NEMA 6-30 vs. 14-30 for WWing machines.

[Brian Tax]

I have a new Hammer J/P combo that recommends 30 Amp breaker. I have wired driers and ranges before, but not any 220 machines. Correct me if I am wrong, but the only difference in the 14-30, is that there is a separate ground from the neutral?

Is there ever a case with WWing machines that I would have to use 14-30 over 6-30. The J/P only has 3 wires, so 6-30 makes sense, but I am thinking of using 14-30, just to make sure I have any future requirements. If there is no possible need for 14-30, then I will just go 6-30.

[Jason Beam]

I can't identify the plugs you mention by their numbers, but I can offer this:

The only reason to have a 4-wire 240v plug is if your machine needed 120v for some auxiliary components like a light or some such. Otherwise, the neutral is not needed and you don't need a 4-wire plug.

As always, the manual will tell you the power requirements for that device.

[glenn bradley]

As Jason says, your fourth wire is not needed for most woodworking machines I have dealt with. Does the Hammer have 110v lights or gauges built in? This would be similar to the clock and lights on a 240v electric range or electric clothes dryer that uses the 4 wire configuration.

[Don Jarvie]

You only need the 6-20 for WW machines so use a 3 prong plug that rated for 30 amps. They come either flat like a dryer plug or straight in like a regular plug.

[Tom Veatch]

...Is there ever a case with WWing machines that I would have to use 14-30 over 6-30. The J/P only has 3 wires, so 6-30 makes sense, but I am thinking of using 14-30, just to make sure I have any future requirements. If there is no possible need for 14-30, then I will just go 6-30.

If and only if you run a combination 120/240 (2 hots, 1 neutral, 1 ground) circuit will the NEMA 14 devices be usable. You need that type of plug/receptacle if and only if your load requires both 120v and 240v simultaneously. If you're going to use an electric range or clothes dryer in your shop, they'll need a type 14 outlet, but I've never seen any woodworking machines that do. Not saying there are none, just that I've never seen one.

I have 120/240 4 wire circuits in my shop to get 240 and 120 to each machine location, but the receptacles are dual voltage - duplex receptacles which have one NEMA 5 and one NEMA 6 outlet in each device. No NEMA 14 devices in the building.

[Rod Sheridan]

Brian, you must have the A3-41 to require a 30 ampere circuit?

The machine only requires two lines plus ground, so the receptacle for it would be a two pole plus ground.

I have the Hammer A3-31 which is marked as requiring a maximum of 16 ampere overcurrent protection so I use a 15 ampere circuit for it.

Regards, Rod.

[Brian Tax]

Thanks for the responses.

Tom, so you run 2 hots and a neutral to the 220, and use one of those hots and the neutral to the 120, is that correct? That seems like a pretty good idea.

Rod, I have the A-3-31, I think that I am finding some inconsistencies in the documentation. On the cord it's self they put on that it needed 30 Amp, but the wires were only GA, then I found in the documentation last night the 16 amp. Also the manual keeps referring to the "Assembly instructions" , which are no where to be found.

[Tom Veatch]

Tom, so you run 2 hots and a neutral to the 220, and use one of those hots and the neutral to the 120, is that correct? That seems like a pretty good idea.


That's right, Brian. I specified that arrangement when I had the shop built. The receptacles are like these (http://www.leviton.com/OA_HTML/ibeCCtpItmDspRte.jsp?item=8120&section=10928). The electrical contractor had never heard of them. I had to do a web search to find a supplier/model number for him.