Spindle wiring help

Hey guys I am getting close to making my first cut on my build.
I see the machine came with a NEMA 10-30 plug which is an obsolete dryer plug here in Canada.
This plug wiring calls for two hots and Neutral, no ground. (?)
I assumed purchasing the machine it would run on standard 220v wiring with a grounded circuit.

How are you guys wiring your spindle plugs?


There is no neutral wire in there. Just 2 hot and a ground.
I wired my receptacle that way at least and it works fine. Someone in the forum showed also wiring in the power supply inside the electronics and I recall he showed no neutral wire in there.
I suggest to open the controller box and double check the wiring for your own safety.
Hope this helps.


Yes, the NEMA 10-30 outlet is an ungrounded device which is why its generally no longer used and was supposed to be replaced with the NEMA 14-30. Unfortunately now all sorts of companies are make electric vehicle chargers with that plug. You can get a replacement cord or simply cut the end off and wire in your preferred outlet such as a NEMA L6-20 twist lock since the drive doesn’t need a neutral wire. The machine end is an IEC type connector which is common for IT hardware such as routers, switches and servers so you could also buy a replacement cord.

The 10-30 is not an ungrounded outlet, it’s a 220 with no neutral. Only stoves and dryers and such have a neutral in the outlet because they typically use both 110 and 220. Usually only the heating elements are 220.

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Terminal “W” is the neutral. I’ve seen receptacles wired both ways but is supposed to be a neutral.

5207-Wiring Diagram

That diagram literally shows W is a ground.

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Neutral always ends up back at ground.

Take a look inside your electrical panel.

If I’m on a rooftop and I’m going to pump down a condenser I have a pigtail I can clip to ground and one of the hotlegs of a 220 compressor so I can run my 110 vacuum pump. It’s backwards in practice to the scenario but it proves the same point.

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The diagram illustrates that W (which is common or white wire by code) is grounded at the main panel. Compare to the nomenclatural of the wiring for a 14-30 which is the more modern replacement for the 10-30.

Document-34001-Wiring Diagram

Details in the link but the short version is
“NEMA 10s are classified as 125/250 V non-grounding (hot-hot-neutral), and were designed to be used in a manner that indirectly grounds the appliance frame to the neutral, which was common before the requirement of a separate safety ground was incorporated in the National Electrical Code.”


I was speaking with Langmuir tech support and they did say it should be wired hot, hot, neutral.

Not really keen on that scenario as was hoping to use my already installed 220v circuits I have for welders etc.

So sounds like guys have had no issues doing this with their machines?

I should have specified in this use case, since it’s a 240V single phase motor. If you have modern wiring, it should be connected to ground. It is 220 only and doesn’t need the neutral. I don’t like that they used that plug, I cut it right off of mine and wired it direct to a breaker in a sub panel. That said, it doesn’t really matter for function whether it’s ground or neutral since it’s only a 220 circuit.

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I cut the end off my wire and put on the 50 amp plug that my welders and plasma cutter use, since an extra outlet for that could maybe come in handy, been working great.


Same here. I use the same plug for TIG welder and MR-1. Just have to remember to plug in the spindle before starting!

Some tumble dryer ovens etc. use the neutral and one of the 220V phases (in the US) to tap 110V for energising other circuitry (timer, display, lights etc.). In this scenario you do not want to use the ground, because you will be sending a ground current (even though ground is connected to neutral at the main house utility connection).

The MR1 only uses this wire as a ground for protection (not to tap a 110V) and thus it is best to have the wire be used as a ground.

I replaced the plug on my MR1 with a 6-50 welding plug and wired it to ground. This can be typically dangerous since the 6-50 connection is capable of delivering 50 Ampere and the pigtail is not designed to handle 50A in case there is an issue. Fortunately the MR-1 has a 20A fuse, so this should be OK in the event of failure.