15-50 plug

[kellymc]

I volunteer at a local high school for a robotics club. We have a 3 phase 15-50 plug in the room that we would like to re-purpose for our 220 welder. What is the proper way to go about making the change? Can we just make an extension cord to plug into the 15-50 socket and only connect across two of the poles for the 220?

Kelly

 

[theoldwizard1]

am not an electrician, but the answer to your question depends if it is a delta (Δ) or why (Y) 3 phase transformer upstream.

In one case you will get 220V, the other case 208V. Check the welder, either may be okay.

 

[Speedy Petey]

If this is in a school DO NOT TOUCH IT.
Contact the maintenance dept and ask them. Most likely you'll have to bring in an electrician.

I do like your idea of an extension/adapter cord. Just make it up with the proper 15-50P on the plug end and a 6-50 female on the other end.
This way you can use the existing receptacle and not mess with it at all.

 

[Speedy Petey]

In one case you will get 220V, the other case 208V. Check the welder, either may be okay.

It would either be 240V or 208V. "220v" is pretty much non-existent in the US these days.

 

[theoldwizard1]

It would either be 240V or 208V. "220v" is pretty much non-existent in the US these days.

My bad. I still intermix 220 and 240.

 

[Speedy Petey]

My bad. I still intermix 220 and 240.

As do most people.
I have seen 208V systems on the high side, like upwards of 215V. To some this may look like a 220v systems.