220 recepticle wiring ?'s

[joe milana]

The wiring diagram on my 220v TS calls for two conductors and a "ground". I've hooked up the pigtail and plug, but when wiring the recepticle, does the "third", or "ground wire" as they call it, go to the ground bus or the neutral bus in my subpanel?

Thanks!

[Jim O'Dell]

All of mine went to the ground bus. Neutrals for 110 volt go to the neutral bus. Same for any neutrals on 220 for house appliances. But grounds always go to ground. Note: I'm not an electrician, but a master electrician gave me his good shop keeping seal of approval on my wiring. :D Jim.

[Rob Lineman]

220 v applications have no neutral, L1 and L2 originate at the panel from a 2 pole breaker. Ground is always to the ground bus not the neutral. 120 v applications originate at a 1 pole breaker (either L1 of L2 depending on breaker position in the panel) and a return path to the neutral bus, the ground is still connected to the ground buss.

[joe milana]

Jim, that's how I have it connected. I used 12/2 w/ground between my receptacle and sub panel. The black and white for L1 & L2 and the bare ground wire to the ground bus.

However, on a 30A recepticle for an electric heater, I used 10/3 w/ground using black and red for L1 & L2 and the white for the ground and ran it to the neutral bus. I left the bare wire unused. Is this incorrect?

[Rob Lineman]

Black and red are OK, white could be used as a ground since you've already got it connected at the receptacle (change it in the panel), but I would change that to the bare wire and leave the white disconnected. DO NOT CONNECT TO THE NEUTRAL BUS.

[joe milana]

The bare wire in the 10/3 is only 12 gauge. The ground wire from the main panel to the sub is only #12. Is this OK?

Why do household appliances like Dryer and Range use a white wire of same gauge as the red and black and connect to the neutral bus?

[Jim Becker]

Despite the fact that the neutral wire terminates in the same effective place in the MAIN panel, it's still a different connection than the ground. If you were connecting to a sub-panel, the ground and neutral buses are not bonded in that panel. Dryers and some other appliances have the neutral because they likely support a 120v function, such as a clock, timer or light. There would be a four conductor receptacle in that case. The neutral carries current in 120v circuits. Our 240v power tools don't need that. The correct connection in a three conductor 240 receptacle is two hots and one ground.

[Rob Lineman]

the ground wire can typically always be smaller than the voltage conductors and usually are in manufactured multi-conductor cable to save copper and space. the 10/3 conductor has a full size neutral included in the construction for a 240 v/ 3 wire configuration. in some instances, due to voltage drop concerns, you could run a 220 v/3 wire circuit to a series of 120 v receptacles, alternating connections between a phase conductor and neutral at each receptacle as long as the total calculated receptacle load did not exceed 1,900 vA on the phase to neutral connections on each phase conductor. this would allow you to run upwards of 18 receptacles on a 20 a, 2p breaker as long as the the total distance was around +/- 120', on a single phase circuit this is distance is only about 65 to 70'. a common practice in industrial applications. another use for a 3 wire connection would be a piece of equipment that had a 120 volt sub component that needed power and has no internal CPT.

BTW Becker's answer is just as good and a whole lot less technical

[joe milana]

So when wiring a 220 receptacle for power tools, does the ground wire have to be the same gauge as the "hots" ie. use x/3 and use the white for ground, or use x/2 with ground and use the bare wire. (typically the ground wire is a smaller gauge in larger gauge wire i see available)

Also, I used 6/3 nmc with ground from main panel to sub. The ground wire in the 6/3 is only 12 gauge. I am thinking I should have used something different with a larger ground wire.

[Rollie Meyers]

the ground wire can typically always be smaller than the voltage conductors

That only applies in cables 8 AWG & larger and rarely applies to flexable cords 10 AWG & smaller require grounding conductors the same size as the ungrounded & grounded conductors, flexable cords mostly have all conductors the same size.


On another note if one were to increase the size of the ungrounded conductors("hots") the equipment grounding conductors must be increased in size proportionately per NEC 2005 section 250.122 (B),which means for example, if one were to run 8 AWG for a 30 A circuit the equipment grounding would have to be 8 AWG even though 10 AWG is permitted for #6 & 8 AWG. This is off topic for the subject at hand but is something to considered when upsizing wiring, it will mean that NM 'Romex®" cables would not be allowed, as the ECG is 10 AWG.

[joe milana]

Rollie, are you saying I should have run a #6 ground wire from my main panel to my sub instead of using romex?

[Rollie Meyers]

Rollie, are you saying I should have run a #6 ground wire from my main panel to my sub instead of using romex?

If it a 50 A w/ 6/3 NM it's fine w/ the 10 AWG ECG. Only if upsizing conductors for voltage drop does that code section come into play. Sorry if I confused you.

[joe milana]

So my final conclusion is that EVERY 3 conductor 220 outlet wired to my subpanel gets the third conductor wired to the GROUND bus and not the neutral bus?!?! (which yes, is unbonded)

Thanks!!!

[Tom Veatch]

...
Why do household appliances like Dryer and Range use a white wire of same gauge as the red and black and connect to the neutral bus?

Because those appliances require both 120 and 240 volt supplies. 240v is used for the heating elements, 120v is used for the timers, lights, etc.

The voltage between the red and black is 240v. The voltage between either red or black to the white neutral wire is 120. You don't need the neutral unless you need 120 volts.

