220 saw & dust collector wiring question

[Tom]

I have a Grizzly G0444Z table saw and a G1029Z dust collector. Both run on

220. The saw cord has a green wire which is ground and a red and black which are both hot and the dust collector cord has the same. Both draw 15 to 20 amps. I have 12/2 with ground romex cable (white, black and bare ground wires). I was told by Grizzly to use a 20 amp/220 double breakers on both and 12/2WG and color the white wire as black or red. I think they said each motor has capacitors, what ever that means. What confuses me is in the past when I wired a 220 circuit I always used 12/3WG ( red, black, and white with a bare ground wire). Have any of you wired your saw or other machinery like Grizzly told me to? In addition to grounding my dust collector vacuum lines I was thinking that I would go a head and run a ground wire on each unit to the cold water pipe for added protection. I would appreciate any advice you could offer me. Thanks a lot.

[Greg]

You really only need a white wire if you have a 120v load. A pure 240v load only needs to hots and a ground.

[zxcvbob]

If you were using conduit and seperate conductors, you would use 3 wires: black, red (or a 2nd black) and green (or bare). Since you are using a 12/2 cable, you can use the white wire for one of the "hot" conductors if you wrap black, red, or blue tape around the ends of the insulation or paint with some red nail polish.

The ground wire in the cable should be adequate; don't mess with the water pipes.

If you are using plastic pipe for the vacuum lines, run a bare wire (it doesn't matter what size) inside the lines from end-to-end and ground to the metal housing somewhere to dissipate static.

HTH :-)

-Bob

[toller]

All things being equal, it is better to use 12/3. You have no use for the neutral (the white wire) now, but some day you might, and it is no harder to run 12/3 than 12/2. It gives you the option of having 120v for a light or something if you need it. I ran 12/2 and regret it.

However, if you run 12/2, Grizzly is correct. Just use the two insulated conductors as your hots, no neutral needed.

I haven't grounded my "vacuum" lines, but some people do.

Are you sure the tools take 20a at 240v? What are they, 4hp?!

[Tom]

Both are 2 HP each.

[Joseph Meehan]

Without a 120V load you don't need the neutral. In fact there is nothing to connect it to.

Don't do this. You could be creating a dangerous situation. In many homes the cold water pipe is not a suitable ground and some errors could cause them to go live. Unlikely but possible. Just use the ground provided by the circuit.

[toller]

2HP is typically between 8 and 13a.

[Terry]

If the dust collector is also 220 volt then could be wired same Red/Black and a ground, same as the 220v. saw. AIUI Various electrical codes allow one to use White/Black instead of Red/Black. But if white is used as 'one side/leg' of 220 then it should be taped/sleeved and/or colour coded to clearly show that wire is being used instead of a red wire. In other words if you don't need to wire a neutral you don't. Typically our 220 volt hot water tank does not use a neutral, neither does our 220 volt dryer; so the white wire is left disconnected. Our 230 volt stove DOES use the white neutral. Our 220 volt bench saw, which can be mover around a little, has a heavy White/Black flex with a green ground. White is one 'side' and black the other of the 220 volts.

[Terry]

"

I agree with the Irish tiger. Don't. If bonding to cold water or other services is required my understanding also is that it is done once at the main service entrance panel. Not random connections to piping that may or may not be contiguous through the house plumbing back to a cold water supply system that itself may or may not be a good electrical ground. AIUI this is not the same thing as a requirements, in some countries, to electrically 'bond' together certain metal pipes etc. within say a bathroom where there are electrical appliances, to avoid voltage differences, in the event of a fault within that area.

[John Hines]

No that is what the ground wire in romex is for. I'd suggest connecting up a metal box, to plug the DC into, and connect up the ground wire to the ground lug of the receptacle. Connect up any metal ductwork as well to this ground.

If your concerned about grounding, use emt instead of NM (romex). Mounting emt and metal boxes on the wall surface works really great for workshops.

And be sure to use a double pole switch, or better yet like an A/C disconnect that is rated for a 2hp motor if you want a shutoff.