please help...

[toofazt]

I have a Millermatic 251 that is supposed to hook up to a 50A 250V, 2-Pole, 3-wire grounding, NEMA 6-50. The plug and receptacle I have is a 30A 125/250V, 3-Pole, 4-wire grounding, NEMA L14-30 coming from my electrical box with 2-30A breakers... will this work? And what does 2-pole and 3-pole mean? I don't know much about electrical things so any help would be greatly appreciated! Thanks

[Sandy]

When they talk about 'poles' they are referring to the actual current carrying blades and does not include grounding posts/lugs/blades/poles. So when they say "two pole grounding" they mean there will be two blades that are current carrying and one of a different shape that will be grounding. Three pole grounding would have three blades that do or will on occassion carry current and one for the grounding. Your welder needs two hots and a ground, hence the 6-50.

From what little I know about MM 251's I see they require 42 amps input for maximum output, so no that double 30 isn't going to cut it for high end use.

As for the adequacy of the wire that comes from that double 30 to the 14-30 you're talking about, you'd have to see what size and type it is to really get a good ahndle on what the next move is.

[MAC702]

Your machine wants a little more juice to get out of it what it can do.

Best option is to run new, dedicated circuit with #8 copper wire to a NEMA 6-50R receptacle. Two #8 hots and a #10 ground would be fine. 50A 2-pole breaker.

[toofazt]

Well, I tried to hook up the welder to the L14-30 and it doesn't work... It won't even turn on. I don't know if I hooked the welder up wrong or it's because of the different power? My dad's friend did the wiring also, so that could be the problem....

[Sandy]

Just making stabs assuming the existing is correct or hoping it all works out can have some bad endings sometimes. You could have easily ended up energizing the case of your welder. There are a couple of bad scenarios after that. You need a meter for these kinds of things.

It sounds like you don't really have any expert help handy. I'd shell out a few bucks for some DIY books or hire some advice.

[MAC702]

I agree with Sandy. That receptacle should at least give you power to run it for smaller projects. Can you verify what links the machine has been set at for input voltage?

[toofazt]

I thought it should at least power it... My brother said he checked the outlet and there IS power coming from it. I have the links set for 230V (a link on the first two prongs and a link on the second two prongs).

On the L14-30 plug there are four wire spots. They're marked x,y,w, and ground. I have the black and white wire in the x and y spot, the green wire in the ground spot and nothing in the w. It doesn't matter if the black and white wire go in the x or y spot, does it?

I'm big into DIY, but I don't want to fry a $1500 welder or electrocute myself by making a mistake!

[MAC702]

The wires seem right. Where did you get the machine? Have you seen it work before? Can you try a different receptacle?

[toofazt]

I got the welder from www.cyberweld.com I don't have another receptacle...

[Sandy]

You have a volt meter? Number one step, no matter how silly it seems at times, is to verify the source. Or perhaps you've plugged your dryer back in to power.

[toofazt]

I have a volt meter. What do you mean "verify the source"?

[Sandy]

Originally Posted by toofazt@gmail.com

I have a volt meter. What do you mean "verify the source"?

After years of chasing my tail on rare occasion I've learned to check every little detail no matter how silly it seems and no matter how sure I am that it doesn't need checked, check it anyway. Prove it twice is my trouble shooting method. By verify the source I mean is, prove once again that on the existing receptacle, what you believe to be a hot blade is hot, then the other blade that should be a hot one is truly hot. You'll be using the ground lead to do this. Then if you've built an 'adapter cord', plug it in and repeat that process. Then you would know that the AC is not only on the cord but on the right lugs. If it were my machine, and the adapter was wired the way I was pretty sure it should be then I would pop the hood on the welder, and with it plugged in but turned off verify that each hot was hot and the ground was continuous right to where the factory cord connects/merges with the internal workings. These are generally either as spade type connection or a crimped wire nut. Easy access with a probe. If It is hot inside but doesn't fire up when turned on then you have to decide whether you want to chase it a little farther or refer it back to the supplier.

[toofazt]

Thank you for the info, but honestly I don't really know what your talking about I don't know much about electronics. Are you saying test the receptacle by putting one probe on the volt meter in one of the openings that the plug goes? Sorry if I don't make sense, I'm just trying to figure it out.

[Sandy]

Are you saying test the receptacle by putting one probe on the volt meter in one of the openings that the plug goes? Sorry if I don't make sense, I'm just trying to figure it out.

