Welder outlet metal plate carries current

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Old 02-14-20, 01:43 PM
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Welder outlet metal plate carries current

Had some issue with my welder not wanting to weld that well. Anyway, today, when unplugging the power cord, I touched the metal faceplate and got a nice zap. Obviously this is not ideal.

This is in a barn wired 15 years ago. This has 3 4ga or 6ga wires going to the shop. This is precisely why we don't do it like this anymore. Again, this is a THREE WIRE RUN. Anyway, I need some help testing some stuff with my good multimeter and see if I can figure out what in the hell is going on.

First, I need to verify my wiring on my NEMA 6-50 plug with my multimeter, but I have never used it for testing 220V. It's possible the ground and hots are wrong....How do I test this?

Second, I need to use the same meter to test and figure out why in the hell my metallic faceplate is energized.

Can I get some assistance? Yall have been amazing with my electrical endeavors in the past....just need a little guidance here.
 
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Old 02-14-20, 01:57 PM
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FIRST PROBLEM:

The electrician that ran the wire to the welder used 3 black wires. He mislabeled them. So, I have continuity between what is SUPPOSED to be one leg of the HOT and ground. This means at a minimum, the ground and one leg of the hot were flipped in my welder outlet. Yikes. And not a single breaker tripped. EEEEkkkkk.
 
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Old 02-14-20, 02:38 PM
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When you measure voltage do you have 240 volts between any pair of wires?
 
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Old 02-14-20, 03:41 PM
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It wouldn't weld correctly because the welder was only getting 120v.
A breaker wouldn't trip as there is no short.

You were lucky..... because not only was the plate hot...... the entire welder was hot.

Make sure when you rewire the receptacle that you have 240v in the correct location.
The middle pin is ground.
 
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Old 02-14-20, 04:22 PM
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Iíve been fooling with the welder and plate for weeks. Itís never once shocked me. Iíve almost always had my steel toe electrical hazard rated boots on so maybe I just never got a decent ground on me to fee it. even when I got a zap today it was nothing like I would expect a full zap to be.

My welder plug looks like a giant 110 v plug. The two blades each get a hot and the rounded horseshoe looking one is ground. With my meter set tO volts, how do I use it to measure a full 240?

I feel like I should put the black and red probes into both blade slots at the same time to see if I get 220v but Iím having a bran fart and I want to run it by yíall first.
 
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Old 02-14-20, 04:29 PM
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Meter should be set to the next scale over 240vAC. If it's digital.... it should be automatic on ACV mode.
Then you measure the two slots. You should get 240v there and 120v from each one to ground.
 
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Old 02-14-20, 06:30 PM
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I have a Klein MM1000. As long as its set to AC, it's auto adjusting. I'll test this out when I swap those wires.
 
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Old 02-14-20, 10:12 PM
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The electrician that ran the wire to the welder used 3 black wires.
FYI, this isn't allowed by NEC (except for 4awg or larger). Grounding wire must be green or bare.
 
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Old 02-15-20, 04:24 AM
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It might be 4 gauge.

Do you know why they donít allow this? I bet this thread is why. Lol.

Ill have to be sure to properly relabel the wires. Thatís the only option I have at this point.
 
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Old 02-15-20, 04:38 AM
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agdodge4x4:
My welder plug looks like a giant 110 v plug. The two blades each get a hot and the rounded horseshoe looking one is ground. With my meter set tO volts, how do I use it to measure a full 240?
agdodge4x4 take a quick look at this chart

NEMA Straight Blade Reference Chart

It may help you identify which plug you have on your welder. Also, many times the NEMA type is stamped right on the end of the plug. Also for future reference to.
 
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Old 02-16-20, 07:29 AM
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Unplug the welder. Set your meter to ohms or resistance or continuity.

Flip the switch on the welder to on.

Measure between the ground plug pin and each of the others, in turn.
In both cases you should get infinite ohms or resistance, or no continuity. Otherwise you have a defect or miswired connections.

Next, set the meter to AC volts, greater or equal to 250 volts if voltage ranges are designated. Yes, you need to stick the meter probes into the receptacle, any two prong holes at a time. Best done of you are standing on dry cardboard and you can get things to stay in place so you can do the test with one hand in a (pants) pocket.

Was the receptacle in question repaired or installed or rewired recently?

Do not measure resistance or ohms or continuity with power applied to the subject being tested.
 
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Old 02-18-20, 07:51 PM
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I verified that what I found was correct. The issue here was nothing more than a swap of a hot leg and the ground terminal made possible due to the fact that the ground was not jacketed in green or bare. I found this by testing for continuity at the panel and my outlet and with grounding system. The welder fan now sounds like it should when powered on from the outlet. I have not tested welder operation but I suspect it will work noticeably better. Thanks for the guidance.

 
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