I was gone for a few weeks, came back, tried to run some files on my Onefinity and the GFCI keeps popping. My whole shop is set up with them. Plugged it in to a few different ones, same result. It’s fine until it gets to about 6,000 rpm, then I start hearing clicking from the back rail, then the GFCI pops.
Suggestions?
Try a non gfci outlet. Generally, all hobby Vfds will pop gfci breakers/outlets due to their nature.
Consult your local electrician always.
I’ve been curious about this, since I’ve seen it come up several times recently.
[EDIT 2026.06.02 - Below I mention “RCD Type B” breakers, based on further reading this appears to be a European standard and likely doesn’t help anyone in the USA, I’m leaving in place because the information, other than locality, is valid]
I’ll start with the conclusion for those that don’t want to read the wall of text I’ve written below: At the end of the day it looks like the solution to this is to utilize a “RCD Type B” breaker. From the white paper referenced below it looks like what these do is increase the trip current from around 50ma to 300ma and apply a small but still safe delay to tripping allowing the circuit to perform it’s protection duties. This at least is a starting point for a conversation with your electrician.
I’m going to preface all the below by saying that I’m not a electrician and the code I’m referencing is the United States NEC. Also important when referencing any code is that different municipalities have adopted different versions. For example, where I live they may currently adopt 2017 NEC 210.8 not the 2023 NEC 210.8 for inspection purposes. Therefore it’s important to consult with a local electrician or at a minimum your local building department to find out what version of the code they’re using.
I saw one poster whose electrician indicated if you mounted the outlet high-enough in your garage, it was not required to be GFCI. That exception appears to have been removed under the current 2020-2023 NEC 210.8, again depending on what version of the NEC your municipality enforces, that may not be legitimate: (Please see “Garage Clarification” here: GFCI Protection Requirements Explained (NEC 2020–2023))
I found a paper describing what is happening with VFD’s and GFCI’s if you are curious and like to read white papers (Who doesn’t first thing in the morning before the caffeine kicks in? Ahhh, life is bliss): VFDs-Tripping-GFCI-Breakers-Causes-Ground-Faults-and-Solutions.pdf (199.3 KB)
All the above being said if your local code requires GFCI protection in your garage you ABSOLUTELY should follow the code. If you are not following the code and you have a loss in your home due to removing that safety device, then you risk personal liability and it’s hypothetically possible that any insurance you carry may deny your claim if they discover code you were required to follow at the time your garage was constructed wasn’t followed. Building codes can be a real pain in the ass but at the end of the day they aren’t in place to protect you but rather a future owner, at least that’s how one inspector explained it to me when I was rebuilding my house. The more compelling argument in my mind is, codes are written in blood, meaning they usually are created after enough bad things happened that the industry decided we can do better.
One of the reasons I believe there aren’t more people with this issue is that the code requiring GFCI’s in garage is still somewhat modern. My garage/shop was built about 25 years ago and there isn’t a GFCI in sight, and my whole house was inspected 15 years ago during reconstruction, and the garage situation wasn’t mentioned as I’d done no work there so it fell under previous code.
Spot on. Recommendations to just bypass the GFCI are irresponsible even with the obligatory “consult an electrician” caveat to protect from liability. But it’s easier than solving the underlying issue which requires engineering & dollars.
It’d be interesting to see what a lawsuit would reveal if knowingly recommending a solution that bypasses a safety device that was required due to experienced losses, fires & deaths would find liability even in a situation where the installation was to code when the building was originally constructed. I expect in states like California, knowingly recommending a course of action that might result in death or property loss regardless of what was code at the time of building would likely be bad for the advice giver. CA juries have been known to find manufacturers guilty when products were advertised as “new and improved” because it implies the older version was flawed.
Fortunately for OF, they’re unlikely to be sued because an owner whose house burns down isn’t going to volunteer they did something dangerous and jeopardize their insurance payout. And unless there’s something egregious at the outlet, a claim adjuster isn’t likely to catch it.
In this situation, at least based on my understanding of the white paper I read, the issue isn’t necessarily the VFD/Spindle, but rather using a device that has more traditionally been used in industrial settings, rather than residential ones where the fix is to upgrade the on premise GFCI device rather than changes required in the equipment. Not that a poorly designed VFD couldn’t cause issues after upgrading a GFCI with a RCD Type B breaker. Again, in my reading on the subject, this has become a more common issue even with electric vehicle chargers as folks are installing those in their homes.
FWIW, I don’t believe GFCI protect from fire risk rather they reduce electrocution/shock risk. I think the Arc-fault breakers (I had to install a bunch of these in 2010 during renovation) help protect against fire on a higher level than just the regular breakers do with their job to trip when you overwhelm the rating of the installed wiring (also a fire risk).
Fundamentally, a GFCI protects against faults to ground – that is, the current flowing from the wire finds a path to ground that does not include the proper return path through the GFCI socket or breaker. That “non-proper” path is usually a human who is properly grounded. In those rare cases such faults cause a fire through arcing. I’m not too familiar with arc fault breakers, but I believe they protect against ground faults as well as short duration arcs, which is usually what causes a fire.
I’m not sure any amount of engineering and dollars can solve this problem per se - at least on the VFD side.
A possible solution is making the GFCI connected to the VFD less sensitive to misaligned current flows or using some sort of galvanic isolation to break the current flow - I believe that is what commercial solutions use. I don’t know if residential code permits either solution or not.
All that said, I do believe the response from OF is (a) insufficient, (2) flippant, and (iii) embarrassing. And (IV) perhaps even BS. As Jim points out, pushing the liability on to the consumer is shedding the responsibility of creating a product that works within code across a wide swath of their customer base. I admit this problem is not an easy problem to solve, but making it the customer’s problem is irresponsible and decidedly customer un-friendly.
