Tripping one leg of a 240v circuit

[DaveO]

I run the 210EXT on the 240v 30a dryer circuit, and I keep tripping a breaker. When I turn the machine on it runs for a few seconds, quits, and will sometimes run for a few more seconds, then stop permanently. This happens when just starting the machine, there is no weld load.

I use a DIY extension cord with a dryer plug for the wall and a NEMA 6-50 receptacle for the machine. I rebuilt it today to make sure there are no short circuits; some time back I had an electrician to the house for another reason, and he okayed the extension cord. I've used this extension cord on this circuit for a couple years now, with both the MIG and TIG welders, with no problems before this.

The breaker itself looks like two 120v circuits with a "join" between the switch ends. I had someone stand near the breaker panel and when I turned the machine on, they heard a click at the panel, which I'm guessing to be that leg tripping: the breaker itself is still in the "on" position, but I'm also guessing the force of one leg tripping does it not enough to trip both legs of the circuit. When I put a voltmeter on the receptacle at the wall and on my extension cord, one leg is 120v and the other is zero.

The fuse panel may be original to the house (80s). Is an older circuit breaker more susceptible to tripping? Or is there another problem to solve? Looking for some troubleshooting tips- thanks!

[Blaster]

220 (2-pole) breakers "look" like Two single pole breakers but are not. Do you have a, proper, 2-pole breaker in there or has someone taken 2 single pole breakers and maybe connected them together?

In any case, I'd be tempted to just replace the breaker itself and go from there (especially if there's any chance that breaker is 30yrs old)...

[Rambozo]

If a two pole breaker isn't tripping both poles, for sure it is time for a new one. I'd be willing to bet that will take care of it. Do you have an ampmeter? Do you run a dryer on that circuit when not welding?

[DaveO]

I checked, it is a two-pole breaker. Yes, we run the dryer on this circuit; no, don't have an ampmeter. I've been looking into replacing the breaker, trying to find a compatible replacement.

[performance]

It should be pretty easy unless you have an offbeat panel box. What brand is your breaker/box?

[zoama]

I checked, it is a two-pole breaker. Yes, we run the dryer on this circuit; no, don't have an ampmeter. I've been looking into replacing the breaker, trying to find a compatible replacement.

Just yank it out and take it to the store with you to match one up. Be sure the buss bar is in good shape and not burned where the breaker goes.

[everlastsupport]

About a year ago, 30+ year old 50 amp breaker went on me. Replaced it and all good. The buss had some arcing on it, but was OK. So make sure to check the buss too.

[DaveO]

The panel is Crouse Hinds, which was bought by Murray. The reading I've done suggests a future inspector might not approve mixed brands inside a panel so I was looking specifically for Murray, which is all over the Home Deep website but not in the store. So I'm planning to source one online. I thought about the yank-and-match method, but didn't want to leave exposed wires with young ones running around, and snapping the main off while I was out of the house would be a source of grief, so I'm reluctantly waiting for shipping.

[zoama]

The panel is Crouse Hinds, which was bought by Murray. The reading I've done suggests a future inspector might not approve mixed brands inside a panel so I was looking specifically for Murray, which is all over the Home Deep website but not in the store. So I'm planning to source one online. I thought about the yank-and-match method, but didn't want to leave exposed wires with young ones running around, and snapping the main off while I was out of the house would be a source of grief, so I'm reluctantly waiting for shipping.

Did you pull the breaker to check the buss ?

[Blaster]

If you look on the side of the breaker (CrouseHines/Murry/Bryant/GE they're very much the same and usually it says "Common Trip" on there). If you have one side tripping Alone, I'd think it's a pretty good indication something inside is Bad...

[Kevin Caron]

You might have a loose screw on one side of the breaker..

Where the two wires connect to the breaker, turn off the breaker and make sure the machine or dryer will not work.

Then take a screw driver and loosen and re-tighten both screws.

May help...

[DaveO]

Did you pull the breaker to check the buss ?

I have not even pulled the cover yet. Am I checking the buss for connectivity, or arc damage, or anything specific?

[zoama]

I have not even pulled the cover yet. Am I checking the buss for connectivity, or arc damage, or anything specific?

Just be sure it's not burned. I had to replace my panel about eight years ago because the buss burned under my A/C breaker on one phase... same brand as yours.

[Brian Ski]

Your on the right track. Replace the breaker with a compatible one. I have never heard of a inspector complaining about the brands not being the same in the box.

Pretty sure that is the problem, if not that breaker does not sound like it is working correctly anyway.

[Rambozo]

The panel is Crouse Hinds, which was bought by Murray. The reading I've done suggests a future inspector might not approve mixed brands inside a panel so I was looking specifically for Murray, which is all over the Home Deep website but not in the store. So I'm planning to source one online. I thought about the yank-and-match method, but didn't want to leave exposed wires with young ones running around, and snapping the main off while I was out of the house would be a source of grief, so I'm reluctantly waiting for shipping.

Crouse Hinds was purchased by Murray, and then Murray was purchased by Siemens! You can get a UL "Classified" breaker that is listed to work with that panel or you must use a breaker that is listed by the manufacturer to be 100% legit. It's a goofy system because the manufacturers are responsible for the testing and of course only test their own products. So even though they are identical, you can't use a Siemens breaker in a Murry panel and pass inspection, even though they might be made in the same assemble line. It's just the way it is.
That 210 EXT is listed as 31 amps max inrush, so it's most likely that is just an old weak breaker and it pops when the machine first charges the capacitors when you turn it on. The fact that the breaker doesn't trip both poles when it pops means it's bad for sure and not safe, since it leaves one leg hot. Make sure the one you ordered matches up to the old one, as you can't always trust someone else to get the right part in the box. As everyone mentioned, inspect everything and make sure the bus bars are good, and there might be some grease pre-applied to the contacts on the new breaker. If by chance you have aluminum wire, you will also need to apply antioxidant paste to the wires before you put them in the new breaker.

[DaveO]

Gotcha, thanks for that validation. I tried to pull a part number from the breaker, and got a "type MP" marking; the pattern in their naming structure runs MP "nXX" where n is the number of poles and XX is the amperage capacity of the breaker. So I'm confident I'll get the exact match. Pretty sure it's >not< aluminum wiring but I'll keep an eye out for it. Thanks for the heads up!

[DaveO]

Update: I went to order the breaker, and it turns out the Home Deep website lists Murray breakers but the photo is of a Siemens breaker. (Murray bought Crouse Hinds, Siemens bought Murray.) So I bought the breaker at the local HD and installed it. Working as expected, and I used the 210 EXT to weld on 240 this afternoon.

Thanks to all for the help!

[Rambozo]

Update: I went to order the breaker, and it turns out the Home Deep website lists Murray breakers but the photo is of a Siemens breaker. (Murray bought Crouse Hinds, Siemens bought Murray.) So I bought the breaker at the local HD and installed it. Working as expected, and I used the 210 EXT to weld on 240 this afternoon.

Thanks to all for the help!

Glad to hear you got it all sorted. Might be a good time to give your other breakers a quick once over. At least flip them off and on and see that the spring pressures feel about the same and there is nothing unusual.

[everlastsupport]

Was the buss OK. I know a welder can arc on a bad breaker.

[DaveO]

Was the buss OK. I know a welder can arc on a bad breaker.

The bus had some arc burns on it, so I cleaned it up with sandpaper down to clean metal. The new breaker had a good firm pinch onto the bus. I snapped the other breakers on and off and they felt normal.