NO. Probably you are adding a cooling fan to the welder. The 240 welder has no neutral, only an equipment ground. The NEC forbids the use of an equipment ground for a neutral. Apart from the code, it is potentially extremely dangerous to do so. Your welder would need a 4 conductor supply cord and the circuit would need a neutral. If a 240 to 120 transformer was installed in the welder, the neutral would not be needed. Or find a 240 volt fan (or whatever).

No.

You cannot use the grounding conductor (safety ground) as a part of a circuit.

Change to a 4-wire plug since your load is no 120/240 V and NOT a straight 240 V load.

The special exception for ranges and dryers (only) was removed many code revisions ago, and is only allowed for 'grandfathered' installations.

It was never allowed for welders.

Thanks for your inputs....

Please be patient with my dumb questions....

You say that it has been allowed for ranges in the past, so it seems that it cannot be too bad a thing. Why did they change the code?

My 240 volt welder outlet is about 6 feet from the breaker box. In that breaker box the 'equipment ground' from the welder outlet is connected to the same place that a neutral wire from a 4-wire outlet would be connected. So, if I use the 'equipmnet ground' as a 'neutral' 6 feet away it seems that it would be electrically the same....

Having said that, just what is the 'hazzard' in using a 120 leg and 'equipment ground' for 120 volts. How will I be compromising safety? Why is it 'potentially extremely dangerous to do so'?

The only difference with a 4-wire connection is that I would be paralleling the green equipment ground with a white wire...

BTW, my home and hookups are circa 1970.

I gave you a good correct answer. Accept it or reject it. At the link is one explanation, perhaps not the best. Do some research on your own for further education.

Here is a link that might be useful: Link

"You say that it has been allowed for ranges in the past, so it seems that it cannot be too bad a thing. Why did they change the code? "

I had become an ever increasing safety hazard, especially with all the ranges that are actually 120/240 V loads.

Some new ranges with electronics would not even operate with a three wire setup.

You are only six feet from the panel so it will be really cheap and easy to do a 4-wire circuit. Alternatively, you could add a 120V input to your welder to run the loads that require it.

What Brickeye wrote was correct, but confusing to a DIYer.
The range/dryer thing for 120/240v circuits has NOTHING to do with your straight 240v welder circuit.

The fact that the grounds and neutrals are connected to the same place in the main panel is MEANINGLESS. It's what they do, and their intended role outside the panel that matters. It's like saying drinking water and toilet water wind up in the same place so they both must do the same thing.

You 100% CANNOT, AT ALL use an equipment ground for the neutral of a 120v circuit. Is it done by hacks who don't care, sure. Is it unsafe, YES.

BTW: is this panel the main panel for the house or a subpanel in the garage?

Weedmeister,

It is a Sub Panel in a detached garage....fed from a 60 amp breaker in the main house panel.

Thanks for all of your inputs. I get the message:

....'NO!'
....'You 100% CANNOT, AT ALL use an equipment ground for the neutral of a 120v circuit.'

However, that still did not answer my question:

"How will I be compromising safety? Why is it 'potentially extremely dangerous to do so'?"

But, after a little thought, I can see a case where that hookup could be very dangerous. I will share my example just in case someone else has the same question in the future.

Here is my imagined case:

In a correctly wired 4-wire 220 volt system it is permissible to wire 120 circuits in the equipment as long as the return is via the neutral (white) wire. In this case you can imagine any one or any combination of the four wires becoming open. No matter which are open, there is no immediate danger, without at least some other fault in the machine. No dangerous single point of failure.

In a 220 volt machine wired with 3-wires there is also no single point of failure. Any combination of the three wires can be open without 'immediate' danger. Again, no dangerous single point of failure.

If, in the 220 volt machine wired with 3-wires, one wires a 120 volt circuit with the equipment ground as a return there is a potentially a big problem. If the equipment ground becomes open on its path back to the panel box, then the only path for the return current to flow in the 120 volt circuit is to the case and then through anything or any person that gets it to earth ground. That is hazardous!

Yes you are compromising safety. The equipment ground is for safety and must be a low impedance path to ground. It is designed to carry NO CURRENT in a normal situation. Doing so jeopardizes it's whole role in safety.

It's got SQUAT to do with something potentially opening.

"It's got SQUAT to do with something potentially opening."

??????

You obviously did not understand my example. My example gave just one possible reason WHY the ground "is designed to carry NO CURRENT in a normal situation."

Sometimes a simple example helps to convey the REASON for the 'rules' and 'codes' and why not following them can be unsafe....

If you want to add a fan, just use a 230v fan instead of trying to reinvent the wheel.

I've ordered from Drill Spot once when I needed a fuse I couldn't find locally. I paid an extra $2 for "priority" shipping and the fuse was delivered that afternoon. Damned good service but there's a local Grainger branch (Drill Spot seems to work with Grainger)

Here is a link that might be useful: 230v Axial Fans

The grounding conductor shall not carry current under normal conditions because people who know a hell of a lot more about electrical safety than most of us DIYers determined that is the proper and safest way. So we cannot precisely answer "why" safety would be compromised. Using the grounding conductor as a neutral would work. It might work OK that way forever. But it's also improper and a code violation. Don't take a chance.

In the range example, it was the neutral that was allowed to serve as the ground, not the other way around. Some old electric ranges also had a built-in 120V convenience receptacle and an electric clock/timer.

"Sometimes a simple example helps to convey the REASON for the 'rules' and 'codes' and why not following them can be unsafe....

Do you want to know " the REASON" for every law. rule, and regulation?

While it can be a nice mental exercise if you are intimately involved in the design of wiring and equipment.

It is not all that useful for the average person interesting in hooking something up correctly and safely.

Grounds (grounding) conductors are not current carrying parts of ANY normal circuit.

And screwing around with the welder may (depending on the rest of the house wiring) screw up the grounds on any circuits that get aggregated together in a subpanel, etc...

The low impedance path does TWO things....it makes sure the breaker opens quickly in the case of a fault, and it keeps the potential of exposed conductive parts of various equipments at a safe level that prevents dangerous currents from flowing to a better ground.

If you want to know the reasons for everything, go down to the local community college and start taking your electrical licensing exam. We have a whole semester course on BONDING AND GROUNDING.