The electrician asked me, 3 or 4 wires...

[Phil Winn]

(I live in CA, but am in MA for a short while, so I am dealing with the electrician over the telephone...)
The electrician I hired gave me a few options...he said that he could either hook-up the 220V 30Amp outlet with:
1. A 10/2 cord; one white wire & one black wire &
one green wire; all ten gauge.

OR
2. A 10/3 cord; one black & one red & one white &
one green wire; all ten gauge. He said that this
would make the "wiring" much safer and would
only add a few $$$ to the final price. (I am NOT sure of this, but did he say that there would be a nuetral and a ground; and the two hots needed for 220V?)?

He said that he could either hard wire it (with quick "off"), or for a few dollars more, he would use 220V 30Amp 4 prong plugs-male and female...The expensive part s getting an electrician to come to the shop, the additional few % doesn't make a difference. Do you agree with him about the 4 strand wire (10/3)?
Thanks,
Phil
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[Mike Cutler]

Yes I do. Both ways will work, but his way gives you long term, down the road, future improvement capability. If he is there and everything is in place put in the 10/3. You may never take full advantage of the extra conductor, but it's there.
As far as the hardwire, vs quick disconnect. That is up to you. I personally like plugs on my machines so I can move them in the future.

[Sparky Paessler]

I agree with Mike go with the 10/3. I also like plugs on my tools.

SP

[Byron Trantham]

Our local code requires four wire, an "extra" ground wire. Never have figured out what this gets you but you "can't fight city hall." :D

[Keith Hooks]

I'm confused - what do you do with the extra ground in a 10/3 bundle when you're wiring for 220? Do you connect both the white wire and the naked wire to the ground terminal on the receptacles? What does this buy you? I didn't think the neutral was used at all in a 220 circuit.

Also, I've noticed that both the neutral and the naked ground terminate at the same point in the panel. The difference is that the neutral is intended to carry current while the ground only does so if something goes wrong (from my understanding).

Any clarification is appreciated!

Also, I would definitely add the plug. That way you can unplug the tools and lay the cord across the table so you know for sure that the tool doesn't have power to it.

[Jim Becker]

Keith, the fourth wire (white) is capped off and unused in this application. It's only needed for 120v circuits and in that case performs the function as neutral...which is not the same as ground. Yes, they are tied at the main panel (not in a subpanel), but they are still different conductors with different purposes. It isn't needed for a 240v tool, but as some suggested, certain municipalities require it anyway, even though you are not installing a dual-voltage appliance.
-----

Phil, I also suggest the twist-locks for plugs/recepticles. I don't like hard-wired tools with disconnects....too inflexible, even if you only need to move things occationally for cleaning. The twist locks cost a little more than plain plugs but they don't fall out of the wall and provide positive contacts. All of my 240v tool circuits are 12-2 with ground or 10-2 with ground, depending on the amperage. The fourth conductor is not required around here for this application.

[Jim Becker]

Sparky, the ground does not get left unterminated in the box if it's plastic...it gets terminated on the ground lug on the plug/recepticle. If in a metal box, same thing but the ground is also pigtailed to the box to ground it, too. The white wire, in the case of 10-3 or 12-3, can be left capped off in the box if it's not used by the machine...which it would not unless it's a dual voltage appliance.

[Phil Winn]

The electrician emailed me and said that the plugs for the four wire have...yes you guessed correctly, four "blades"; onblack (hot); one red (hot);
one green (ground); and one white (neutral). Jim Becker, should the extral wire be capped off, or is this plug different? Yesterday on the telephone, I THOUGHT
he said that the Black & Red went to hots, and on a "main panel", the neutral and the ground breaker box bars were connected---but the neutral green wire goes to the ground bar and the white goes to the neutral bar.

Is this correct?
Thanks,
Phil

[Keith Starosta]

Our local code requires four wire, an "extra" ground wire. Never have figured out what this gets you but you "can't fight city hall." :D

Byron, I'm dealing with our lovely Stafford County inspectors right now! Always a treat.... :rolleyes:

Keith

[Jim Becker]

The neutral can certainly be physically connected on the appropriate lug of the 4-prong plug/recepticle, but will have no connection on your machine...that conductor doesn't exist on the machine's motor or cord.

[Charlie Plesums]

As several have said, that white wire is only used if you want to add a 120 volt outlet or lamp or something at the machine, and normally there isn't a place to connect it at the machine.

