Wiring PM 12x36 lathe, PM 9x32 mill

[RockwellHardness]

Help: Wiring PM 12x36 lathe, PM 9x32 mill

​​​Hello all,

I have my new PM mill and lathe in the shop, and need some help with the wiring. I have a sub panel in the shop, with a 20 amp 240 volt breaker not being used for anything.

I bought a 12/3 cord, one female and two male 240 volt plugs. I plan on wiring the 12/3 cord into the sub panel, and then plugging in the lathe or the mill each time I use them.

The 932 has a wiring diagram, the lathe does not. the 932 mill has the three wires labeled, ground (green and yellow) brown, labeled L, and on the wiring diagram it shows the L brown wire going to the breaker so I assume that is the hot, and the grey wire labeled N, which I assume is the neutral. The lathe wires are not labeled, but are essentially the same colors, Brown, Black ( not grey ) and yellow green.
So what do I hook up to the breaker, just the brown, and how do you put one wire across the two halves of the breaker ? hew:

Thanks,
RH

 

[Sparkymacker]

Re: Help: Wiring PM 12x36 lathe, PM 9x32 mill

Hmmm...well if you are hooking it up 240V there is no neutral. You need to confirm what the voltage of the units is first.

​​​Hello all,

I have my new PM mill and lathe in the shop, and need some help with the wiring. I have a sub panel in the shop, with a 20 amp 240 volt breaker not being used for anything.

I bought a 12/3 cord, one female and two male 240 volt plugs. I plan on wiring the 12/3 cord into the sub panel, and then plugging in the lathe or the mill each time I use them.

The 932 has a wiring diagram, the lathe does not. the 932 mill has the three wires labeled, ground (green and yellow) brown, labeled L, and on the wiring diagram it shows the L brown wire going to the breaker so I assume that is the hot, and the grey wire labeled N, which I assume is the neutral. The lathe wires are not labeled, but are essentially the same colors, Brown, Black ( not grey ) and yellow green.
So what do I hook up to the breaker, just the brown, and how do you put one wire across the two halves of the breaker ? hew:

Thanks,
RH

 

[Ray C]

... Make all the connections with the main shut off for safety.

In a 240 single phase system, there are two hot wires and one neutral/ground. To connect the male plugs to the pigtails on the machines, connect the ground (green/yellow) to the ground wire of the plug. Connect the L wire to one of the blades and the other N wire to the other blade.

For the female plug, connect the ground prong to the ground/neutral wire (probably a bare wire if you bought romex). Connect one of the blades to one of the other wires (probably black or white) and connect the other blade to the remaining wire.

In the box, take your piece of 3 conductor wire and take the bare ground wire and connect it to the neutral bus in the box. The 240v breaker has two terminals. Connect one of the other conductors to one of the terminals and connect the other wire to the other terminal.

Before plugging anything in, turn on the power and use a volt meter to check the female plug between the ground prong and either of the the other prongs. It should read 120. If you check between the two flat prongs, it should read 240.


Ray

 

[RockwellHardness]

... Make all the connections with the main shut off for safety.

In a 240 single phase system, there are two hot wires and one neutral/ground. To connect the male plugs to the pigtails on the machines, connect the ground (green/yellow) to the ground wire of the plug. Connect the L wire to one of the blades and the other N wire to the other blade.

For the female plug, connect the ground prong to the ground/neutral wire (probably a bare wire if you bought romex). Connect one of the blades to one of the other wires (probably black or white) and connect the other blade to the remaining wire.

In the box, take your piece of 3 conductor wire and take the bare ground wire and connect it to the neutral bus in the box. The 240v breaker has two terminals. Connect one of the other conductors to one of the terminals and connect the other wire to the other terminal.

Before plugging anything in, turn on the power and use a volt meter to check the female plug between the ground prong and either of the the other prongs. It should read 120. If you check between the two flat prongs, it should read 240.


Ray

Hi Ray,

Thanks much, the wiring diagram confused for me, but then again I do not know how to read a wiring diagram ! Your instructions I understand, and jive with what I read in my how to do it electrical books.

And Thanks as well to Sparkymacker.