Perhaps this is just an exemplar and problem of using quasi-industrial equipment in a non-industrial setting?
Regardless, a proper solution is warranted.
+/- 0.02
-Tom
I’ve done a bunch more reading this morning, trying to get a better feel for the subject, and yes, I believe this is the case.
In the summer of 2025, in preparation for the changes to the 2026 National Electric Code in the USA the industry has addressed specifically GFCI nuisance tripping in regards to Variable Frequency Drives as they’ve become more common in a number of residential devices such as air conditioners, refrigerators, washing washing machines, etc.
In pursuit of addressing that issue they’ve instituted standards for high frequency tolerant GFCI’s.
The VFD’s that are in use for our spindles are not specifically addressed by code, but the underlying reason for most installed GFCI’s suffering nuisance trips is the same.
I did not have much luck finding HF-GFCI complaint breakers though I get the impression they’re being manufactured but new enough that they aren’t generally available to consumers through online retailers.
Essentially folks in this situation are caught at the cross roads of increasingly strict safety standards (i.e. - how often and where GFCI’s are required in the NEC code) and the equipment required by those standards not gracefully addressing, what were previously edge case use issues, such a VFD’s in residential settings. As VFD’s are entering mainstream residential use, the standards and capability of the equipment are evolving, and a solution that may be available using HF-GFCI’s don’t seem the easiest to source.
I want to finish up by stating during today’s journey, I found that “RCD Type B” breakers, while accomplishing very similar goals as HF-GFCI’s in the USA appear to be a European standard and don’t seem to be readily available for residential use in the USA and likely aren’t covered by NEC code.
Your milage may vary, and this hasn’t been the easiest subject to pursue, but hopefully some of the above references will help those with nuisance GFCI trips understand what’s going on if not help solve the issue immediately.
Regardless, this is not a new thing. For OF specifically they’ve been selling formerly industrial equipment for residential consumer use for years. There are many others doing the same thing. A simple caveat or warning in their sales, marketing & ordering information would suffice to let customers know what they’re potentially getting into. Other industries have dealt with the same customer crossover issue (I’m looking at my welder, plasma cutter and laser cutter); this is something OF should be up front about so customers know the potential issues and solutions or non-solutions that may be available to them.
Non electrician here
Why does 1F use a 3 phase motor for their spindles? Hence requiring a VFD.
Is there a single phase motor that would work or is it a size issue?
Asking for a friend
[Edit: 2026.06.03 - (“3-Phase DC” below is VERY poorly stated on my part, VFD’s convert Single Phase AC to DC which is generally converted to 3-Phase AC which can be output at both variable frequency and amperage in order to control a 3-Phase AC motor)
To the best of my knowledge, spindles are controlled as a variable frequency (3-Phase DC).
I’m not immediately aware of any motors that offer the same functionality as a VFD and communication with control units that don’t function that way.
Of course you can absolutely use a router, but you do loose some features if you… errr… ‘go that route’.
So, in theory you can install a standard breaker and put a HFGFCI outlet as the first in the circuit and wire the rest in series which would make the entire circuit GFCI. I don’t know if it would be to code, but it would serve the same purpose as the GFCI breaker.
Have you found a source for HF-GFCI outlets?
Personally this isn’t an issue for me, due the age of my shop, I do not have a GFCI requirement, but I’d love to see the community leverage it’s broadband expertise to maybe help other folks out who are struggling.
The sort of VFDs we are talking about are powered by single phase AC. 3 phase is limited to industrial applications, and then, only in certain circumstances (like large motors). There might be some sort of “3 phase” within the device itself as LM mentions, but as far as I know, there is no such thing as “3 phase DC” – 3 phase literally means 3 separate sine waves, 60 degrees out of phase - impossible to accomplish with DC (e.g., no sine wave). It would be possible to create “3 phase” “DC” using three separate PWM frequencies offset by 60 degrees, but I don’t know what that would accomplish like 3 phase AC does. Time for a little googling 
-Tom
?
Looks like someone already went through this back in 2022
They say there’s a part in the NEC that allows for non GFCI in single use devices like a what you would need for a 220v spindle
https://forum.onefinitycnc.com/t/hy-2-2kw-spindle-popping-my-gfci-outlet/13332
@cyberreefguru - You are absolutely correct about my “3-Phase DC” statement and I’ve edited my initial comment to clarify a very poorly stated comment.
More properly most VFD’s convert singe-phase A/C to D/C then back to 3-Phase A/C which can be controlled in order to adjust both the speed and torque of a 3-Phase A/C motor dynamically.
This is why it’s so important to consult with a licensed electrician and the building department in your region before making any changes to installed safety equipment.
In the United States, the NEC is updated every 3 years, the most recent update is this year in 2026. It is the recommended ‘model code’ but not the actual code itself. Some municipalities update their code very quickly with others lagging several iterations back, so your local electrical code can be based realistically anything from the 2017, 2020, 2023, or probably not likely but possible the current 2026 NEC.
What iteration you are required to follow is based on what was in your localities code at the time that work was permitted and performed at your house. Where I live, ANY changes made on your structure are supposed to be permitted and inspected and meet whatever standard is in force in your code at the time.
The above is what makes it so hard to give anyone solid advice because of the large degree of variables and the incredible speed of changes surrounding GFCI implementation between even the 2017 and 2026 NEC.
Are many of us running circuits not protected by GFCI’s, absolutely. Are there many different rules used where those circuits are valid and legally installed at the time, absolutely.
Can you use an older NEC to justify removing a GFCI from a circuit, probably not, though you may get away with it if you have a problem.
Should anyone recommend you remove a safety device because many people aren’t using that device and have no issues, in my opinion, hell no!