Need an electrician - 230v questions
 

I've come upon an odd situation.

My friend moved here from the UK and gave me his MIG welder that he had shipped over here because he didn't have a place to use it. It's meant for UK power, so it is 230v with a 13 amp rated heavy duty plug with a ground, a load wire, and a neutral wire. So I understand it that in the UK, there is a 230v-240v 50hz feed on that load wire, return to 0v on the neutral, and ground is ground. The machine claims it can take a 50 or 60 hz frequency.

I have a step up transformer that I use for my coffee machine from Germany, but it can only do 2000 watts, which I have used to weld with this MIG machine but the transformer is topped out and sounds like it doesn't like it. It was expensive, so I'd rather not burn it out.

So I am wondering- could this MIG be wired up to either side of a US 230v outlet- from a dryer/range plug? On those, again, as I understand it- there are two load wires and one neutral and no ground. The two loads are 115v each, but out of phase with each other which would make 230v across the two. If I wired the UK MIG welder's load wire to one of these 115v, and the UK neutral wire to the other 115v, would this work? Then the nuetral return line would not be connected to anything. I have read about people doing this with heater kettles and such but not something with a transformer in it like a welder. And then my next question is what to the with the case ground- I checked, the ground from the welded just bolts to the outer case, so I'm assuming I could just tie it to a wall panel screw to ground it.


Do I have this right? Any concerns? I know it's not 'to code' but that's not something I am concerned about. Breaker gets shut off for and everything unplugged whenever I'm not using it anyway.

I wouldn't do that...
The neutral on 230 / 50 may (don't know this for sure) be bonded to ground at the panel.
The chassis on the machine may be energized if you feed it single phase 230/240 60 on two wires.
You may need to transform up to about 400 VAC phase to phase and feed it with a proper power /neutral and ground.
You could try it but I would be careful...

contact the manufacturer.

i say yes. 240v US is still single phase.

Your title says it all: Need An Electrician

Ian

I say yes too. (Here in South Africa we also are on the UK standard of 220/230V @ 50Hz)

A normal UK plug has three prongs. One at 0V (neutral), one at ~220/230V (live), and the other being earth (sometimes called ground). What you are proposing is to couple your welder to an output that consists of a +110V side a -110V side (two separate phases tapped from the same 3 phase city supply, hence out of phase to one-another), and an earth. The potential across your neutral and live wires is still 220/230V in this configuration.

This is in any case very easy to confirm. Simply hook up a multimeter set to AC across the live/neutral pair from the socket you intend using. It will read anywhere between 210 and 250VAC, and thgis is the only important consideration here.

Oh yes, your neutral is never connected to earth, as this will most definitely trip your breaker whether the device is switched on or not. The reason for this is that neutral and live actually take turns at being live due to the fact that you are dealing with AC. Convention dictates that the side identified as live (red/brown in the UK) is always switched, whereas the neutral side (black/blue in the UK) is continuous.

Try to find the documentation for the welder and wiring. If the 'neutral' is actually a neutral, and not the other half of a 230/115 line like we have here, you can have a very real potential for shock, short to ground, etc.

It may be as simple as removing a jumper or re-arranging wires in the plug.

Pull the cover off, most likely there is a schematic on the inside of the cover. Try to get a good pic of it and post it.

I'll try but I'm not sure if I can help, but whoever can will need to see this.

Please don't let this become a "before and after" thread. :eek:;)

contact manufactuer. they are the only ones that know for sure

I'm going to ask this question for you in the electrical forum on the Garage Journal. There are come crack sparkys there.

And you can follow the answers here.

I pulled the cover off the welder. The ground goes to chassis. the Neutral goes to the power electronics of the welder and does not have continuity with ground. So I see no reason why it would not be safe.

It is a simple, off brand welder so I'm not sure if I can find documentation on it, but I'm looking now.

How is an electrician going to know how his welder is wired internally?

Mike, so many of the welders made nowadays do in fact have sensing circuitry to accommodate different power schemes. Sounds to me as if this may be the case. But, there should be some documentation in the unit. If not, type in the brand and model no. to Google to get cross reference to brands and then to discussions of same.

And hang on for a bit for the GJ'ers to get this going. It just came up live over there (after the automatic display delay all these forums use) and already has garnered 25 views.

Pulled this pic of the inside from another forum- this is the machine, it is a SIP Migmate 150
http://www.mig-welding.co.uk/forum/a...1&d=1271444280

The input wires are at the bottom right- a brown, a blue, and the yellow/green come from the mains cord. The yellow/green is the ground and goes straight to the chassis.

The brown and blue were load and nuetral labeled. It is these two that expect a +230v, -0v connection. I'm going to be giving them +115v, -115v. Total waveform amplitude is the same, so RMS power is the same.


That is my thinking.

That appears to be an older welder with transformers. I'd hold off until you get more info. Me, I don't have a clue.

Or a transformer and a rectifier and I don't know about those either.

SIP Migmate 150 - MIG Welding Forum
"So many people have problems with this brand of machine. Plenty of clarke machines go on evilbay for about £150 and for cheap sets they seem to be well liked on here - at least they work. A "bargain" is indeed hard to resist but equally when a deal seems too good to be true; it usualy is!"

Hah! Sounds like a new HF unit would put this thing back in it's box.

Well, I just tried it and it works just fine off the dryer outlet. Thanks for posting that on GJ Zeke.

It's not the best MIG I've ever used but it does the job. Most of the work I'm going to be doing I will use my new TIG for, anyway. This thing might get used for tight spot seam stitching or just tacking things together before finish TIG-welding them.