1

It seems really easy to find the opposite (how to plug a 4 prong plug into a 3 hole outlet) but I actually need the reverse (I need to plug a 3 prong plug into a 4 hole outlet) and not sure if it even exists.

I have this welder: https://www.harborfreight.com/stick-225-inverter-welder-with-electrode-holder-64978.html

...which includes a 240, 3 prong plug. It's the kind that looks like your standard plug (two parallel prongs and a ground). It's not the kind dryers use where you have 3 angled prongs.

On the wall-side, I have a 40amp, 4-wire outlet (2 hot, neutral, ground).

Is there a way to use this welder with this outlet? If so, is there an off-the-shelf adapter for this? If not, could I wire up my own using a 4 prong plug wired into a box with a 3 prong outlet. If I can do the latter, what's the proper way to do that?

DA01
  • 24,586
  • 30
  • 82
  • 153

1 Answers1

2

The simple solution (unless you drag it to other places with different receptacles) is to put the appropriate 4-prong plug on the cord, with the neutral prong of the plug not connected.

Another option is to add a box next to your box with the 4-prong receptacle and install the correct 3 prong receptacle in it. If you plug in and operate two things at once you may trip the breaker, but it spares you the "extra cord and plug" that your self-made adapter would have.

Edit to add: If you don't actually have something that uses the 4-prong receptacle, you could just replace the receptacle (capping the neutral wire in the box) and (if you are nice) write a note on the wall that there is a neutral available if someone wants to change the receptacle back to 4-prong later.

Ecnerwal
  • 235,314
  • 11
  • 293
  • 637