RH:man:

 

[Hawkeye]

Sorry, Ray. I don't often disagree with anything you say. Please don't connect the ground wire to the neutral bus. Connect it to the ground screws at the back of the panel. 240 volt wiring doesn't have a neutral. 120/240 volt wiring does (like your range or dryer), but that will have an extra wire.

Most types of wire are sold with the designation based on current-carrying conductors, like Romex. #12/3 will have three insulated conductors (red, black and white) plus a bare ground. Cabtire cable (extension cord), on the other hand is sold by the total number of conductors. #12/3 will have three insulated conductors, but one will be the green (or yellow/green) ground wire, with no bare wire.

When you are using 3-wire cabtire cable to run 240 volts, it is okay to use the white wire as one of the hots. Just be consistent at both ends.

 

[Ray C]

I don't think we're disagreeing... Here's what 12/3 Romex looks like so, you need to connect white and black as hot and the bare to the box neutral/ground bus. There are indeed 4 conductor 240V cables but I don't think this is what he has. I'm pretty sure the NEC/NFPA changed the rules this year and for electric dryers and stoves, you need to use 4 wire systems and carry a ground to the appliance.

Sorry, Ray. I don't often disagree with anything you say. Please don't connect the ground wire to the neutral bus. Connect it to the ground screws at the back of the panel. 240 volt wiring doesn't have a neutral. 120/240 volt wiring does (like your range or dryer), but that will have an extra wire.

Most types of wire are sold with the designation based on current-carrying conductors, like Romex. #12/3 will have three insulated conductors (red, black and white) plus a bare ground. Cabtire cable (extension cord), on the other hand is sold by the total number of conductors. #12/3 will have three insulated conductors, but one will be the green (or yellow/green) ground wire, with no bare wire.

When you are using 3-wire cabtire cable to run 240 volts, it is okay to use the white wire as one of the hots. Just be consistent at both ends.

 

[Ray C]

BTW: Here is 12/3 BX cable. When I lived in Illinois, most jurisdictions allowed you to use the metal outer shield as the ground. I haven't kept up with the NEC and don't know if that's still allowed. It was when I sold my house there about 15 years ago.

 

[charlton]

I think the point here is that neutral and ground are not the same thing so the term "neutral/ground" might be a bit misleading. In 240 the non-hot wire goes to ground. I believe the white wire should be taped black or red to indicate that it's hot (at least that is the code here).

Note: I am not an electrician though I have studied the local code before.

Cheers,
Charlton

 

[Ray C]

You are indeed correct, the term neutral/ground is confusing. Complicating matters is that different regions have different codes. Where I live, the center tap of the low voltage side of the supply transformer is the neutral and it is tied directly to ground at the transformer. Also, I live in an area with very sandy soil and we have all underground wiring. The neutral wire coming into the service panel serves the neutral bus. That neutral bus is not isolated from the metal box of the service panel and furthermore, there is a heavy wire connected to that bus that runs outside to a copper bar pounded into the ground next to the house foundation. At least in my area, it's a combined neutral/ground bus. This is because we have underground power and if anyone ever cut the ground wire at the transformer (which is 200 feet away in my neighbor's yard), things would go unbalanced (causing damage most likely) if you didn't have the local house ground. Our underground mains are 15,000V so they're not taking any chances. It's possible that areas served with above-ground power, have different grounding regulations.

You are indeed correct though, the ground prong we were talking about should go to the ground connection in your service panel. In some cases the ground and neutral are one in the same.


Ray

I think the point here is that neutral and ground are not the same thing so the term "neutral/ground" might be a bit misleading. In 240 the non-hot wire goes to ground. I believe the white wire should be taped black or red to indicate that it's hot (at least that is the code here).

Note: I am not an electrician though I have studied the local code before.

Cheers,
Charlton

 

[arvidj]

The neutral wire is the return line for the load current.

The ground wire is a low impedance path to the earth that is a safety device.

The neutral can be, and is often attached to, an earth ground at the service entrance. In that situation the neutral is indeed 'grounded'.

The ground can never be used as a 'neutral', assuming safety is your first priority.

The neutral and the ground will very likely be attached to one another at the service entrance where they are both attached to a 'ground rod' driven into the earth. They must never be attaced to one another in a sub-panel or appliance or motor or ..., again assuming safety is your first priority.


If safety is not your first priority then you can do what ever you want.