[Dugg]

My welder was originally installed within 3 feet of a GFI in my shop..... Ah, don't you agree shop sounds bigger and more professional than 2-car agrage?
The welder tripped the GFI's every time I stepped on the pedal. So, I've spent over a hundred dollars moving the welder to the other side of the gara... ah, I mean shop and everything was happy for a day.

Then I discovered I had the HF switched to "continous" and when I switched it to "start only", the GFI's again trip.

When I moved the thing I added a 14 ga wire from the welder frame to the conduit assuming this additional ground might help.

So, if running the HF on "continous" actually was the reason it didn't trip the GFI's, should I run it that way even for DC welding? Or, should I replace the GFI's with ordinary receptacles and live in fear of the electric code police hunting me down? .... I'll try to remember not to water down the floor and operate electric tools when barefoot.

[Al_The_Man]

What size GFI are you using for a TIG welder, is there a reason you hooked it into a GFI in the first place?
Every time you connect the work or the the 14g wire to ground, you are defeating the GFI.
unless you have 100% isolation between the supply and the output, you are causing it to trip, If you used a GFI because of a lack of adequate service ground, you could set up a ground rod, but I would use the service ground direct with a fused disconnect or a normal breaker.
Your unit should be wired with 2 wire and ground if 1phase.
Al.

[Dugg]

Sorry Al and gentlemen, I didn't do a very good job explaining my problem. The welder is not on a GFI.
The welder is powered from a 220v 50 amp breaker in a sub-panel I installed in the garage.
The welder was originally located within 5 feet of this sub-panel.
The welder used to trip a 110v GFI breaker that was fed from the main panel in the house located within 3 feet of the welder.
The welder used to also trip a second 110v GFI fed from the sub-panel.
Then I moved the welder to the other side of the garage by installing 3 each number 4 wires in 1" metal conduit from the sub-panel to the other side of the shop... (although it's still only a 2 car garage)
The new welder location is about 10 feet from the second GFI and twenty plus feet from the first GFI.
Now, it still trips both GFI's within what seems to be a few seconds which I associate with the duration of the "start only" HF used for DC welding.
When I inadvertently had the HF on the "continuos" setting, I think it was the reason the GFI's didn't trip.
So, should I leave the welder set on continuos HF? Will this hurt the welder when in DC? Or should I get rid of the GFI's?
I hope this gives a better picture of the layout and again, I apologize for my lacking first explaination.

[ViperTX]

My GFI in the garage trips ocassionally when I switch off the shop lights in the garage....so,...

[JEFFY]

I know you said your welder power is in conduit, but what about the rest of the wiring?(romex, plastic conduit,steel conduit)
When you ran the sub panel did you run a common ground to the same ground point of the main panel?(water main or ground rod) I seem to remember that a loss of a true ground can cause havic at times. You may also try a hospital grade or commerical grade of GFI if you haven't tried already tried a differant GFI. Also is there anything else being protected by the GFI or pluged into the GFI at the time it trips? Exstension cords, shop lights, drop lights and other misc shop equipment are not always shielded enought to keep out the EMI from the RFI of the hi freg. causing GFI to trip
I'm very curious about this as I'm building a new shop now and planned on the safty of GFI's, if you do find the cause or solution please post the cause.

[mxtras]

Or try GFCI breakers instead of outlets? I have no personal experience but I have read/heard they are more stable.

Scott

[ViperTX]

I've never had problems with my GFI Breakers....just the outlets that have GFI built into them.

[Dugg]

Hey Jeffy, Your post got me thinking.... yes, I do occasionally think, but I didn't inhale.
When I added the sub-panel in the garage, I piped it from the main box in plastic conduit. There are three number 4 wires and a single number 6 for the ground between the two panels. The whole project was done with a permit, inspected and signed off with no problems.
I'm beginning to think I need a better ground at the sub-panel. So, I'm going to pound one of those eight foot grounding rods onto the soil (soil? this is the mountains in Colorado, we have rock) and add a ground wire to the sub panel..... all this will be addressed next summer when the ground isn't frozen and covered with snow.
Hmmmm, maybe I can run a ground wire from that panel through the garage ceiling and attach it the water pipes for the room above.....Thanks

[Al_The_Man]

Re-thinking, Ironically a better ground might make it worse, the method GFI's use detects whether even an ungrounded piece of equipment is actually passing current to ground, as in 2 wire, double insulated power tools.
The way it is done the GFI monitors current in both conductors, live and neutral, not the ground conductor, per-se.
If equipment actually has a condition where a minute ground current is actually flowing, the current between the two conductors is unbalanced, and the GFI trips.
I suspect that the High frequency is causing a small current to pass to ground, either capacitively or inductively and causing the trip.
Al.

[samco]

I have had issues with gfi's and inductive loads. (even when they are not on the same circuit.) I just figured I needed to buy better quality ones not the 10 dollar ones from menards. (have not yet)

sam

[Mortek]

You need to try isolating the HF as much as possible. It's noise can affect electronics everywhere. Ground the sub panel as you are planning, also drive another ground rod next to the welder and ground it. run a ground wire from the soil ground at the welder to your work table. I have a welder in my garage also plus a 3axis machining center. I was welding aluminum one day (HF continuous) while running a 3d machining operation and the hf cause my work coordinate to shift in my mill. It used to send my vcr into fast forward while playing a movie. I've seen it type in characters in a computer just by waving your hand over the keyboard. I have a miller 350LX Syncrowave machine and the manual gives a diagram of how to ground the hf.

Ken

[Dugg]

Thanks Mortek,

Your suggestions will be followed next spring when the rocks aren't all frozen together and I can pound a rod into the ground. I've been kicking an idea around to build an air powered hammer that could be used to pound in these ground rods and then rent it out to contractors.... oh the heck with it, I'll beat the rod into the ground like everyone else

What is working for now, is just leaving the HF on the continuous.

Thanks all.

Doug

[thkoutsidthebox]

The first night of my welding course we were told something about the HF and essentially that you should have a seperate mains circuit coming in to run the welders off. We're finished for the christmas now and I can't remember any more details, sorry, but think it might be related to your problem. If your still wondering by January I'll find out.

[Dugg]

thk... thanks, but leaving the HF in continous mode is working and I've already gotten accustomed to it that way.
Thanks,
Doug

[tadream]

My first post on CNCZone, here. HF can do strange things. It's around 3000 volts at approx 3Mhz. I've had more than one customer whose rigs were dialing numbers on their phones(one of them to 911 repeatedly. Cops NOT happy). The best solution is usually a driven ground rod near the work table. Next step would be a .05 microfarad cap from each side of the GFI to ground. Might try that 1st in your case as its cheaper and MUCH easier than the ground rod. Hope this helps.

[millman52]

Don't know what your electric code is there on GFIs Here they only have to be on circuits within "x" feet of things like bath & kitchen fixtures.

As I understand your problem It isn't your welder but 110V outlets around your "SHOP" walls that are tripping.

If your local electric code doesn't require them in a garage. I'd just replace them with regular grounded outlets.