newbie has a welder

I've never welded anything before but always had the interest to tinker around with metal building stuff so I finally bought a MIG welder yesterday. Through various friends' input who work in the sheet metal industry and research on the web I decided on a new millermatic 175 that I got at local welding supply store for $625.

I still have to wire in my outlet for it and was reading the owner's manual. It says the input voltage is 230, input amps at rated output is 20, Max recommended circuit breaker in amperes is 20, Minimum input conductor size in AWG is 14, minimum grounding conductor in AWG is 12.

I'm not an electrician but I have wired up my electrical box in my garage but doesn't a 20 amp breaker on a welder seem low? The outlet is a 50 amp outlet and I had planned on running 4AWG wire to it with a

50 amp double pole circuit breaker switch. Can this still be used without doing any damage to the welder?

Also, the 4AWG wire I have is solid copper instead of stranded. Is one better than the other?

Reply to
Mark
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Wire it up to a circuit breaker and go. Your wiring is adequate. The welder will only pull amperage when it is welding, aside from the small draw for the fan motor.

If you were to weld a piece that is 20 feet long, it would heat up, but you will be doing intermittent welds with a wirefeed with pauses inbetween, and you will not even approach popping a breaker.

Yes, it is a welder, but you are welding in a much lower amperage rating than if you were burning heavy rods. The machine is a 230v. machine, but you will rarely be welding full throttle, and mostly it will be in the lower ranges where the amp draw is waaaay under your breaker rating. If you need to weld anything thick and turn it way up and run it for a long time, you would be better to do it with rod instead because of cold lap and lack of fusion in the weld.

HTH. Try sci.engr.joining.welding for additional information and help as you progress on your learning curve. Lots of helpful guys and gals there, too.

Steve

Reply to
SteveB

Plug it into your 50A outlet and weld. Nothing bad will happen. The 50A breaker is there to protect your house from overcurrent heating and resultant fire. Your little MIG welder won't even warm up 4 gage wire a touch.

Copper, solid, stranded, no big deal. Stranded is easier to pull and (sometimes) to connect, that's all.

Grant Erw> I've never welded anything before but always had the interest to

Reply to
Grant Erwin

The 20 amp fuse on the 230V line gives you 4600 watts of power from the outlet... but you are only welding at perhaps 25 to 30 volts, so you'll have

4600 watts / 25 volts = 184 amps of output (theoretically) less whatever is lost in efficiency. David

Reply to
David Courtney

Hello David,

Your math, while correct, only applies to purely resistive loads, and does not apply to a highly inductive transformer device like a welder. What happens is that the voltage and current get out of phase, (called power factor) so you can have much higher current draw on the input of the welder versus the power output of the welder.

Furthermore, there is an issue with an oversized breaker. Could be a fire risk plugging it into an oversized breaker. You should put a 20 amp breaker feeding the outlet for the welder.

Jeff

David Courtney wrote:

Reply to
Jeff

A twenty amp circuit is big enough for your welder. In fact a 15 amp circuit ( 14 awg wire and I assume they would have you use a 15 amp breaker with 14 AWG wire ) will work because you will not be welding for long periods of time. So you can use a smaller circuit for welding. But putting in a 50 amp circuit is a good idea as you may run across a stick welder at a good price sometime.

Just as you can plug in an alarm clock in a 20 amp circuit, you can use your welder on a circuit that can supply lots more current. If you want to protect the welder as well as the wire in the house, you could either put a 20 amp breaker on that circuit until you need more current for something. Or you can put a sub panel in the garage and put a twenty amp breaker there.

I have a sixty amp circuit that goes to a plug next to the basement door. I plug my 175 mig welder into it. I use the same circuit for a stick welder.

Dan

Reply to
Dan Caster

That will be just fine.

THey just don't want to hear about using zip cords so they give min.'s :-)

Martin

Reply to
Eastburn

Yes. According to Code, the service panel breaker must be sized to protect the premises *wiring*, not the load. With #4 wire, a 50 amp breaker meets that criteria.

If Miller wants the load protected (and UL acceptance), they have to install their own fuse or circuit breaker *in the unit*. In fact they have, it has a 25 amp breaker, CB1, in its primary circuit. So don't worry about hurting it by plugging it into a heavier circuit.

