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Help! Electrical problem

Stuart Davenport Knives

Stuart Davenport Knives

Knifemaker / Craftsman / Service Provider
Joined
Feb 7, 2022
Messages
471
I know enough about electricity that it shocks me.

Situation: TW-90 grinder (110V) plugged into a regular, non GFCI outlet. 9 times out of 10, when I turn the grinder off, it trips the GFCI outlet on the adjacent wall. I have a wifi speaker, overhead LED shop light, and phone charger plugged into the GFCI via an electrical outlet strip. Almost every time I turn the grinder off, I have to reset that little button, and I'm over it. It used to not happen quite as often, and I thought it was happening on the more humid days. Now it is almost every time, even when humidity is extremely low. What might cause this, and how can I fix it?
 
Some GFCI outlets are super sensitive. If it were my place I would just replace it with a regular outlet.
 
You are saying a load on a non GFCI is tripping an actual GFCI outlet ?
 
GFCI sensitive, outlet strip sensitive, pulling some amperage. Everything probably on same breaker=tripping GFCI
 
If it a garage circuit, all the outlets are linked to the GFI outlet. You will need to change the GFI outlet to a regular one. This is not code, so you would have to change it back later on. The best situation is to run a line from the breaker panel to the grinder on its own breaker and anon-GFI socket. Depending on how far the breaker box is from the grinder, thus may be very easy to do.
 
I have had this problem as well. The VFD is not designed to work with the GFCI. There newer models of the same VFD have corrected the issue and they work with GFCI outlets now. But I just changed out the outlet in my garage and it fixed the issue.
 
Dang things wear out too. We've replaced three around here the last couple of years. Not a tricky job and the GFis are relatively inexpensive.
 
Good point, Dave.
Breakers and GFIs will get weaker with age and repeated tripping. I have changed a breaker more than once that repeatedly tripped for no apparent reason. It usually solved the issue.
However, what you describe is a standard garage GFI circuit. Many VFDs will not be compatible. Changing the GFI outlet for a standard non-GFI type will solve the issue.

A temporary solution and test would be to run a heavy gauge extension cord to the nearest non-GFI circuit inside the house. Use the shortest cord that will reach.
 
Stacy E. Apelt - Bladesmith said:
Good point, Dave.
Breakers and GFIs will get weaker with age and repeated tripping. I have changed a breaker more than once that repeatedly tripped for no apparent reason. It usually solved the issue.
However, what you describe is a standard garage GFI circuit. Many VFDs will not be compatible. Changing the GFI outlet for a standard non-GFI type will solve the issue.

A temporary solution and test would be to run a heavy gauge extension cord to the nearest non-GFI circuit inside the house. Use the shortest cord that will reach.
Click to expand...
Thats true on the VFDs. My garage had two separate circuits in it too. One was non GFI and the other was GFI. I lived with that quite a while knowing that I could plug in my grinders here but not there. Had a major re-wiring done along with MAJOR light up grade done and that took care of it.
 
Just changing the GFCI outlet to a standard outlet might not correct the problem. GFCI outlets can be wired to feed other outlets but I wouldn't just get rid of that protection. If it were me I would have an electrician(or diy) run a dedicated outlet for your grinder and leave the rest of the outlets be, after replacing that GFCI outlet. A dedicated outlet run from a separate breaker in conduit would be pretty quick and easy.
 
Oh wow I didn't think I would get so many replies. MANY MANY thanks to everyone who posted.

Crag, you are correct. NON GFCI is tripping the GFCI. The only load on that regular outlet is the 110V grinder. How many amps, I don't recall what that TW90 pulls.

Many of you suggested changing the GFCI to a regular outlet. I just asked my Dad, who spent his whole adult life owning and running a hardware store. I grew up in that store from an infant. I know just a little bit about a lot of hardware store stuff, but not an expert in anything by any means. He suggested the same. Change the GFCI to regular.

Funny, today turning the grinder off only tripped that other outlet, yes on same circuit, only about 50% of the time. So strange.

