250 Volt Hookup Question

451stroker

Hey Everyone,

I went to the electrical supply store today to buy 85 feet of 6/2 NM wire for a 50 amp, 250 volt hookup. This is only going to be used for my welder and plasma cutter. Both units are 2 wire hookup. An electrician at the store overheard me saying it was for a plasma cutter and said that I needed 6/3 because some plasma cutters use 125 volts for the digital control panel. I explained that the cutter I have does not and only requires a 2 wire hookup. The electrician still suggested that I go with 6/3, just in case I ever have a scenario where I'm plugging a device in that needs a 3 wire hookup.

I took the advice and bought the 6/3 wire.

My questions is, if I wire it for the time being with a 3 prong, 2 wire hookup receptacle, what should I do with the white wire? I assume it would just get taped off on the receptacle end, but should it still hook into the return bus on the panel?

Also, what if I just wire a 4 prong, 3 wire receptacle? Would I put a 4 prong plug on my 2 wire welder and plasma cutter and leave the lug for the white wire empty on the plug?

Which is the better way to go?

Thanks for the help.

jlmran

I would say it is better to leave the extra conductor capped off, rather than plugging your equipment into the "incorrect" receptacle, while using the "incorrect" cord cap for your equipment.

451stroker

So, leave the white wire capped off at the receptable end AND at the service panel?

Thanks.

jlmran

That's what I would do. Others may differ in their opinion.

451stroker

Also, I'm having this inspected when I'm finished. Is there any issue in not hooking up the white wire as far as the inspector would be concerned?

jbfan

I would connect it inside the panel so you don't have to open the panel again.

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"

451stroker

It's okay to do that and leave it capped off at the receptacle end?

jbfan

Not a problem.

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"

VA master elect

Any neutral or equipment ground conductor should be landed on the proper ground bar even if its for future use. Imagine the prospect of a white or bare wire contacting a hot breaker terminal screw and zapping the person at the other end!

451stroker

Would the inspector have a problem seeing a 3 wire hookup at the panel, but a 2 wire receptacle at the other end?

jlmran

The paralysis of analysis.

VA master elect

if I were inspecting it, I would peruse the paperwork for the load device and require any associated ground or neutral wire to be landed in the distribution panel.

mpoulton

I see no reason not to install a 4-wire receptacle, and switch plugs on the machines. That way you don't have to rewire anything later if you acquire anything that requires a neutral. It's no worse to leave the neutral prong unused in the plug than it is to leave the neutral wire unused in the box. In fact, I'd argue it's a better installation.

jlmran

What is so frightening or laborious about changing the receptacle in the future if so needed for a different piece of equipment?

I still say don't put a 125/250 volt cord cap on a 250 volt device. Doing that provides another reason for DIYers to be identified as 'hacks'.

Do it right and put the correct component on the cord based on the specs of the device.

joecaption

If the inspector sees an unconnect or caped off wire in a panel you can bet he's going to want to know why and where it goes. If it's connected most likly he's not even going to look in the outlet box.