When I put my big machine in, I wanted to run 4 wire, for possible future use. I found the stiff heavy four wire cable, but prefer the more flexible cable (still the same wire gauge). I could not find 4 wire in the flex cable, so dropped back to the three wire connection - all the 240 volt machine needs (unless it is moved to Virginia, where the electricity must be different).

Code and common sense require a disconnect close to the machine, but the plug (preferably twist lock like Jim says) provides that function, as well as adding flexibility.

You seem to have an electrician that is more knowledgeable than many about wiring machinery. But just in case, the locking plugs that you need for the 3 wire 240 volt connection have a NEMA code of L6-30P (or L6-30R for recepticle). The NEMA code for the four wire 120/240 volt connection are L14-30P and L14-30R

[Jim Becker]

I THINK last question for this issue.....so if I get the 4 wire cord, should I pay for the 3 or 4 prong plugs?

Phil, you asked this question via PM, but your PM mailbox is now full...you need to delete messages or you will not be able to receive/send via that system.

You'll be hard pressed to FIND a 4-wire cord for your tool--but rubbber-coated three conductor is easy to find! If your code requires, use the 4-prong hardware for the circuit and plug at the end of your tool cord. You just will not have a connection for the neutral (white) wire at the machine/machine cord.

[Mike Cutler]

Phil. Your electrician is steering you in the right direction. It seems that he has a firm grasp on the situation, and recoginizes your actual needs.
I would expect that all the conductors will be properly terminated at the "wall receptacle" and that he will just "drop" the white wire on the machine plug.
To clarify a point. The white neutral is really not an "extra ground" it may be explained that way, or made easier to understand, but is really not "ground"
Neutral is exactly that, Neutral. It is the center tap of the "Y" connected transformer on the pole. All of the loads hooked up to that specific phase in the transformer can be said to "share" the same neutral. Ground, however is just that, the ground potential is "unique" to your residence.
In a perfectly balanced system, with all grounds at the same potential, and the insulation resistance of all ground rods and conductor the same, ground will be the same "potential" as neutral. I have to worry about "floating" grounds, and cabinet commons( some are 125 volts, diode suppressed above ground!) at work, but in the home we can say that ground is the same potential as neutral, in the abscense of a fault.

The connection scheme that the electrician explained to you is electrically correct to mitigate circulating ground currents due to potetntial differences.
His explanation is the "bonding strategy" used in residential applications. you want him to do what he is explaining.

Addy protocol. I am not a liscensed electrician, but I have been working in power generation field for 20 years. I don't claim to know the codes, but I know how the 'trons have to flow.

[Keith Hooks]

I thought for sure that the last time I looked in a panel that the neutral bus and ground bus were actually connected. I remember thinking - "That's strange" and wondering at the time what the deal was.

[Neal Flatley]

Just my .02.. Even if you think the only thing that will ever be plugged in will be a 220 machine, run the neutral anyway. If you ever need to add a motor starter or contactor, its a lot easier to find these on the used market with 120 volt coils. I had to add a control transformer in order to use the motor starter I had because the 220 circuit was run without a neutral.

[Mike Cutler]

Keith. What you observed is correct. Neutral and ground are "bonded" at the main panel.
Without typing another lengthy post, like the above( I only type about 8 wpm). The distinction is relative, electrically to the transformer center tap. It also keeps everyone on the same page so to speak with terminology.
As an example. it is possible to lose your ground and have neutral remain intact( Dangerous also!) and you can lose your neutral between the service and the pole, but keep ground and have a different dangerous condition.
You also may not immediately recognize that this has happened.
It seems like wiring is easy, I mean there are only 3 or 4 colored wires right. Yet it seems to defy the laws of mathematical probabilities the number of incorrect ways people have messed it up, yours truly included.

:eek:

[Phil Winn]

The electrician will use the 10/3 (4 wire) cord ! He didn't seem like a happy
camper on the telephone "that 10 gauge wire is a bear to work with, but the
10/3 really is the pits-I will have to charge more". Oh'well, he only added
$5.00 per outlet for working with the 10/3 so it isn't that bad of an upcharge.
Should be done by tomorrow night! SMC-thanks for the help!
Phil

[Jim Becker]

I can understand your electrician's angst...a little. I used 10 guage rubber 3 conductor for the cord on my MiniMax FS 350 jointer/planer and it was quite a bit harder to deal with than the 12 guage product, although not by magnitudes.