VFD Wiring Question

Mitmo303 · Apr 10, 2020

Hello all,
Please forgive me if this has been posted before. Im still learning my way around the forum and my searches for a related thread was unsuccessful.

I have a KBAC24D that I have had for a while. Had it wired up in my old house with no issues. My old house had a 3 wire 220v outlet that I wired to the VFD... Pretty straight forward. My new house has a 4 wire 50 amp plug that I need to wire to the drive. Anyone know what I need to do with the neutral white wire for power in for the drive? Just cap it and connect the usual three?

Any help is greatly appreciated.

Thanks,
-Mitch

EPAIII · Apr 10, 2020

Your VFD ran just fine without a neutral connection and it should continue to do so. It does not need a neutral connection. You are probably using a new, four wire cord with the four wires. So, yes you can just not connect the neutral wire. Put a wire nut or some electrical tape on it. And continue making chips.

Joe Gwinn · Apr 10, 2020

EPAIII said:
Your VFD ran just fine without a neutral connection and it should continue to do so. It does not need a neutral connection. You are probably using a new, four wire cord with the four wires. So, yes you can just not connect the neutral wire. Put a wire nut or some electrical tape on it. And continue making chips.

I have an electronics background. That's exactly what I have done on both VFDs. It all works.

Mitmo303 · Apr 10, 2020

Fantastic. I just needed some validation as this new 4th wire is a bit out of my wheelhouse. Much appreciated.

jim rozen · Apr 11, 2020

A bit of a back-story.

Older houses had dryer or range outlets where there was an exception allowing the grounding wire (green or bare) to carry a small
amount of neutral current for 120 volt loads like timers or lights. Newer houses need to have the neutral available to carry that current
now, the exception has been eliminated. So dryers, ranges need to have four wire cordsets.

Be aware that if you are running your VFD via a 50 amp receptacle, you need to size the wiring downstream of that for 50 amps.

If there is no dryer or range in use there, you might consider having that breaker replaced with a 20 amp or so sized one. Whatever
is needed for your VFD.

Joe Gwinn · Apr 12, 2020

Mitmo303 said:
Fantastic. I just needed some validation as this new 4th wire is a bit out of my wheelhouse. Much appreciated.

Speaking of older houses, and machines, make sure that the green wire connects the frame of the machine to the safety ground (bare or green wires) in the main electrical box.

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