240V welder circuit- no neutral

[MushCreek]

In wiring up my barn, I'll be wiring a 50A circuit for my MIG welder. There is no provision for a neutral- it's straight 240V; 2 @ 120V, and a ground. I have a choice- either wire most of the run with NM, then the last bit (in conduit) with THHN, or I can go THHN all the way. Here's the problem- can I legally (code) use #6-2 NM, using the white wire as a hot? Or do I have to buy #6-3, and just ignore the neutral? If so, it's probably cheaper to just go THHN the whole way (in conduit). I know in some cases you can tape or paint the white wire to indicate that it is a hot, and not a neutral. What about in this case? Or is it a good idea to just go 6-3 and have the neutral there 'just in case'?

Due to the location (on a pole) of the outlet, I need to use conduit and a surface mounted box either way. The choice is whether to run NM to the top of the pole in a J-box, then into the conduit with THHN.

 

[rockwithjason]

yes you can up to the point where the nm cable jacket ends. if you extend the nm cable into the last box thru the conduit you can use the white wire as a hot because it's a cable assembly, you just need to re-label accordingly. if you stop the nm cable assembly at the point where you enter the conduit then you must not use the white wire for hot.

 

[MushCreek]

I didn't think you were allowed to run NM in conduit?

 

[wyliesdiesels]

I didn't think you were allowed to run NM in conduit?

Thats an old wives tale that wont die!

NM-b is most definitely allowed to be ran in conduit INDOORS!

 

[MushCreek]

How do you terminate the end of the conduit where the NM-B goes in? Junction box? I can't just see threading it into a cut end. I want to run unprotected NM up above 8', but run it in conduit down to the box.

 

[pattenp]

You need to use the widest dimension of the NM cable to figure the area to size the conduit.

Terminate the conduit with a plastic bushing or an EMT NM clamp on the end.

 

[MushCreek]

As near as I can figure without buying the cable, I'd have to go at least 1" conduit. Do they make outlet boxes with KO's that big? The ones I have only go up to 3/4", and I know that's not enough.

 

[Beemer533]

If you are only doing the one outlet and you already have a box, just grab a uni bit and open up one of the knockouts..

This post edited by the NSA

 

[MushCreek]

It's interesting- 6-3 NM is smaller than 6-2! Since you go by the biggest dimension, and 6-2 is flat, while 6-3 is round, the rating for 6-3 is actually smaller. Dumb, but rules are rules. The 6-3 is a LOT more expensive.

As for 1" conduit; it depends on how they measure it. It actually measures 1.050 inside diameter, which gives a 40% fill of .346, meaning it could take up to a .644 cable. 6-3 runs .62; 6-2 runs .680, or technically too big for 1" conduit. Or, I can just run 6-3 (or 6-2) to a J-box, then run 6 THHN down the conduit to the outlet. We're right back where we started! If I run the THHN (just two conductors and a ground) I can probably stay with 3/4" conduit. Hmmmm.

 

[Dragfluid]

Fold the 6-2 into a "V", lube it up, shove it in the conduit, and get on with life.

 

[MushCreek]

Believe it or not, it's cheaper (for materials) to run conduit and THHN than NM. Not only that, but even four #6 wires are OK in 3/4" conduit. Also, I have a few sticks of 3/4"; enough to do the job. I found some on-line sources that are much cheaper by-the-foot than the big box stores.

 

[MushCreek]

Fold the 6-2 into a "V", lube it up, shove it in the conduit, and get on with life.

If I thought the inspector would buy off on it, I would.

 

[Dragfluid]

Believe it or not, it's cheaper (for materials) to run conduit and THHN than NM. Not only that, but even four #6 wires are OK in 3/4" conduit. Also, I have a few sticks of 3/4"; enough to do the job. I found some on-line sources that are much cheaper by-the-foot than the big box stores.

Well,,,,, yea, of course it is. Nearly as easy to run, too. That's what I did for my welding/plasma cutter circuits. That #6 stranded pulls pretty decent. Just use lotsalube.

 

[sberry]

First, what welder do you have? 250 migs are the only factory cord that needs them provided you are a professional in a heavy fab shop running large wire and special gas, replacement gun.

 

[MushCreek]

I have an older Lincoln 200. It calls for a 50A circuit, although I ran it for years on a 30A dryer circuit, and never popped the breaker. I only use gas, not flux core wire, so I never get above about 1/2 'throttle'. I might go with #8 and put it on a 40A breaker. I just like to make everything heavy duty, so there's never a question. You never know when a bigger welder might find it's way home.