Solid is better for the terminations used for circuit breakers and outlets. Stranded really should only be used with terminals designed for use with stranded wire (full crimp preferred).

Gary

Reply to
Gary Coffman

Correct, which is why you want to use a heavier wire and a heavier service breaker than would be needed for a purely resistive load.

If he's using #4 wire, a 50 amp breaker is not oversize. It will trip before the wire overheats dangerously. That's what Code says it must do. What it *won't* do is nuisance trip with the reactive load provided by the welder.

The welder has its own internal breaker, CB1, a 25 amp delay breaker, which is designed to protect the welder in case of a welder fault. Because it is a delay breaker, it won't nuisance trip like a 20 amp service panel breaker would.

Gary

Reply to
Gary Coffman

Gary, how many service entrance pannels have you wired? All the breakers I've wired for ampacities greater than 30 A have had terminals suitable for stranded wire. ie. a hole with a screw to pinch the wire against the opposite side. ...lew...

Reply to
Lewis Hartswick

i was thinking that #4 solid would be hard to work with. --Loren

Reply to
Loren Coe

...>

there are terminations for stranded wire, used by electrical contractors. they look like just a barrel, they are crimped on. code used to allow use of solder, too.

a co-worker almost got fired from GE when he connected main power to a computer with stranded wire at a test station and got a strand shorted. they had frayed out and were a bit difficult to insert. they said he should have known that the wires s/b crimped or solderd. no one else seemed to know.

--Loren

Reply to
Loren Coe

Probably well over 1,000 over the years.

Unless the hole is a snug fit to the wire to prevent the strands from spreading when loaded by the screw, which it usually isn't, that won't give a good full ampacity connection. When I have to attach stranded cable to a breaker, I use a proper size crimp ferrule over the wire first. Stranded wire needs a full 360 degree compression to achieve a proper connection.

Gary

Reply to
Gary Coffman

DO NOT SOLDER standed wire and then use any sort of pressure clamp to attach the wire. The solder will cold flow and you will then have a loose connection. The loose connection will oxidize and then overheat. Where I used to work they did an inspection to make sure that no plugs had stranded wire that had been soldered. They missed a couple of power cords, but the problem showed up a year or so later.

Dan

Reply to
Dan Caster

One way around that is to crimp the connection, and then flow solder into it afterwards. These don't loosen up after time. It's a bit of a bodge and I would never wire any power connections that way, but I've found that doing this for motorcycle wiring has two advantages: 1) the solder will wick into the stranded wire for a way, and prevent work-hardening and fracture near the crimp connector, and 2) it prevents corrosion at the crimp when the connector will be exposed to rough environment.

Jim

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Reply to
jim rozen

Exactly right. Solder is a no-no for any high ampacity connection.

Gary

Reply to
Gary Coffman

Would silver solder be even better? The reason I ask is that I have just silver soldered the crimps on a set of battery adapter cables for second son's UPS. (The free 12V gel cells are too big to fit in the case) Gerry :-)} London, Canada

Reply to
Gerald Miller

Thanks everyone for your comments. Turns out I didn't have enough #4 wire to run 3 wires the distance I wanted the outlet at so I went next door to help my neighbor who'd building a house now and we were talking about it and I mentioned I needed to go and get some wire, he handed me his leftover roll of #6-3 wire he used for his stove. I did call Miller and confirmed that I should use a 20 amp breaker, they also said a 30 would work too so that's what I used. I don't think in my projects I'll ever need it all. Hooked it all up and welded up the first thing ever last night, a small welding table. It was alot of fun, doesn't look so pretty but that will take practice.

Thanks again, Mark

Reply to
Mark

I think that silver solder would be okay. Silver solder is much harder and not likely to yield as soft solder does. Also it will not oxidize easily as soft solder does.

Dan

Reply to
Dan Caster

You might consider crimping the connection and then applying two layers of heat shrink tubing. The first is the two layer stuff where the inner layer melts while the outer layer shrinks. If you heat from the middle toward the ends, this will give an excellent seal. The second is regular flexible heat shrink somewhat longer than the first application. The net result is a well sealed connection with a flex relief somewhat like those tapered rubber ends mold on factory connections.

Ted

Reply to
Ted Edwards

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