View Full Version : Checking myself before I wreck myself... 220v wiring.

03-17-2013, 08:45 PM
So a sub panel is the right way to do this... But that ain't gonna happen for a while with a new baby and other house priorities.

I want to tap into the dryer's 220v outlet and run an extension cord into the garage, about a 5 foot run to get into the garage.

I had a 25' 10/3 wire laying around so I thought I would wire up an extension cord for the welder that I have. 220v Lincoln 175t if it matters.

I just want to make sure my electric is up to snuff.

My welder is a 3 prong plug and my dryer is a 4 slot outlet.

If my memory serves me correctly, I will wire up one end of my extension cord with all three wires Blk (hot) Wht (hot) and Green to the ground.

On the other end of the extension cord I will wire up 3 of the 4 slots, both hots and the ground but the nuetral slot will remain unused on the end of the extension cord.

Nuetral in this application would just be there to run any 120v aspect of an appliance right? Like a light or a clock?

Fwiw, I am not wanting to burn in huge slabs of steel at this point in my life but I have a few light projects I'd like to get after. My welder is a 30amp machine. The outlet is on a 30 amp circuit.

Thanks in advance.

03-17-2013, 09:22 PM
I believe you're correct, Drew. The 3-prong plug is two hots and a ground, and the 4-prong plug adds in the neutral. I'm no electrician though, but come stare at my panels any time..

03-18-2013, 08:00 AM
Is the welder's plug hot-hot-ground or hot-hot-neutral? If it's an actual NEMA10-30P there is no separate ground, but I doubt that is the case with the welder. It's not a NEMA6-30P by chance? Is the 3rd prong round or a crow's foot ('L' shaped)? NEMA10-30 was dropped from the NEC after 1996 but is still used on appliances. So no new work can be done with it but they still build stoves and dryers that use it. The difference is the third prong being a shared neutral & ground means you can supply 125V circuits where a 250V-only NEMA6-30 cannot.

I think from your descriptions that you'll want to use the two hots and the ground terminal on the 4-prong but don't assume that is the case. You'll open GFCIs potentially if the 3rd prong is supposed to be neutral and not ground. Not to mention the shock risk of putting current on the ground unintentionally.

FWIW, you should not use a white wire as a hot leg, but in an extension no one will really know (I'd personally tag it 'cause I'd forget why I wired it wrong). Black, red and blue are hot colors, white is neutral and green or bare is ground. The odd ball exception to this is NEMA10-30, but that's really more of a missing ground because the white is carrying current like you'd expect.

03-18-2013, 01:55 PM
Thanks Dave, I'll check and get back to you.

03-18-2013, 02:09 PM
is this only to use when the dryer is not "in use". if you are not using that circuit, kill it at the sub, and run new exterior grade 220v plug externally. just a thought.

03-18-2013, 09:19 PM
Correct, unplug the dryer plug in the welder.