 

[sberry]

8 with a 50, some of them even 10

 

[MushCreek]

According to all of the charts I looked at, #8 is rated for 40A; #6 is rated for 55A. When you go to buy the wire, that's what it says, too.

 

[sberry]

Some welders allow 50A on 12 wire. Some of the older 200 class, 20 plus years were heavier machines and needed 10 You have an owners manual for it?
Lincoln has had some strange ratings over the years but the new machines look to be rated the same as every one else, I think the 210 mvp may be a 14 wire machine?

 

[MushCreek]

This thing is huge- probably 400 lbs.; all copper wound. I think the date on it is 1983. At any rate, it doesn't matter what the welder is rated at; it's what is required to meet electrical code. The inspector doesn't care what I plug in. If I use a 50A breaker, I need to go #6 wire. If I go with a 40A breaker, I need to go #8.

 

[brownbagg]

welder dont have neturals, two hots and a ground

 

[matt_i]

The way I interpret the code, you have to wire-size for the I1max, if not specifically listed, that's the welder's rated current. But you can run a breaker sized for 2x the rated current. I'm guessing that's to prevent nuisance trips due to inrush.

I think Lincoln is typically asking for a 50A circuit. I recall a 130 Mig that I owned that called for a 50A circuit and had an "oven plug" on it, but it would clearly run on a lower number of amps. From the manufacturer's perspective, a lot of their warranty claims, etc, probably go away when a percentage of people aren't running a 20A circuit that's 500feet long with a large voltage droop at the end of the line.

 

[sberry]

This thing is huge- probably 400 lbs.; all copper wound. I think the date on it is 1983. At any rate, it doesn't matter what the welder is rated at; it's what is required to meet electrical code. The inspector doesn't care what I plug in. If I use a 50A breaker, I need to go #6 wire. If I go with a 40A breaker, I need to go #8.

The circuit can be tailored for a specific welder. But it is a real machine at 400# that's for sure. Most of them used an 8 cord I believe.
A factory cord equipped machine doesn't plug in to circuits larger than 50, re read the language. A buzzer uses or can use the same current as a 250 mig on a 12 wire and comes with a 12 cord and 50 end.
A 240 compact mig uses the same cord, 1/2 the current, can be used on a 50A circuit provided the wire is as big as the cord and is only reduced when it uses its minimum wire size of 14.

 

[Zeke]

Thats an old wives tale that wont die!

NM-b is most definitely allowed to be ran in conduit INDOORS!

Just saw this thread. Previously here on the GJ someone said that individual wires inside NM cable did not have any markings as to THHN and/or TWHN and therefore were not to code.

Frankly, I'd like to know that NM cable CAN be stripped of its sheath, properly connected to a box, LB, whatever, and continue inside a conduit.

 

[sberry]

A buzz box doesn't have any additional thermal built in. Your 200 of old is similar to the 250 today and some of its protection is from the circuit breaker. The modern compact mig has additional protection following the switch for its own thermal and short circuit below 50A. A wire 12 or larger is not being protected from thermal, a 6 or an 8 make no difference as long as its large enough for short circuit, the demand of the unit is the thermal protection for the wire.

 

[sberry]

We need someone can splain this better than I can. A weak link is the recept wire size listing and the breaker size listing. Its so much simpler to use a larger wire and as important is the connection is so much better especially with larger machines.

 

[sberry]

It will trip a 50A on thermal way ahead of overheating an 8 wire and a 10 on a manual welder too. As someone said they were running it on a 30 dryer. Millions of these were installed on 50A garage service, 50A fuses to a 10 cable and 50A outlets for welding machines.
As a practical matter today the insulation on a common cable is better than ever and the voltage 10% higher than when the standards for wire size were implemented for this equipment. A wire and cord that used to carry 43A now carries 39. Like adding a 10% bigger cord for free. In many cases cordage is sufficient at 208 as well as 240

 

[sberry]

That 200 is probably rated output at 60% but some of those old buggers would do in excess of 250 spraying 045 wire.
I have an old 130T and its the same machine they make today as a HD model that is 180, lists 8 wire and 40A. Ready made "welder" extension cords are 8. Its adequate for any thing cord and plug comes factory 50A end.

