Spindle and GFCI outlets?

I am looking at spindle options for my S4Pro in my garage. My garage has only gfci protected outlets. The internet tells me that VFDs and gfcis don’t play well together.

Is this true of the Carbide 3D spindle kit?

Aka, am I going to be likely to have problems running a C3D spindle plugged into a gfci outlet?

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Yes. It’s a fundamental aspect of the electronics.

Run an extension cord or work out a way to have a normal outlet which an electrician can install which still complies with local codes.


I have a Jet 12-21 lathe. When changing speeds it would pop the gfci so I replaced that single outlet circuit with a standard outlet replacing the gfci outlet. Problem solved.

Electrical code requires gfci protection almost every where. However there are conditions that preclude the use of the gfci. The variable frequency machines tend to bleed current back and that is exactly what a gfci is looking for. Pop goes the gfci. So on an individual basis it would require changing out the safety for practicality.

There are two ways gfci is implemented. The first is the circuit breaker is gfci. This protects all outlets on that circuit. The second is a regular breaker and the first outlet is a gfci type outlet and protects that outlet and all downstream outlets.

If the breaker is gfci you have to replace the breaker with a non GFCI breaker and removing protection from the whole branch circuit.

If the first outlet is gfci you can move that outlet downstream to leave the first outlet unprotected and from the gfci on protected

The simplist would to run a new branch circuit with no gfci. Although simplist it may not be the least expensive if you cannot diy it.


I just went through this and can add a little detail to what Guy responded. The first question is where the GFCI is. As he pointed out, there are two possibilities:

  1. In your breaker box, in which case one of the breakers will look like this:

  2. More likely, you will have the outlet closest to your breaker box in the garage with a GFCI built in like so:

In either case, you need to replace the device containing the GFCI with one that does not. If you have no experience working with electricity that can kill you, stop here and call an electrician. It won’t cost you much to get the swap done. I just swapped out the GFCI outlet after turning off the power to that circuit at the breaker box, and everything works well now.

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I have ran both my HDM and SO5 Pro, both with V3D VDF spindles in my shop. I have the in-outlet GFCI on all my circuits. I haven’t had them trip once with either machine on any of my circuits. The only caveat is that I use a power conditioning power strip for each machine and VFD. I don’t know if that alters the equation.


The power conditioning strip will likely have an impact, yes.

The cheap VFDs are very ‘noisy’ electrically, creating a significant amount of higher frequency harmonics back into the AC supply, this can easily cause a trip in a GFCI / RCD device.

A good power line noise filter can help this by removing a significant amount of the noise causing the false trips.

A bad noise filter can actually cause trips on it’s own however by creating a real earth leakage as it deals with the harmonics.

Either way, the GFCI / RCD is not particularly useful on the VFD as it only protects you up to the AC input into the VFD, you still have to treat the VFD output as the unprotected 3 phase power output it is.


I have also read claims that success / failure with the GFCI comes down to the combination of the vfd and specific gfcis.

What power conditioning power strips are you using?

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