Mr McPherson, thank you very much. David, Stacy, all of you, THANK YOU VERY MUCH!!!!. I will try and get that done ASAP.
 
I did construction work in the early 80s and they were putting those in every new house built, kitchen and bathrooms, they were notoriously sensitive back then. After the new home was inspected and got its certificate of occupancy the home owners had the builders remove them because they simply were crap. I have them in the house I live in now and have never had a problem with them, kitchen-bathrooms- laundry. I built my shop 30 x 50 and ran a separate 100 amp service with 12 110 volt outlets and two 220s. Personally I hate gfci outlets, they have their place somewhere according to some people but I wouldn’t have them in a garage or any in my shop.
 
I think the GFI craze was fueled by the graphic depiction of hair dryers and radios falling in the bath/shower/pool/hot tub and electrocuting people used in movies. With many items now being battery powered, these dangers are not what they were in the 1940's. If a place has wet floors or you will be doing wet work, I can see a GFI. When I was a boy, wiring was done wrong a lot of times ... even by electricians. Appliances and piping were almost all made in metal. Wiring was 2-wire not 3-wire as today. The hot and common wires were often reversed, and the no-ground outlets didn't care. If that situation existed ( and often did), and you touched one of those metal appliances and the sink at the same time, you got a shock.
Today all wiring should be three wire and properly installed. Many hand held appliances are battery powered. Flooded garages and basements aren't as common as they were. GFI circuits are required by code in bathrooms, kitchens, outdoor receptacles and circuits, and garages. I tend to try and follow codes when I can, but the GFI in my garage has been nothing but a nuisance. I am remolding the garage into a full pantry and will do some cooking (sous-vide and such) there. I simply re-wired the GFI receptacle that controls the whole garage, making it only control that one receptacle. The others will not loose power if the GFI trips. I have a note in the breaker box with this info. If I ever sell the house ... or someone gets it after I die ... they can change it back if needed.

An electrician or someone familiar with GFI wiring could easily do the same for you and make the receptacle that you plug the grinder into non-GFI controlled. It is a very simple change at the GFI receptacle that takes less than 5 minutes. It entails moving the output LOAD wire (the one that goes to the other outlets) to the LINE screw where the incoming LINE hot wire is. It can also be done by cutting the HOT incoming LINE, removing the LOAD wire from the GFI, and splicing the three ends with a wire nut. Obviously, all work should be done with the power off to the circuit.
 
As a licensed master electrician, I would suggest keeping the GFCI protection if possible. If you can find a good electrician, perhaps a referral from someone you trust, maybe have them get a look at it for you. It sucks to spend money on something like that sometimes, but there are a lot of variables when it comes to troubleshoot electrical wiring, and safety is pretty dang important. I think the comment above about the VFD having GFCI compatibility issues is an interesting point. A good electrician can help identify for sure if your VFD will run on a quality GFCI or not. I guess I just wanted to say, safety first. Electricity can be dangerous in some situations, so its good to get a pro's eyes on things from time to time. Hope you get it resolved. Take care.
 
I get that GFCI outlets are often easy to trip and that bothers people but they aren't supposed to do that so easily. In my mind it suggests there is some other small issues contributing to the easy tripping. I have run 90lb jackhammers off a GFCI outlet all day with no issues and I have watched them pop with a radio before so it might be the outlet itself is poor quality or has been tripped too many times or there is a small wiring issue along that circuit. I have heard quite a few stories of issues with metal dust causing all sorts of issues and fires. There is a shop in my area that had a fire from steel dust accumulating in an outlet, when they rebuilt they took extra time and effort to identify future problems before they happen.
 
thebrain said:
I get that GFCI outlets are often easy to trip and that bothers people but they aren't supposed to do that so easily. In my mind it suggests there is some other small issues contributing to the easy tripping.
Click to expand...
VFDs just don't play well with GFCI's by their nature. It's not that there's necessarily something wrong, it's just how VFDs work.
 
Yes, the VFD creates a ripple in the AC lines. This is read as a problem by the GFI and it shuts off the power.
 
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