A.

 

[ilateapex]

I have done something similar in my garage and added a "general use" 240 receptical with #6 wire. It will be used for the welder as well as other things. Right now i am using it to plug an electric unit heater into. The heater needs a 30 amp breaker so that is what I used to protect the heater. I have a 50 amp breaker right below it in the panel for a easy change.

My understanding is that some equipment only want to be on a max breaker size. This helps to protect the equipment. My heat pump comes to mind. The old one was on a 50 Amp breaker and the new one said max 20 Amp. I changed it even though my HVAC guy did not plan to.

My question is how to you fit #6 into a 30 Amp square D breaker? I have done this but wonder if I did it right.

Michael

 

[hidollartoys]

I am kind of confused a bit here now too. These welders come with a double pole switch in them. They also come with a cord to provide disconnect. As for the wire breaker biz as it pertains to this machine, it is allowed to be ran from breakers to 50A as per its NEMA or UL or whoever. The Max breaker that is listed in the manual applies if the minimum wire is used, once he exceeds that (14) he can use a 12, which is what the cord on it is he can use it on a 50A circuit. He doesn't need to provide additional protection.
The OP was on the right track, it seemed he had only one basic issue, if he wanted to go above the code and minimum standard for this machine, he would have greatly improved by going 10, 2 steps and his issue is if he wants to flush money, he can, wont hurt a thing except more difficult to install, short run wouldn't make a deal of cost if he did go big but he dont need it.
If a guy is making this a dual purpose circuit, other than a welder then he needs to use a heavy wire like Torque does with the motor home. I also label mine, It doesn't scare me to run a circuit when I add a piece of equipment. Tailor it.

First of all a cord and plug is not considered a disconnect execpt on some VERY small load items and motors and is specific to the application. Definately not welders. Second, if the welder is equipped with a "switch" to turn it off and on, that is considered a disconnect. Third. cords are considered "fixture wires" per code and are allowed to be smaller guage than the circuit conductors that feed the device and is also specific to application and amp rating of the device. Cord AWG is not a guage for the required circuit conductor size. Fifth, as I stated earlier the circuit for welders per article 630 is governed by the MINIMUM conductor size and the MAXIMUN OCPD rating. Wire size does not govern the allowable OCPD rating. If you were to read article 630 you would understand the issues. What concerns me is the arbitrary use of wire size dictating breaker size in ALL branch circuit applications. The code allows derating conductor sizes and OCPD devices for some troublesome branch circuits but you must understand the implications of following only part of the derating process for a particular branch circuit. And sixth, the literature that is provided with the machine(any machine) is only as good as the code requirements at the time of manufacture. I would suggest it is prudient to do the homework to determine if the manufacturing specs that you are using have any credibility at the time of the equipment install. AND lastly I stated the OP may not be in a situation where the conductor and OCPD is not code compliant. It is possible that he exceeded the minimum wire size requirement(a good thing) and as well exceeded the max OCPD size(not a good thing). For welder circuits the wire size does not dictate the OCPD rating.

I am not trying to argue or pooh-pooh any DIY efforts but just inform of the potential issues for choosing some "rule of thumb" approach without understanding that there might be potentially dangerous results. It is better to understand the issues than defend a position because "that is the way we have always done it". In this particular issue a simple review of article 630 would shed some light on this issue. Far be it for me to suggest a simple solution to the argument.

 

[sberry]

I am not saying wire size dictates ocpd but there is an allowable nema and code standard for cord, max for a number 12 is 50. The machine comes with 50A plug, it must have the internals to deliver short circuit protection for 50A circuits. What protects the wire is applied load, breaker ain't got squat to do with it. Like a fixture wire, 100 watts on a 16 wire to a 12 breakered at 20A. Device only draws 1 amp, the fixture wire needs to be heavy to not overheat at that load and good enough for fault protection.
They would have put a 14 cord on this machine but needed/wanted it to be able to run from 50A welder circuits.

 

[Skyline]

I use a miller 250 and a miller 210... alot! My 30 amp crcts have never given me any trouble. The first thing I did was get rid of those 50 amp plugs and 6 awg cords on the welders. The cords and plugs were a pain to deal with being so stiff. There is no way to coil the cords up when you are not using the welders. I have no Idea why miller does this with their plugs and cords. It just confuses the hell out of everyone.

Probably because those welders, especially the 250, can pull more than 30A if used at full power. I use my Millermatic 250 all the time on a 30A circuit too, but I also know I can not crank it all the way up without potentially blowing the fuse. Still, I know I'm good to about a 1/2" thick steel weld...more than enough for me.