 

[MushCreek]

I have a 10 gage cord on it, and a plug that looks like a giant 120V plug. As I said, it doesn't matter to the inspector what you're going to plug into it; only that the wire and outlet aren't overloaded with too big a breaker. The outlet I have has 4 contacts for things like dryers and ranges that require a neutral now days. I'll go ahead and run the neutral, or the inspector might kick it back for not have the neutral contact hooked up. Again, explaining what I'm going to plug in won't matter to him. To install a 3 contact outlet, I'd have to buy a new outlet and a new plug end for the welder cord. They don't sell the ones that look like a giant 120V outlet in a 3 contact configuration that I know of.

I know the welder will run just fine on 40A; maybe even 30A. But what if I buy another welder? How much does a 240V buzz box draw, if I start welding heavier stuff? If I run #6, with 4 wires, I can run just about anything.

 

[wyliesdiesels]

Just saw this thread. Previously here on the GJ someone said that individual wires inside NM cable did not have any markings as to THHN and/or TWHN and therefore were not to code.

Frankly, I'd like to know that NM cable CAN be stripped of its sheath, properly connected to a box, LB, whatever, and continue inside a conduit.

What they said is correct.

The conductors in NM-b are NOT individually marked and if the conductors were removed from the NM-b sheath and used inside conduit in the same manner as THWN it would be a violation of code.

I have a 10 gage cord on it, and a plug that looks like a giant 120V plug. As I said, it doesn't matter to the inspector what you're going to plug into it; only that the wire and outlet aren't overloaded with too big a breaker. The outlet I have has 4 contacts for things like dryers and ranges that require a neutral now days. I'll go ahead and run the neutral, or the inspector might kick it back for not have the neutral contact hooked up. Again, explaining what I'm going to plug in won't matter to him. To install a 3 contact outlet, I'd have to buy a new outlet and a new plug end for the welder cord. They don't sell the ones that look like a giant 120V outlet in a 3 contact configuration that I know of.

I know the welder will run just fine on 40A; maybe even 30A. But what if I buy another welder? How much does a 240V buzz box draw, if I start welding heavier stuff? If I run #6, with 4 wires, I can run just about anything.

first off what is the model of the welder?

Second, is there a NEMA number on the plug? Take a pic and post it here.

As far as no 3 prong plugs and outlets being available, what voltage are u referring to? 240v? Sure theres 240v 3 prong plugs available.

 

[Beemer533]

I have a 10 gage cord on it, and a plug that looks like a giant 120V plug. As I said, it doesn't matter to the inspector what you're going to plug into it; only that the wire and outlet aren't overloaded with too big a breaker. The outlet I have has 4 contacts for things like dryers and ranges that require a neutral now days. I'll go ahead and run the neutral, or the inspector might kick it back for not have the neutral contact hooked up. Again, explaining what I'm going to plug in won't matter to him. To install a 3 contact outlet, I'd have to buy a new outlet and a new plug end for the welder cord. They don't sell the ones that look like a giant 120V outlet in a 3 contact configuration that I know of.

I know the welder will run just fine on 40A; maybe even 30A. But what if I buy another welder? How much does a 240V buzz box draw, if I start welding heavier stuff? If I run #6, with 4 wires, I can run just about anything.

You are looking for a 6-50R.

http://www.stayonline.com/detail.aspx?id=8952

This the one I bought for my welder....

http://www.homedepot.com/p/Leviton-...PIPHorizontal1_rr-_-203492410-_-202077691-_-N


I bought a 200A inverter based Tig and ran 8awg with a 40a breaker.

 

[MushCreek]

That's the one, but my outlet (that I already have) has a 4th prong for the neutral. The 3 prong plug on the welder cord fits it. I'd rather run a neutral (might be handy for future use) than buy a new outlet.

The welder is something like an 'SP-200', IIRC. The cord and plug is not original. I bought it from a school system auction, and it looked it had been hard wired.

 

[wyliesdiesels]

That's the one, but my outlet (that I already have) has a 4th prong for the neutral. The 3 prong plug on the welder cord fits it. I'd rather run a neutral (might be handy for future use) than buy a new outlet.

The welder is something like an 'SP-200', IIRC. The cord and plug is not original. I bought it from a school system auction, and it looked it had been hard wired.

Take a pic of all the plugs and outlets and post em here so we can help.

If your outlet is 4-wire then its either a 14-30 or 14-50...

