Questions for the electrical gurus in the group:
Hello all. I just joined this forum because, well, I’m a newbie and I need some help. I’ve been reading through many of the posts on this form and this seems like an informative place to be. I hope some of you experts can give me some advice.
I guess we should start at the beginning, where there is good news and bad news. The good news is I just bought a TIG machine and on the verge of becoming a novice TIG welder. The bad news is I’m about to start using it and on the verge of becoming a novice TIG welder. I’m confident that this machine will provide many hours of frustration, cursing and other lessons in patience, things I became familiar with in a college welding class about 10 years ago (and haven’t touched since). In order to emancipate the many hours of irritation trapped within the bowels of this machine, I need a place to plug it in. So, the first order of business is to do some electrical work around the shop (the wife calls it a garage).
Background: The machine is a Thermal Arc 185 Inverter. It needs a nominal 230V circuit with the ability to carry 38 amps at max output and 30% duty cycle for stick welding, which I will probably never use. For TIG, max current draw is 29 amps at 30% duty cycle. I will almost certainly be operating well below these limits.
I think my two simplest options are:
1) Replace my unused 120/240V dryer plug (NEMA 10-30R) with a straight 240V NEMA 6-50R receptacle using the existing wires and 30 amp breaker. Then make a 25 foot power extension cord out of 10/3 cord so I can reach my project; or,
2) Install a new dedicated 40 amp circuit in a more convenient location near my workbench on the other side of the garage…I mean shop.
Now my questions:
1. With respect to the dryer plug option, I can’t tell the gauge of the existing wires. There is not enough sheath showing to see the gauge. It looks like 12, but not sure. I would be OK with 10 gauge, but 12 seems a little anemic for a welder that has the potential of drawing nearly 40 amps. The manual calls for minimum 12 gauge for the primary power, although the cord on the machine is 10 gauge. Any thoughts on this? Would I be violating any common electric or building codes making this kind of plug conversion without utilizing a licensed electrician? Any wiring gotcha’s I should watch out for? Should I replace the 30-amp breaker with a 40-amp breaker to avoid nuisance trips, or would that likely be unnecessary?
2. My preferred option would be to just install a new circuit in a more convenient shop location, but it looks like a difficult undertaking because of the way my breaker box is configured. I don’t see how new cord can be run to the box without tearing everything apart. My breaker box is mounted WITHIN the outside wall of my garage and wedged tightly between two vertical 2 x 4 studs. Furthermore, the backside appears to be covered between the two studs from floor to joists with some kind of sheet metal, which in turn is textured and painted to look like dry wall. For all I know, it could just all be one integral 8’ long box. In any case, the conduits run vertically within this housing to a dry wall-encased horizontal channel that runs at ceiling height along the entire perimeter of the garage to the house with no access points. All this makes it difficult or impossible to access any of the conduits or the panel knockout holes for running a new circuit. It looks like the only SIMPLE way of running a new circuit to the box would be drilling through the back of the breaker panel and that, intuitively, seems like a BAD idea. The new receptacle that I want to install only needs to be about 1 foot away from the back side of the breaker panel…so close, yet so far. Any thoughts from you electricians on the best way to add a 240V-40A circuit in this kind of situation? Is there some neat trick I don’t know about and will I have to pay a gazillion dollars to learn from an electrician? If I hire an electrician to do this for me, what kind of money should I expect to part with (you know, so I’ll be able to detect whether or not I’m being skinned).
Ok, I think that's enough fun for one day. I would greatly appreciate any tutelage you fine people can offer me.
Thanks.
Very briefly, a dryer outlet *usually* has 10 ga. wiring--good for 30 amps. The dryer breaker should also be 30.
Try making a 10 ga. extension from your dryer outlet and see if it works OK. If not, you could try a 50 amp. "range" outlet, which should have 6 ga. wiring.
My opinion based on the information you provided would be to install the new circuit. If the new outlet will be only about a foot away from the breaker panel I would think it shouldn't cost too much to have an electrician install it. Cheaper to pay an electrician than burn down the shop by using an outlet that may have inadequate wiring for what you are drawing. Undersizing an electrical circuit creates heat which in turn can create fire.
Plan on adding the circuit to handle the max that the machine will draw. The difference in the cost of the materials between a 30 amp circuit and a 50 amp will be minimal, if you hire an electrician the labor should be the same.
