I've moved all my big welders into a leased shop and I needed something to tinker with at home. I picked up this today (17 March, '03) and I figured this was the perfect opportunity to do a write-up on making a conversion/extension cord because I've seen this question asked many times.
There's nothing like a new welder to bring out the kid in you!
This is a standard 230v plug that came on my machine, but I don't have any wall plugs like this anywhere in my house. The only 230v plugs I have are for my stove and for the dryer in the garage (the obvious choice).
This is the wall plug that my dryer plugs into. The first thing you should notice (aside from crappy resolution) is that it doesn't match the plug on my welding machine. I don't want to cut the plug end off my welder so I need to build a conversion cord. Before I start building a conversion cord I need to make sure this 30 amp plug will provide adequate power for my welder.
I first needed to determine if my plug provides 208 or 230 volts, as this will make a difference in the amperage draw. @241 volts my amperage draw should be safe but I checked the data-plate to make sure.
As you can see, @230 volts the machine will draw 27 amps at its highest setting. @240 volts (what my meter showed above) its even less so I now know for sure that the 30 amp dryer plug will provide adequate power for my welder.
My next step was a trip to Lowe's. I picked up a female plug end ($9.91) to match my welding machine and a male plug end ($8.91) to match my wall plug (you will need to swap out the center "|" shaped common lug with the provided "L" shaped common lug). I also picked up 20 feet of 6/3 wire ($17.00) with ground. I could have gotten by with smaller wire but I decided to over-do it because although this is only powering a welder today, there's just no telling what I'll do with it tomorrow. Total cost at Lowe's was $38.33 (tax included).
The ground wire is useless for this application so I cut it off flush with the end of the stripped outer jacket. The red and black wires will both be hot and the white wire will serve as ground.
Here are the plug ends wired into the cord. It really doesn't matter which side you connect the red or black to, and it doesn't have to be on the same side on each end. Just make certain you don't hook either of them up to the center prong (the results will be tragic if you screw that one up!). For uniformity I've hooked them up left to right, red-white-black.
After everything is snugged down good, I have a 20ft. conversion/extension cord ready to power my welder.
As with every job, it always goes smoother when you have the right helper! :-)
Nathan W. Collier
AWS D1.1/D1.5 Certified Welder
Disclaimer: Do not try this at home.