[Bill Houghton]

So my final conclusion is that EVERY 3 conductor 220 outlet wired to my subpanel gets the third conductor wired to the GROUND bus and not the neutral bus?!?! (which yes, is unbonded)

If your outlets have three holes into which the plug goes, one of them should be the equipment ground. The terminal screw for this hole may be tinted green, or not; if I recall correctly, the equipment ground lug on the plug will usually be a kind of "U" shape, with the hole in the outlet being a matching shape. This goes to the ground bus. The bare or green wire in the set of wires from the panel to the outlet should be used for this connection.

Never wire up a piece of shop equipment without an equipment ground, unless it's double-insulated. I have never seen a double-insulated 220V tool - don't know if there are any. The double-insulated tools I have seen are all small 110V hand held tools (drills, for instance).

[Bob Slater]

Just curious how you would wire the neutral on a three wire plus ground cable? I have one of these that goes more or less to where I want my 220V dust collector. Would that leave an extra wire to run a seperate 110 outlet? If yes, what would the neutral wire be?

[joe milana]

Tom, the only outlet in question now is a 30A for a Dayton heater (which I don't have the manual for). I'm wondering is the element 220v and the fan 110v which would require the neutral wire.

[Tom Veatch]

Tom, the only outlet in question now is a 30A for a Dayton heater (which I don't have the manual for). I'm wondering is the element 220v and the fan 110v which would require the neutral wire.

Can't say for sure. I believe "Dayton" is the house brand for Grainger, so you might could check with them to verify the electrical requirements.

If it's a portable heater and the power cord and plug is intact, you should be able to tell from the plug configuration. Google "NEMA Blade Chart" and match the configuration to those shown. If it's a 250/125 dual voltage plug, NEMA 10 or 14 series, then you'd need a neutral and two hots in the circuit.

If the plug isn't available, the number of wires in the power cord would be a clue. If one of them is grounded at the heater end and there are 3 additional wires in the cord - total of 4 wires in the cord - then it's a dual voltage device and needs a neutral. If there are only 2 wires in addition to the ground wire, it could be either a 120v or a 240v device. If you're sure it's 240 then you don't need a neutral.

[Tom Veatch]

Just curious how you would wire the neutral on a three wire plus ground cable? I have one of these that goes more or less to where I want my 220V dust collector. Would that leave an extra wire to run a seperate 110 outlet? If yes, what would the neutral wire be?

All the 3 + ground NMC cables I've seen have a bare, white, red, and black wire. At the breaker box, the red and black are connected to opposite poles of a 240v breaker, the white to the neutral bus, and the bare to the ground bus.

To get 120v at an outlet, you use the neutral white and either one of the black or red wires. To get 240, you use only the red and black. In either case, the bare is used as the grounding conductor.

[joe milana]

Tom, it's a NEMA 6-30P Plug. Sounds like a two pole grounded circuit.

[Tom Veatch]

Tom, it's a NEMA 6-30P Plug. Sounds like a two pole grounded circuit.

If the plug is a NEMA 6-30, then the receptacle should also be a 6-30 and be wired with the bare to the ground connection, "G" in the NEMA diagram, and the red and black wires to the other two connections. The NEMA chart may either show them as "X" and "Y" or as unlabled. It doesn't matter which color goes to which of those two connections. The white neutral isn't used. If there are no unusual conditions and the one-way cable run is less than about 65 feet for 2% voltage drop or 160 feet for 5% voltage drop, the wire should be no smaller than 10AWG, and the breaker must be a 30A breaker.

If the circuit is wired with individual insulated wires instead of NMC, any colors other than white or green may be used for the hot wires although black and red are probably the most common. White is reserved for use only as the neutral or grounded conductor. Likewise, green is reserved for use only as the grounding conductor.

[Rob Russell]

I believe "Dayton" is the house brand for Grainger ...

Dayton is a national manufacturer of high quality motors and other "electrical stuff". They're not a Grainger "house brand" (like Craftsman is for Sears), but Grainger does carry a lot of Dayton equipment because it's generally industrial/hard use quality. Dayton equipment is also generally on the mid to upper end of the price spectrum, at least the things I had looked at were when I was buying that sort of stuff from the local Graingers.

[joe milana]

Tom, I'm about 10' total to breaker box, #10 wire, NEMA 6-30P Plug, NEMA 6-30P receptacle, red-black to 30a breaker, bare to ground lug Sounds like I am wired correct and good to go..just in time...It's 28 degrees here in KC this morning!
Sure appreciate the help.

-Joe

P.S. The bad news is I hear these heaters are good for about 2-3 seasons, then "shoot craps"

[Tom Veatch]

Dayton is a national manufacturer of high quality motors and other "electrical stuff". They're not a Grainger "house brand" (like Craftsman is for Sears), ...

Rob,

Please understand that my use of the term "house brand" in reference to the Dayton brand was not intended to denigrate the product in any way. I've not seen the brand anywhere except at Grainger so my intent was to direct the OP to Grainger for any additional information.

Your comment did spark my interest so I did a quick Google search on "Dayton motor" and found that in at least one instance (http://www.cpsc.gov/cpscpub/prerel/prhtml01/01504.html) Emerson Motor issued a recall for some models of Dayton branded motors. That implies, at least in Dec. 2000, that Emerson was responsible for a Dayton branded product presumably through either original manufacture or by merger. Maybe it's a coincidence, but an Emerson company was a supplier for some of the older and more highly regarded Craftsman branded power tools.

None of this contradicts, nor is it intended to contradict, anything you said about the reputation or quality of Dayton branded products.