VFD triggers GFCI outlet

Hello! I have made really good progress hooking up my new 800W air cooled spindle. Unfortunately I’m finding that when I get to any appreciable RPM on the spindle (ie 8000rpm and above) it trips the GFCI outlet in my garage…. It’s a dedicated outlet with 15A available to it. At highest speed and torque this spindle only pulls ~6A. In the US I believe it’s code that you must have GFCI in garages since it’s a potentially “wet space”. Googling around it seems pretty common that VFDs trip GFCI outlets. Does anyone have a solution here? I am using an EMI filter at the input.

Worst case I guess I could swap the GFCI outlet for a normal one, but I’d prefer not to do that unless necessary.

I have a Jet 1221VS lathe. When I hook it up to the GFCI outlets and change speed it will pop the GFCI. I have a single outlet in the shop that is not a GFCI and it works fine.

The purpose of the GFCI is to check between all 3 legs of a 120v outlet to see if there is voltage bleeding and shuts it down. For instance a washing machine has rubber feet and isolates it from ground. So if something happens and the case of the washing machine becomes charged the GFCI shuts it down before you touch the case and shocks you. So a GFCI is an important safety measure.

That said some variable electronics trip GFCI and likely your VFD is doing that. So if you replace the outlet with a standard outlet just be aware that other things you plug into that outlet will not be protected. I understand your frustration but I think it is just the nature of the variable electronics that make it problematic with GFCI outlets.

My old neighbor would set up Christmas lights. The extension cords would run along the ground and when it rained some of them became submerged in water. She had the timers hooked up to the front door outside outlet. Most modern homes have all the outside outlets hooked up to GFCI outlets/breakers. So when it would rain it would trip the GFCI outlet. I was her fixit man and she wanted me to replace the GFCI outlet. I informed her it was doing its job properly and did not need to be replaced. If you reset the button the outlet functioned perfectly. Many people do not understand the real function of a GFCI outlet. In this case it saved her from coming up the walk and getting electrocuted stepping in a puddle. So just tread carefully replacing the outlet but in your case it may be the only option to keep your machine running.


Thanks for the response! That makes a ton of sense. I did a lot more Googling around on it as well, hoping there was a decent solution but I see it does just come down to the fact that some current is going to go to ground with a VFD, even if it’s just in the order of mA. I see a GFCI outlet trips when there is a difference of 4-6mA. I have three circuits going into the garage and only one of them has a single outlet. I ended up swapping that outlet from GFCI to a single receptacle outlet so it could be argued that it is only powering the single appliance (the VFD). It is also the only outlet on a wall shared with the house / furthest from the garage door, so it’s least likely to see any sort of moisture. I definitely don’t wash my car in the garage either :laughing:

After swapping the outlet I was able to get the spindle running all the way to it’s max 24000 RPM! Now I’ve just got to tram it and cut some stuff!

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