 

[sberry]

A Lincoln buzzer, 12 wire 50A breaker legal circuit. Change the breaker to a 60 we have to follow with a wire change. If we were to tap a 100A service we need an 8 wire. Can still use the 50A hwd, the machine will burn up long before the wire, right till it melts and shorts.

 

[sberry]

Yes, the MM250 is designed for 50A service. It might even ask for number 8 in the manual, it and the 251 one of the only machines in the 50A class to do so, Lincoln spec 10 for their 250's.

 

[hidollartoys]

Again.... First, I can not find anywhere in the 2005 code where 12AWG cord is good for 50 amps. Table 400.5(A) and 400.5(B) max allowable ampacity for 12 AWG cord is 35 amps.


The application of wire size for welder circuits is determined by the effective supply current, the corresponding duty cycle and the supply no load current. It is calculated using the formula on page 508 in the 2005 code. If you lack the required info to determine the value mathmatically you can use the Table 630.11(A) also on page 508. This table is based on duty cycle and the rated max primary current.

For the OCPD, the value of the device shall not exceed 200% of the conductor ampacity. All the smoke and mirrors that you have presented before is only superseded by the actual code requirements. I am not sure why some here continue to use the "rules of thumb" without a true understanding of the implications.

If you utilize the wire size to dictate the OCPD you can oversize the OCPD. If you use the "always done it this way" approach you can also mis-size the wire and the OCPD. The sizing requirements are specifically basesd on the particular welder in question and not on the "way we have always done it". Upsizing the wire is usually a good thing, to a point, but in this instance since the OCPD must is sized based on the conductor size it is imperative to accurately size the wire. If you over size the circuit you are required to provide OCPD at the welder that is not greater than 200 % of the "maximum value of the rated supply current at the maximum rated output" or essentially the max amp input at the max output.

This is starting to get just like the motor branch circuit sizing discussion that grew out of a compressor wiring question a month or so ago.

 

[Charles (in GA)]

My question is how to you fit #6 into a 30 Amp square D breaker? I have done this but wonder if I did it right.

Michael

Strip it as shown on the strip gauge on the side of the breaker and shove it in and tighten the screw. True, its very little (short) wire sticking in the breaker, but properly tightened, it will stay and make all the necessary contact.

The breaker will have marked on it what sizes of wire are allowed to be used in it.

If by chance it doesn't have a strip gauge on it, strip it back and shove it in till it stops when the end of the wire butts against the breaker body, and make sure the insulation is stripped back far enough to clear the wire clamp.

Charles

 

[ilateapex]

Strip it as shown on the strip gauge on the side of the breaker and shove it in and tighten the screw. True, its very little (short) wire sticking in the breaker, but properly tightened, it will stay and make all the necessary contact.

The breaker will have marked on it what sizes of wire are allowed to be used in it.

If by chance it doesn't have a strip gauge on it, strip it back and shove it in till it stops when the end of the wire butts against the breaker body, and make sure the insulation is stripped back far enough to clear the wire clamp.

Charles

My 30 amp breaker has a screw in the middle holding down a plate where you put the wire on either side of the screw. It does not have the hole in the middle with the lug that squeezes the wire. I think the 30 amp breaker says max #8. I understand the strip gauge and such but the wire will not fit on either side of the screw.

Michael

 

[sberry]

Again.... First, I can not find anywhere in the 2005 code where 12AWG cord is good for 50 amps. Table 400.5(A) and 400.5(B) max allowable ampacity for 12 AWG cord is 35 amps.

You wont find it, its allowed to be used on circuits with 50A ocpd, different than max allowable ampacity. its in 430 maybe,,, cords and caps.

 

[sberry]

For the OCPD, the value of the device shall not exceed 200% of the conductor ampacity.

No one is arguing this point, we actually agree with that.

The sizing requirements are specifically basesd on the particular welder in question

Again we agree on this.

If you over size the circuit you are required to provide OCPD at the welder that is not greater than 200 %

we can agree on this too, a service main is 200 so we put a 50A breaker for the welder. I am not sure what your issue is?
This is why I try to explain in plain English, for the 180 class feeder, if you use the minimum wire lists in the OM you must reduce the breaker, simple as that.

 

[sberry]

This is also why when there is a question we dont suggest as a first answer to "go read the code book"

 

[hidollartoys]

You wont find it, its allowed to be used on circuits with 50A ocpd, different than max allowable ampacity. its in 430 maybe,,, cords and caps.