Yeh, you got it. We'll call it a 240 volt circuit just for a common starting point. A 240 is merely two 120's combined. With one probe of your meter hooked (poked into) to the supposed ground slot, put the other lead into one of the x or y slots (supposed hot). You should read 120 volts on the AC setting. This means you are reading 120 volts to ground. If it is there then leave the ground probe where it is but move the other probe to to the other supposed hot slot. You should read 120 volts to ground there. Here's the prove it twice part. If both of those read 120 volts to ground then put the probes, one each into the known hot slots and you should read 240 across the two.

Now plug in your adapter cord and repeat this at its other end. Making sense?

[toofazt]

Yes I get what your saying now, thanks. The only thing now is I don't know how to use the volt meter! It's a RadioShack Digital Multimeter... I don't know what to set it to so I can test.

[toofazt]

Ok. I think the V setting is for ac. I got readings from ~0.273V, ~0.495V, ~0.550V. That's not even a volt of power though, is it?

[Tailshaft56]

You may be on a DC scale. There should be a setting marked VAC (Volts AC).

[toofazt]

Here is my volt meter if it helps...

http://img.photobucket.com/albums/v2...8/DSC00186.jpg

[MAC702]

A digital multimeter is a good tool, but is not the most reliable for troubleshooting. But that's only an issue if it DOES read 240V and you still get no power, as sometimes they read a voltage that would not be there with a load applied.

But make sure that it is not only set for Volts, but that you toggle it to AC. Most are at DC by default when first put to the Volts setting. Then, follow Sandy's procedure again and let us know.

[MAC702]

Originally Posted by toofazt@gmail.com

Ok. I think the V setting is for ac. I got readings from ~0.273V, ~0.495V, ~0.550V. That's not even a volt of power though, is it?

Power is measured in watts. You're measuring voltage, not power. We know what you meant, but you might as well learn the terms, too.

[toofazt]

So did I have it at the right setting. The V with the marks over it (the first setting in the pic)?

So the ~0.273V, ~0.495V, ~0.550V is in watts? Do those reading sound correct?

I don't know how to measure the power after the receptacle box... I have the box wired from my main breaker box. I have a plug on the end of the power cord for the welder. I plug that into the box. Would I touch the probes to the links on the welder to measure the power?

[MAC702]

Only when the unit is ON will you know if it you have it at the right setting. The dial will be set for VOLTS (you are not measuring power (which is watts.)) After setting it for VOLTS, you will use the yellow button (probably) to toggle between AC and DC. This should all be explained in the manual that no doubt came with your meter.

You are still measuring VOLTAGE; don't call it "power." Sorry for the confusion.

Using your meter's manual if necessary, verify that you are measuring AC and not DC voltage, then get back to us.

We'll concentrate on the receptacle in the wall, making sure the meter is working as we need it, before moving on.

[Sandy]

Hey guy, do a test in another receptacle in the house. ANy receptacle that's easy anywhere. It's tough to tell from the pic but it looks like you meter might be auto-ranging for the AC/DC selection as well as the voltage range of either.

In the kitchen, put the black lead in on the left slot (nuetral side) and the red lead in on the right hand slot facing the receptacle (hot side). You may need to wiggle them around a little as one doesn't always make metal to metal contact. You should read 120 volts AC. Then leave the red in the left slot and move the black lead down to the round ground slot. You should again read 120 VAC. Now you proved to yoursellf you are able to read VAC.

Then go back to the receptacle in question and do sequence we discussed. Ground to X should = 120VAC. Ground to Y should = 120VAC. X to Y should = 240VAC.

Then a couple of additional steps. It's not like those slots are a long ways apart, right ?? Putting the black meter lead in the "W" slot measure to X then Y respectively with the meter lead. Remember to check for the feel of probe to metal. There is a remote chance that that receptacle is a four prong wired with three wires, configured as X , Y and W ???????

I know little about modern welder circuitry but I'd guess that any welder with a printed circuit board and control circuitry won't even turn on without that ground reference. I doubt that switch in in series with the load. Of course just random guessing now. Need to be positive that that receptacle is hot and wired right first.

Hope this helps.

[Roy Hodges]

the "left & right" slots might confuse him. I have seen a lot of recepticles installed upside down. Sorry to be a wet blanket

[MAC702]

Not only are you NOT a wet blanket, Roy, but in many of our industrial installations, the old upside-down is the new rightside-up. NEMA 5-15R and NEMA 5-20R receptacles are starting to move to ground-up to be consistent most of the larger receptacles. It'll be a long time before the average person accepts this in their home, though. Usually now, one upside-down receptacle indicates a switched receptacle or something.

I didn't even think of Sandy's idea, though, to verify knowing how the meter works. Make sure you get nominal 120V from a standard household receptacle.

But the left-right thing is moot anyway because it doesn't matter what color goes where in AC voltage measurements.