 

[TractorJeff]

What SBerry is referring to is the rule of Welder Duty Cycle with the outlet being marked as a "Welder Only" outlet. In the case of a Lincoln 225AC (buzzbox) which can be ran on 10ga wires with 50amp fuses. This is based on the welder operating 2 minutes out of 10 minutes which is an 8 minute cool down for both the welder and the circuit.
So theoretically a 60% duty cycle machine could run on a 50 amp breaker and 8 gauge wires with no consequences provided the outlet is properly marked as "Welder Only".
Theoretically speaking.

 

[wyliesdiesels]

What SBerry is referring to is the rule of Welder Duty Cycle with the outlet being marked as a "Welder Only" outlet. In the case of a Lincoln 225AC (buzzbox) which can be ran on 10ga wires with 50amp fuses. This is based on the welder operating 2 minutes out of 10 minutes which is an 8 minute cool down for both the welder and the circuit.
So theoretically a 60% duty cycle machine could run on a 50 amp breaker and 8 gauge wires with no consequences provided the outlet is properly marked as "Welder Only".
Theoretically speaking.

table 630.11(a) covers welder circuits. Yes it depends on the welder's duty cycle and input current ratings..

http://m.ecmweb.com/qampa/code-qa-45

Code DOES NOT require the outlet to be labeled for welder use only though its a good idea...

And for the Lincoln AC225 it can be #12 THHN or #10 NM-b...

 

[MushCreek]

I went out and looked at it- the outlet is a 14-50.

As for labeling the outlet- I don't feel like trying to explain that to the inspector. They're not all that knowledgeable here, and balk at things they haven't seen before. I built my entire house, so I'm familiar with this.

It has occurred to me that I may use that outlet for other things, such as buying an old kitchen oven to do powder coating, or some such. All of this discussion has led me to think that I'm better off just running #6 THHN, running a 50A breaker, and running 4 wires so it has neutral. That way, everything is covered, and I can plug in anything that that outlet is rated for, 3 or 4 wire, 50A.

 

[matt_i]

It has occurred to me that I may use that outlet for other things, such as buying an old kitchen oven to do powder coating, or some such. All of this discussion has led me to think that I'm better off just running #6 THHN, running a 50A breaker, and running 4 wires so it has neutral. That way, everything is covered, and I can plug in anything that that outlet is rated for, 3 or 4 wire, 50A.

Planning for flexibility is excellent. The 6-50R/P doesn't have a neutral though, so you have to keep that in mind going forward. Above that you have to start going to 60A pin & socket connectors, even good-used those can start to get expensive. In my shop I have dedicated welder circuits good for the true I1max, and some 30A L14-30 twistlocks that can be used for other machinery. 14-30R/P one can buy at HD or Lowes, has the 4th pole.

 

[MushCreek]

I have a 14-50, with 4 contacts.

I have some of the twist-lock 4 pole connectors, left over from when I had my own shop ( 3 phase). I'll use them when I set up a phase convertor to run my shop tools (mill, lathe, grinder).

 

[Norcal]

I went out and looked at it- the outlet is a 14-50.

As for labeling the outlet- I don't feel like trying to explain that to the inspector. They're not all that knowledgeable here, and balk at things they haven't seen before. I built my entire house, so I'm familiar with this.

It has occurred to me that I may use that outlet for other things, such as buying an old kitchen oven to do powder coating, or some such. All of this discussion has led me to think that I'm better off just running #6 THHN, running a 50A breaker, and running 4 wires so it has neutral. That way, everything is covered, and I can plug in anything that that outlet is rated for, 3 or 4 wire, 50A.

8 AWG THHN is good for 50A, have to use 6 AWG when using NM, because it has to be used at the 60 degree rating.

 

[Zeke]

What they said is correct.

The conductors in NM-b are NOT individually marked and if the conductors were removed from the NM-b sheath and used inside conduit in the same manner as THWN it would be a violation of code.

So then, it would be to code if the original intact sheath with the wires exiting was available to inspect?

 

[MushCreek]

When I look up THHN at the places that sell it, they all rate #8 at 40A, and #6 at 55A. I'm talking individual THHN, not NM.
C.
Edit- I see what you mean. One supplier lists it at 40A @ 60C., 50A @ 75C., and 55A @ 90C. The question is whether the inspector, who only does residential will agree with that. They're used to dealing with NM.