2 or 3 wire for welding hook up

Hi
I'm going to install a 220 welder which comes with a 250 VAC 3-Prong Plug (6-50p). I need to install the corresponding 3 prong outlet. I know it requires 2 110 volt hot wires and a ground for the third prong (usually the green wire in a stove hookup).
My question is whether I need to pay extra for the 3 wire or can I just use the un-insulated copper ground wire for the third prong (which does indeed require a ground connection) and just buy #6 - 2.

Is the insulation important if the wire is hooked up as a ground?
Thanks

Elliot

 

Lots of mistakes in your post. I need to go out right now but I will answer (if no one else does) when I return.

 

No. A 240 volt welder.No. It need the two legs of your house 240.The uninsulated wire is your ground. The "third prong" is ground. You only need to insulated wires. So you can use 6-2. The 6-50 recptacle has only two hots and a ground.

You seem to misunderstand how your home is supplied with electric. It is supplied with 240 volts and a neutral from the center tap of the service transformer for your house. At your house 120 volts is derived from one of the 240 legs and the neutral. A welder is 240 volts only (no neutral).A stove hook up is not comparable to a welder hook up. A stove is 120/240 (with occasional exceptions). You are on the other hand installing a receptacle for a 240 device not a 120/240 device.

If this will be in a detached garage or other structure there are additional requirements not yet covered. Let us know.

 

A 6-50R receptacle mates to a 6-50P plug.

The wiring to it will need to have three wires. Two of those will be ungrounded ("hot") conductors. The third will be a grounding conductor.

The size of the wires is determined by the load, in amperes. We need to know how many amps your welder draws to answer that part of your question.

The wiring method needed will be determined by your local permitting authority. It will be based, in part, on the environment the welder will be in. You might be permitted to install Type NM nn-2/G, or you might need to use Type MC nn-2/G, or you might have to run conduit and pull individual conductors. They will tell the person pulling the permit when the application is made. And yes, adding a new circuit, particularly one that can supply a welder, requires a permit in almost every jurisdiction.

I don't often give this advice, but I think in this case, based on the knowledge of this work that you demonstrated in your post and the possible complexity of the installation, that you should hire a professional to do this work for you.

 

Something not mentioned yet is that welders have a special section in the National Electrical Code (NEC) that often allows for much smaller conductors depending upon the "duty cycle" of the machine. You may be able to use as small as #10 conductors for your machine IF the duty cycle is low enough.

On the other hand, installing a 50 ampere receptacle in a residential situation could be confusing to someone later on that might try to connect something that actually consumes fifty amperes, so unless it is a long run it is best to use #6 copper conductors for the two "hot" leads and a #10 copper equipment grounding conductor, all protected with a maximum of a 60 ampere circuit breaker.

 

Thanks for all the input so far, I think I understand most of it, especially the part about hiring an electrician
There seems to be a lot of different interpretations online about how to wire up this particular welder which is a Chicago Electric MIG 170AMP.

My understanding is that it requires only 20 AMPS but comes with a 50 AMP plug ???

Here are some specs from the manual.
From the next part I understand that the requirements are 20 AMPS




The duty cycle is very light 2 min on and 8 min off

Some people have wired this with 20 amp breakers others 30 amp, clearly indicating that the 50 amp outlet is only for the welder.

Does this really need #6 wire and a 50 amp breaker?

I'm really curious to get some feed back on this.

Thanks

Elliot

 

You need a 50 amp outlet as shown as well as a 50 amp breaker AFAIK.

What cord is on there now? My boss has short cords on his welders and uses 10 gauge extension cords.


A qualified electrician can install either of the
following UL-listed, 3 wire cords as a replacement
cord for this welder:
12 AWG up to 6 feet
long,
10 AWG up to 75 feet
long, or
6 AWG up to 175 feet
long



http://manuals.harborfreight.com/man...8999/68885.pdf

 

It does say this though at the end of the instructions.. And my boss often welds from his generator which is a 30 amp 240 outlet



Power Cord:
Plug the Power Cord into a properly grounded 240
VAC (at least 30 amp rating) outlet with
delayed action type circuit breaker or fuses

 

Power Cord:
Plug the Power Cord into a properly grounded 240
VAC (at least 30 amp rating) outlet with
delayed action type circuit breaker or fuses

If they say the above, do you have any ideas on why they put a 50 amp plug on it?

 

Made for use in a commercial setting where that receptacle is common for welders.

As Furd said in a residential setting using a feed that does not match the receptacle can be confusing to someone who may later go to use it so my suggestion would be to install a 6-30 receptacle using 10-2 but do not change the plug on the welder if it is a molded plug. Instead make an adapter using a foot of SOW cord with a 6-30 plug and a 6-50r female end cap.

My reason for an adapter instead of changing the plug is molded plugs seem to hold up better then add on plugs and the welder could always be used on a circuit with a 50 amp receptacle if needed. As to wiring #10 is cheaper and easier to work with.

Code note: If cable is used to supply the receptacle the white must be remarked black, red or any color but (white), green, or gray. You can use bands of colored tape on each end, felt tip marker, or liquid insulation in the proper color.

 

Based on all the suggestions I'm going to use 10-2 wire with a 30 amp breaker. Thanks also for the adapter idea. However the welder manual also not to use any extensions - so I'm still thinking about putting in the 50 amp outlet and clearly marking it as a 30 amp Welder circuit.

Thanks again to everyone.

 

The adapter is not really an extension. They are referring to long cord where length can cause voltage drop. A one foot or less #10 cord will not cause a significant voltage drop.