Help me Wire a Full KVA Adapter Plug

[houlibar]

I need to make an adapter plug so I can run a plasma cutter off of an engine drive. The engine drive has the 240V 4 prong NEMA 14-50R receptacle and the plasma has the 3 prong NEMA 6-50R plug. I'm going to try and get the parts from the hardware store tomorrow. Do I just wire it POS, NEG, GRND and leave off the NEUTRAL? The ground is the half-round pin on the 4 prong outlet, correct? So the half-round pin on the 4 prong gets wired to the round pin on the 3 prong?

[GWIZ]

First.
You may want to check with the manufacturer, if its ok to connect your plasma cutter to your generator.

The electronics inside your plasma cutter may require a more stable supply of current.
======
R= receptacle
P= Plug

6-50R is a receptacle
6-50P is a plug

Look closely I'm guessing it will plugin without any adapters.

[houlibar]

Yes, my LWS knew I was going to run it off engine drive. They were going to set me up with the adapter plugs, but they were out of stock of the Eagle 21-S which was the 4 prong. Said I should be able to get the parts this weekend at a hardware or electrical supply house. It definitately won't work as is. I just need to be certain how to wire the two plugs together when I get the parts.

[cutter]

Originally Posted by houlibar

Do I just wire it POS, NEG, GRND and leave off the NEUTRAL? The ground is the half-round pin on the 4 prong outlet, correct? So the half-round pin on the 4 prong gets wired to the round pin on the 3 prong?

Well Scott, in the first place with 240 volts AC you don't have postive or negative; you have 2 hots, 1 neutral and a ground on the 4 pin plug. The 2 hots should be the 2 outside pins. You need to know a little more information but I think your plasma cutter would need the 2 hots and neutral. Check your schematics to be sure.

[Sberry]

The plaz needs 2 hots and the ground.

[houlibar]

Originally Posted by cutter

Well Scott, in the first place with 240 volts AC you don't have postive or negative; you have 2 hots, 1 neutral and a ground on the 4 pin plug. The 2 hots should be the 2 outside pins. You need to know a little more information but I think your plasma cutter would need the 2 hots and neutral. Check your schematics to be sure.

Gotcha. 120V x 2 = 240V. So the consensus is leave off the neutral and wire the half-round which is the ground on the 4 prong to the round on the 3 prong which is also ground. Yes?

[MAC702]

I made mine with the Leviton build-it-yourself receptacles and plugs at Home Depot. You only need a 3-wire cord, and you can make it an extension cord at the same time if you want.

As mentioned, there is no positive and negative. This is AC and both hots have 120V potential to ground, and 240V potential to each other.

With the Leviton style I used, you do not even need to install the center flat prong, which makes it 25% easier to push in and pull out of the generator.

[houlibar]

Thanks for the tip Mac. I'll look for that at Home Depot or Lowes. I scrounged up a good length of 3 conductor heavy wire that looks like 8 or 10. Could even be six. How can I tell? Is there a way to measure or gauge the wire? Anyway, it looks like I'll have a good expension cord.

[Shade Tree Welder]

I would recommend getting 6-3 SO cord. If you make and extension cord remember that the neutral is open.

When I purchased my engine drive it had a Nema 14-50R, I switched all my outlets in the shop and plugs on my machines to 14-50's for convenience. That way I can run them all in my shop or on the road. Several of my friends and customer's have followed suit so I can run my equipment in their shops also.

Should we discuss the operation of a center tap transformer and explain how 230/115 V single phase power is generated for home use?

[houlibar]

Originally Posted by Shade Tree Welder

Should we discuss the operation of a center tap transformer and explain how 230/115 V single phase power is generated for home use?

Sure, that would be a good topic.

Thanks for everyone's help. I've got a pigtail made up now. Couldn't find the correct plugs at HD or any hardware store over the weekend. So Monday I had the LWS get the plugs and 6' of #8. That is some heavy wire. Bundled with the insulator it's bigger than my 2/0 weld cable!