Who welds with a GFCI?

[mrwilliamsburg33]

I have a situation where I'd just like to have others fill me in on their experiences. So... who welds with a GFCI and what do you think about it? If you had problems, did you ditch the GFCI or figure out why it was tripping?

 

[onetonbb74]

mine is a gfci, don't really know if its legit or not, mainly because my house is so old there all 20 amp 2 prongs and i bet money its just spliced off of the 20amp for the washing machine with a nice looking gfci recepticle. My welder doesn't trip it which is a good thing.

 

[shady]

some will trip one and some will not. If its in a garage and 120v I assume, then Id put a regular outlet in it and use a short gfci adapter plug when useing other tools. They will still work without a ground. they sense an imbalance in current between the line and nuetral if something happens.

 

[mrwilliamsburg33]

Yea, I know about them how how they work... I'm not looking at putting one in personally... We've got some special situations at work where all 480v welders have to be on a GFCI for personnel protection... They keep tripping... some do, some don't... it's been pretty irregular. We just implemented the system because the client required it and are in the process of troubleshooting. I was just wanting to bounce it off you guys to see what experience, if any, you've had with them.

 

[fallout232]

How old is the GFCI Equipment? GFCI's like everything else wear over time. I used to work part time with an Industrial Electrician,
We had several problems out of 3 Phase GFCI circuits.

Most common indicator of a worn GFCI is tripping for no detectable reason. They become more sensitive to the Imbalance through use and abuse and their trip points become unpredictable. If the electrical components are old I would bet that may be a factor in your problems.

Or your welding equipment has issues (Not to hard to develop a fault in something like a welder) which you normally wouldnt cause a problem in an unprotected circuit.

 

[mrwilliamsburg33]

Brand new GFCI's (implementing the system currently) and most welders are new as well as the leads. We are starting from scratch more or less. We don't have the GFCI's hard wired into anything; they have plugs to make them able to be moved from outlet to outlet (since the welders move around).

 

[fallout232]

If the problem is not in your Receptacles or welders which would be simple to remedy then the other major culprit could be the way the transformers have been wired to achieve 3 phase power. Certain configurations do not lend kindly to GFCI circuits, Particularly how the ground is setup. Im afraid that Its hard to troubleshoot distribution problems not being present in person.

Wish I could be of more help

 

[mrwilliamsburg33]

We've got a 480v Delta construction substation that feeds the site right now. All of our welders are running on the 480v lines and our GFCI's are manufactured to work with the setup.

What kind of electrical background do you have so I know who I'm talking to... lol. Electrician?

 

[fallout232]

We've got a 480v Delta construction substation that feeds the site right now. All of our welders are running on the 480v lines and our GFCI's are manufactured to work with the setup.

What kind of electrical background do you have so I know who I'm talking to... lol. Electrician?

I am no expert by any means and have limited Experience

I worked 2 years part time residential and 3 years part/full time under a Master Electrician at multi facility Manufacturing Plant. Was just shy of getting my Journeymans. 70 percent of what we did was working on and trouble shooting Large Drive and Motor systems.

I was working two full time jobs with another being my primary.
When the economy took a downturn so did my extra job. Never realized that working almost everyday for several years can do to you. Got bored with all the free time so I now dump thousands of dollars and hours into my vehicles. At least I had money before .

Take what I say with a grain of salt, I know enough to give you some leads to chase down but other than that I am as said no Expert and it has been close to 4 years now since I was laid off.

 

[mrwilliamsburg33]

Okay, thats cool. I was just wondering I appreciate the thoughts. There are many opinions and I'm just weeding through them right now. It's been kind of strange.

 

[shady]

try to see if its certain machines or certain plugs that do it more. if so I would check all connections again. a loose connection can cause a phase imbalance and trip a gfi. also the transformer setups that have problems are useually the type with whats called a wild leg. One phase will be 277 to ground and the other 2 will each be 240 to ground. which also causes a current imbalance that the gfci may see.


Ive been an industrial electrician for 14 years and unfortunetly havent had to mess with gfci's on 480 plugs before. but we use them in motor circuits all the time. probably a difference but thats my ideas on where to start.

