220volt outlets and the stubborn arc welder.

Old 08-28-04, 12:20 AM
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220volt outlets and the stubborn arc welder.

hey guys.

about 2yrs ago i moved in my old grandparent's house, my grandfather was a diy fanactic and made several additions to house's electrical system [not sure if he did the 240v outlet work, or not] and at some point he had an arc welder. In the garage there are 2 different 240v outlets. the arc welder checked out along time ago, but recently i purchased a small, cheap arc welder and would like to learn the magical art of welding. however the 240v plug on the arc welder doesn't match up with any the existing plugs in the garage. one of the outlets looks like one you would see for an electric clothes dryer/oven range combo, and the other i have no idea. i have also included 3 images in the post; 2 pics of the 240v outlets, and the plug of the new arc welder.

there are a few additional notes, i need to include:
1) i haven't checked the 240v lines with a voltmeter yet, i have one that can measure 240v, but haven't gotten around to actually measuring it yet. so the outlets might or might not be usable.

2) i have a federal pacific fuse box in the house, with a bunch of a additonal cb boxes wired on the sides. i had a furnace and condensor installed back in feburary/march and the installer had suggested i get it rewired with current manufactor, since, the wiring in the box is a rat's nest, and cb are hard to find these days. i also have no idea what cb the 240v outlets are wired too.

3) i am an electrical engineer by trade, and know all about electrical behavior, and if any house wiring needs to be done, i will of course let a professional do it.

my first question is, can i safely re-wire the 240v plug on the arc welder with one that fits the outlet?

judging by the pictures and assuming it's safe to rewire, does anyone suggest which outlet would be better for the welder?

thanks guys for any help, and if you need any additional pics, or info plz let me know.

thanks again for any help.

specs on the welder, if needed:
input:230v single phase, 60hz 22amps.
open circuit voltage: 48v
welding current: 40a-100a
duty cycle: 10%@70amps

this is one of the 2 240v outlets in my garage.

the second one:

the arc welder's plug:

Last edited by ijedi; 08-28-04 at 01:04 AM.
Old 08-28-04, 09:19 AM
Join Date: Sep 2000
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If the plug doesn't match the receptacle, it is an indication that the circuit is unsuitable for the appliance. So you either need to run a new circuit, or change both the breaker and receptacle to match (only allowed if the amperage rating of the breaker is being reduced, not increased).

The receptacles you showed look like a NEMA 10-50 (50 amp, 120/240 volt) and a NEMA 6-50 (50 amp, 250 volt). The plug is a NEMA 6-20 (20 amp, 250 volt).

It is not allowed to plug a 20-amp appliance into a 50-amp receptacle because it does not provide adequate safety protection. So you should replace the 50-amp double-pole breaker with a 20-amp double-pole breaker, and then you can replace the receptacle with one that matches your plug.

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