Converting three prong 240 to four prong 240

converting three prong 240 to four prong 240

Yes? What about it? :rolleyes:






What size circuit is it?
What is it for?
What size wire is the circuit?
What types of cable?

These are all relavent and important questions.
A post like yours is impossible to answer, if that was even a question to begin with... :confused:

I did this today. The 4 prong is 2 220 wires and a 110 wire. The 110 is opposite the ground. I had a 3 prong 50amp head and a 4 prong receptacle on my generator. I swapped out the 3 prong for a 4 prong 30amp which matches my generator. I hooked the ground up to the top green terminal and the extra 2 wires to the right and left terminals and left the bottom one empty. I am running a welding machine off it. It worked great. TOday is the first time that I have used it though. I am not an electrician so this is the way that I did it and it worked

The 4 prong is 2 220 wires and a 110 wire. The 110 is opposite the ground. This is confusing and not correct, but oh well.



I had a 3 prong 50amp head and a 4 prong receptacle on my generator. I swapped out the 3 prong for a 4 prong 30amp which matches my generator.
So you replaced a 50A plug with a 30A? And you are not concerned about this?
I hope you are not expecting full performance out of your welder.

I had spoken with multiple different people about this. With a welding machine the amperage runs from 0 to 225. You would need the 50 amps if you were using the highest of 225. I will not be using anything higher that 125 which is about half of the total amperage. This is the reason that a 30 amp will work in this case. I used it for 1 hr tonight and it ran excellent off a generator.

Will,

Let me understand something. You chose to modify the electrical design of the generator because different people told you to do it?

Here's a bridge, jump off it. It's only a three hundred foot free-fall to the rocks below.

Since your dangerous modification is not part of this thread, I won't go any further. Please consider opening a new thread with your topic.

Ardy,

Please answer Stan's questions, thanks.

So, what's wrong with what he did. Then generator breaker will pop if he exceeds 30 Amps. Welders are one of those things that is a variable load and if your never going to weld 2" steel plate and are only going to weld 1/16" plate, you don't need the extra power. The service is limited. That's what counts.

Is the cord going to burn up? No. Is the generator going to burn up? No. Safe Yes. Might the generator breaker pop? Not likely

Why should he buy a 125 A welder when he has a 225 A welder? Or why should he buy a generator that has enough capacity to run the welder at 225A?

Inquiring minds would like to know.

Just like an electric blanket always used on low.

Kiss,

Amperage is gated by the load. If the welder is only demanding what it needs then there is no need to modify the source. It will not supply more amperage then is needed to meet the demand.

Then of course, there is the design of the generator. It was not designed to supply 30 amp. It was designed to deliver 50 amp. Changing the receptacle violates the design!

Also, the question originally posted was not about this issue.

Generator: 240 4-wire 30 A
Welder: 240 V 3-wire, 50 A

And I quote from post #3:


I swapped out the 3 prong for a 4 prong 30amp which matches my generator.

Yep, but there is a basic question of that the generator's plug is bigger than the source and it won't plug in. The welder doesn't need the neutral, so you just change the welder plug to a 4 prong and leave the neutral unconnected.

Done.

I think you misunderstood the problem. I will agree, that it was difficult to follow.

The question migh have been written as I have a 240 V 4-wire 30 A generator that I would like to power a welder which uses has a 240 V 3-wire, 50 A plug. Can I place a suitable 4-wire plug on the generator and connect only L1, L2 and GND?

To which I would reply: "Yes, providing the wires for the 50A cord will fit the 30 A plug, otherwise, you would have to change the cord or provide a adaptor cord. Some adaptor cords are commercially available.

Here is an example of adapting a 30 A service to an up to 50 A load. It's not what's required, but illustrates the principle is sound.

The question regarding the welder and generator was not written for this item at all. Regardless of being able to do something, you don't just change the design of the generator on a whim. First of all, even with a 30 amp receptacle, the generator is going to deliver 50 amp to that receptacle, not 30. What has he done to the generator to reduce the amperage to the receptcale and how has he gotten approval for these change from the vendor of the product?

The question was written by Ardy202 and we are still waiting for his response to questions posed by Stan.

Don, it's a 30 AMP generator and a 50 amp welder. You have it backwards.

Look at page 14 on this Miller document to see what the power requirements are for similar welders: http://www.millerwelds.com/om/o316s_mil.pdf

It's obvious your not attuned to the power requirements. I had to wirenut one direct to the wires entering the 30 A outlet once. The welder probably required 70 A. Worked fine for one weld of 1/4" tubing.

Kiss is correct.

Years ago I had a one man mechanic garage that wanted to fabricate his own hot rod. Thickest material was going to be 1/4 " steel. He had a 50 amp welder, and not enough service capacity with the other misc load that would be on.

So had him weld long beads while I had the unit connected to a 30 amp CB to start with, and while I watched an Amprobe, on hold setting to capture the highest amps drawn.

It cruised at 18-20 amps. Even a stuck stick only got it to 25 amps.

The trick, unknown to me how to set it, is the secondary voltage setting for the welding probes.

The 30 amp CB remains to this day.

Okay, I'll accept TK's explanation, however, it still does not answer the original post. Will was giving us observations on his setup, not answering Ardy202's post. In fact Ardy202 still has not answered questions that were sent to him.