 

[Fordum]

Like he said, see if it is certain machines or certain sockets. If it is certain sockets, then obviously check the wiring and maybe swap sockets.
GFCIs can be flaky right out of the box just like anything else.

If its the machine, grab an ohmmeter first and check for any leakage to ground. You might have to get a megger.
If you have leakage, you need to run it down.

Then, before you reinvent the wheel, go to the machine maker's website and look for info, or send an E-Mail.
Not only are you not the first outfit to try to run a welder on those, the folks who make the machines are very motivated, and have probably spent a lot more time and money finding out how to do that then you want to have to.

If their machine will not do it, you can bet some of their competition's machines will, and they have to solve that problem if they want to do business.

 

[mrwilliamsburg33]

Yea, I've been checking every trip the past week and taking notes to find similarities. We don't have a wild leg setup... and the trips have been inconsistent (as far as I can tell right now). The most common trip is on a Miller XMT 304 after the welders have put down a few beads. They break their arc, get ready for the next weld, and then notice they have nothing. Thats been the strange part.

I did talk to Miller... several different departments. Each machine has its own group of engineering and design. One guy told me that its like a lot of separate companies within Miller. I didn't know that.

Anyways, thanks for the ideas. I do plan on taking a meter out to the machines that trip to measure the resistance between the ground clamps and the steel its clamped to. I have to have some leakage somewhere... so its just a matter of tracking it down.

 

[Fordum]

Didn't know that about Miller either.
Here are a couple of measurements I would make.
First, I would check between the ground clamp and the electrical ground with the machine on but no welding.
To do that, I would first check it with the meter set on voltage, not ohms, in case there is a voltage difference so as not to blow the meter.
If there is a voltage difference, check it with the machine unplugged, meter set on ohms.
I know some machines do not tie the welding ground to the earth ground. Some do.
Check your results against a machine that is not giving problems. If the two grounds are tied together, it may just be a loose ground connection inside the machine.

Here is something you might not have thought of.
Try to find out what they were welding when it tripped, and how it was laying and on what.
Its possible that the welded piece was touching something grounded and moved on or off it.

I fixed a weird situation for a friend many years ago. He had a lot of pigs on his farm, and also did a lot of repair work.
He called and said that he would be welding in his shop, and often it would go fine for a long time.
Other times, he would just get started welding, and had to stop and go round up the pigs that were wandering everywhere.
The fuse in his electric fence charger was blown.
He tried a new charger, but that one would blow too.

He finally realized that while it did not happen every time, he was welding every time the fuse blew. It never blew except when he was welding.

He had asked a couple of electricians to check, but they did not know what was wrong.
I rode over. Fence charger was working fine. I picked up a piece of steel, put it on a bench, and did some welding.
Went fine.
I asked what he was welding the last time it blew.
He took the welder and jumped an arc to a Ford 9 inch sitting on the ground he had been welding on the spring perch.
I heard the fuse blow from across the room.
Checked, and it was not blown, it was vaporized inside.
Changed it, and went checking.

Every electric fence must have a good earth ground to work, since it shocks the pig from the wire to the dirt he is standing on.
His ground was outside the barn in a wet place.
It was a good ground.
Then I checked the earth ground for the meter base to the barn.
Good ground rod, good wire, so-so clamp. About 75 feet between the two.
I silver soldered the ground wire to the rod eliminating the stupid clamp.
Then, I ran a nice heavy wire from that ground to the ground on the fence charger.

That cured it.
Problem was a split ground. When he was welding on a table, all was well. But when he welded something touching the ground, it went to the closest ground, which was the fence charger.
By tying the grounds together, they were the same potential.

 

[mrwilliamsburg33]

I haven't gotten the meter out and starting going through that yet... but everyone has basically been welding mild steel... mostly hangers or supports to the building structure. They have their ground clamp within inches of the bead most of the time. Thr ground grid here is superb... everything is grounded to keep the potential the same. There will be a lot of instrumentation in these building so they made sure not to have any stray voltage floating around.

If I didn't mention before, the welders that seem to be tripping are mostly the same model. We've got 2 or 3 models on site (40+ total units I believe) and the Miller XMT 304 seems to be the most problematic one. I haven't talked to the Miller group specifically about that one or looked in to it a lot but I'd like to know what that one seems to be the one with most the problems.