Again you are referring to derating a conductor based on a particular application and this does not justify a broad based comment. Article 430 pertains to motors and we already beat that dead horse in a previous post. With motors the conductor is based on the table amps per the code and the OCPD is allowed to be (in some cases) significantly larger than the ampacity of the wire. Welders are not motors. Two distinctly different types of loads and delt with two distinct ways in the NEC.

There are conditions where "tap" ampacity is allowed to be significantly less than the feeder conductor and feeder OCPD ampacities. Welders with cord and plug connections are not considered "tap" applications. Welders are fed with branch circuits and cord and plug assemblies are not considered to be part of the branch circuit.

You have also misunderstood my statement concerning oversizing the circuit and the need for max 200% OCPD at the welder. This OCPD is required in addition to the branch circuit OCPD. I suggest you actually read Article 630 in the 2005 code. It might shed some light on the issues that I have presented.

 

[sberry]

Again, this would only apply if the first ocpd was greater than 200%, as in a group of welders on the same feed. If we have 2 units, say 180 class feeders, each suitable for use on circuits to 50A ocpd, each draw 25A, we do not need secondary protection, we only need wire heavy enough for the load and to provide for short circuit protection.
You are reading each welder, etc. All this is moot to this crowd. They are not ganging 200A wire feeders on a 400A busway.

 

[hidollartoys]

This will be my last post on this issue.

The OP has one welder on one branch circuit. Asked if his thought process was right. Other posters made recommendations based on what they have or will do. My point was: If you arbitrarily use the 50 amp OCPD and 6AWG "sizing method" you could open yourself up to a host of issues that need to be addressed with additional protection devices( IE other OCPDs and disconnects). This issue is just like motor branch circuits. The conductor and OCPD sizing is specifically based on the particular welder in question, not some "that is the way my bud did it.
THATS ALL!

 

[sberry]

We aint talking about how my bud did it, we are talking about a legal install for this machine, if he sticks a 6-50 and a 6 wire on it with a 50 whats more to know?

My point was: If you arbitrarily use the 50 amp OCPD and 6AWG "sizing method" you could open yourself up to a host of issues that need to be addressed with additional protection devices( IE other OCPDs and disconnects).

How can we miss here? The machines in this class, (we know its a 180) come with 50A plug rated to run from 50A circuit? The guy doing this job has no more "host of additional issues" All the bases covered and then some.
The only way this guy needs to add any additional ocpd protection is if he makes part of the supply circuit 14 wire. He needs no additional disconnect either as the machine has a double pole switch.

 

[sberry]

This machine comes with cord and plug for 50A service, can be plugged in to any legal 50A circuit. The operator dont need to know anything else.

 

[Ironcrow]

sberry sounds right to me. I don't understand what hidollartoys is talking about at all.

 

[sberry]

I understand where hidollar is coming from, I think he perceives I am using wire size to determine breaker size but not really, the wire size is determined by calculated load as per machine as he suggests. After that there is a max breaker allowable. Little wire feeds have their own thermal even, not only to protect the internals but to protect the incoming wire (usually cord) when these are connected to circuits with larger breakers. As was noted earlier that this conversation pretty much applies to factory supplied cord type machines commonly used by this crowd, a guy drags home a couple 300A synchrowaves or specialty machines then other calculations are in order.
As I recall one of the original questions might have been was did the electrician gyp the guy with a 10 wire on a welder circuit or make it unsafe. Basically no, the 10 is sufficient for 50A factory cord connected units found in home garages.

 

[mikeyr]

I just went trough this this very weekend. I wired my 220v 30 amp compressor with 10gauge as required but I plugged in 3 plugs in my garage for various 220 tools, TIG, powder coating oven, table saw and other stuff. I wired it all with 6-2, it added $130 to my costs but I feel better knowing in the future I can put in anything anywhere. My electrician was telling me I was wasting money. I was planning on leaving the 50 amp breaker in and he was telling me I should put in the proper sized breaker, which I am ok with.

I will sleep way better at night with 6-2 behind my walls in the garage and knowing I can move equipment in the future with ease as I get new toys.

 

[Keep]

Wow I guess the #6 I used for the 50a welder circuit is overkill?

If 30a requires 10/2, how can 50a also use 10/2? I remember asking the inspector while he was here about wire sizes and I cannot see 10/2 passing on a 50a circuit At least not around here.