If I'm reading your post right it sounds like your breakers are on the opposite side of your garage wall than your workbench. You may be able to use a holesaw to cut a hole in the backside of the breaker box to run a conduit through the wall. If you do this I would first cut a square hole in the wall for access to make sure you aren't going to drill through a conduit or wire. You could make the hole in the wall the right size for a recessed box or you could cover it with a plate that the outlet is mounted to. I would shut the main breaker off before doing any cutting or drilling and make darn sure you know where the main power is coming into the breaker panel so you can stay clear of that.
Hope this helps, above all whatever you do make sure it's done safely!
Jim
Thanks for the tips guys. I decided to just take the simple route and see how it would work. Replaced the dryer plug with NEMA 6-50R, left the 30 amp breaker in and made a 10 gauge extension cord. Worked great. Everything stayed as cool as a cucumber and no breaker trips. My welding sucks, but the machine works great.
It depends on the dryer wiring, but take note that you do not want to use a neutral wire for a ground. Many dryer outlets use two hots and a neutral with no ground. You want two hots and a ground for most two pole welder circuits. If you do not use the dryer recep. any more you could probably rewire the neutral as a ground in the panel, but you must also change the recep. to match this configuration. Not sure if the code allows this due to the white or gray neutral wire color. (usually ground is either bare or green) It gets a bit confusing with neutral/ground but the main difference is a ground wire is NEVER a path for current unless something goes wrong. Current flows through the neutral busbar on a properly working circuit, so it cannot be used as the ground, even though a machine may operate when wired this way. I don't think code allows the two hots, one neutral anymore on range or dryer circuits. I think most of them have four wires to include the seperate ground path. I hope this doesn't confuse me...err... you. Oh, and the reason this happened on many electric range/dryer circuits was because some of them need a 120 volt supply for the timers and such, but need the 220 volt for the large drawing heating elements.
bzzzz--,
My incoming circuit breaker panel has all the white neutrals AND all the bare ground wires attached to the same vertical strip. Panel was installed and inspected in 1999, in Arizona.
I thiought that in the past there could be a small voltage between them because the neutrals were grounded at some distant point by the "power company", and a local ground could easily be at a diff. potential.
What is going on here?
subpanel vs. main panel. I guess other than the color of conductor and the recep. the wiring for the circuit is the the same for the main panel. If it's a sub the neutral would float and continue onto the neutral inside the main panel. The dryer circuit would need an insulated neutral as it might carry current during normal use. I've just always been told that the ground should be green or bare and never carry current. No, I am not an electrician and you should consult a licensed electrician before changing any wiring.
bzzz is right about the ground never carrying current (unless it's fault current which is the idea of the safety ground and the cause should be repaired immediately). Sub-panels typically do not have the neutral connected to the ground buss in them and it is passed through to the main panel.
I have heard instances on various forums where people describe the bare or green ground wires connected to the same buss bar as the neutral in their main panel as you describe. I am in Canada so I can't be too explicit about the regulations but where I live the grounds must be connected to the ground buss and the neutrals are connected to the neutral buss. A brass screw connects the neutral buss to the ground buss so electrically speaking they are indeed connected together. If the panel is used where they should be separate, as in the sub-panel case, then the screw is removed. So your setup is electrically the same and since it was approved don't worry about it. You just can't easily remove the ground from your neutrals but you don't want to do that anyway!
Every main panel is connected to a ground at the house which is the water pipe if on municipal water or an approved grounding electrode if you are on a well. There is no ground wire from the pole to the house.
How did it go welding up your TIG welder?
I have a Lincoln TIG 185 that came with a 50-amp plug. I have an idle 40-amp circuit and breaker in the basement, and I would like to plug the TIG 185 into that circuit while my garage is being built.
I've already hooked up my new upright compressor to a 30-amp circuit with no ill effects. Call me ambitious.
Does anyone forsee any problems with this?
Bill in Calgary
wagnerb (Bill),
Everything is working fine. My dryer circuit has a 30 amp breaker and my machine will only exceed this value under extreme conditions which I will probably never see. Also my circuit is a three wire, with one of the wires a bare ground wire. It was a very simple matter to simply replace the receptical to match the welder plug. I did have to make an extension cord to reach my work, but it is oversized slightly and will never the be weak link. The circuit breaker is still the weak link in the chain.
Steve
Thanks for the advice - I got it hooked up Saturday, and it works great. With a 40 amp breaker, I can get 120 amps of DCSP. Haven't tried AC yet, but that's enough for now.
Bill
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