Question for the home electricians

[George Carion]

Getting my 3HP PM2000 next Monday (yea me). However, like many people with their first 230v tool, I lack the appropriate power in my garage. My 230v 30 amp dryer outlet is unused and exactly on the other side of the wall where the new TS will be placed. Eventually I'll have a sub-panel installed in the garage, but for now I'd just like to turn the dryer outlet around.

I've got two questions about this. The first is, am I going to burn my house down? :D

Second, I was expecting 4 wires going to this outlet including a ground. I've got 3. No ground. IS THAT NORMAL?

Thanks!

[Carl Crout]

Shouldn't be a problem other than the fact that you will have to buy an outlet the match the plug on your tool.
220V outlets usually only have three wires, 2 hots and a neutral.
Your tool may only call for a 20A circuit, in that case you may want to change the breaker to a 20A one.

[Bruce Shiverdecker]

Evening George.

Re: 4 Wires. I would think that the Neutral is the missing wire as it is not needed for 2 phase (Standard Household Wiring) 230Volt is two phases and a GROUND, not a neutral. If you take a volt meter between either "HOT" leg and the ground, it shows 120 Volts; between the two Hots it is 240V.

Moving the outlet to the other side of the wall should't cause any fire problems.

Bruce

[Tom Cowie]

Evening George.

Re: 4 Wires. I would think that the Neutral is the missing wire as it is not needed for 2 phase (Standard Household Wiring) 230Volt is two phases and a GROUND, not a neutral. If you take a volt meter between either "HOT" leg and the ground, it shows 120 Volts; between the two Hots it is 240V.

Moving the outlet to the other side of the wall should't cause any fire problems.

Bruce

Ditto To what Bruce said. No neutral on a 240 circuit only a dedicated ground. Moving to a new location should be OK if you do it correctly ( Junction box and correct wire size )
Congrats on the new tool . Very nice saw.

Tom

[Rick Christopherson]

Your NEMA 10-30R receptacle is no longer code compliant for your dryer, but still grandfathered in and acceptable, so long as you don't work on the circuit. Once you work on that circuit, then you must convert it to 240-volt, grounded, without neutral, which is what you need anyway.

Using it for your tablesaw is just fine, because you do not need both a neutral and a ground, just a ground. As long as this is being fed from a main load center versus a subpanel, then you are OK. If it is a subpanel, where the ground and neutral are isolated, then you need to make sure this wire gets moved from the neutral bus to the ground bus in the panel.

Under normal circumstances, the ground and neutral are not the same, but in order to answer your question, they must be treated as being the same, unless it comes from a subpanel. For this reason, I caution other readers of this discussion to not draw erroneous conclusions from these instructions.

Go ahead and rewire the outlet with the two hots and the ground into your shop. To be properly code compliant, you should use a different outlet, such as a NEMA 6-30 instead of your NEMA 10-30.

P.S. When I started this response, there were no replies yet...oops. By the way to those other respondents, yes, the NEMA 10-30 receptacle uses a neutral but no ground. This is the reason for the comments I made above.

[George Carion]

Your NEMA 10-30R receptacle is no longer code compliant for your dryer, but still grandfathered in and acceptable, so long as you don't work on the circuit. Once you work on that circuit, then you must convert it to 240-volt, grounded, without neutral, which is what you need anyway.

My home is about 8 years old. The outlet is NEMA 10-30. It's no longer spec? I'm a bit confused by your reply (i'm slow). Is the 3rd wire neutral or ground? It looks like 10 gauge wiring. Should I keep the configuration the same, but change the outlet to a NEMA 6-30?

Thanks guys!

[Jim Becker]

George, what Rick is effectively saying is that the current outlet is not code compliant for new installs or if you make changes to the circuit...the latter being your specific case. Code does evolve and apparently has since your home was built. What you need to do is:

1) See how the three conductors for that circuit are landed in your panel. If it's to the main panel where the ground and neutral buses are bonded, you don't have to change the third (non-hot) conductor's position over from the neutral bus to the ground bus, although you are certainly fine to do so. If this circuit goes to a sub-panel, you must change the third conductor over to the ground bus.

2) install a new outlet plug of appropriate type to service your saw on the end of the wire. If that location isn't correct and you need to splice in more wire to get where you need to go, use a junction box to house the splice at the old outlet location, making sure that the cover on the j-box is accessible for future maintenance. Be sure that any new wire is properly routed/protected.

Obviously all of this should be done with the power turned off... ;) ...and if you're not sure about the panel stuff, at least get some advice from a licensed electrician relative to how the third conductor is situation for that circuit.

[Chris Rosenberger]

The dryer outlet is no longer in spec because the code now requires ground & neutral wires to be connected to a dryer & also ranges. Some componets in dryers and ranges are 120 volt & need a neutral & ground to not present a shock hazard.

[George Carion]

This circuit is wired back to my main panel so it looks like I'm good. I'm not going to need to extend the circuit. I'm literally just cutting a hole in the other side of the wall and installing a new box and outlet.

I love this forum. Thanks again.

[Mike Henderson]

Evening George.

Re: 4 Wires. I would think that the Neutral is the missing wire as it is not needed for 2 phase (Standard Household Wiring) 230Volt is two phases and a GROUND, not a neutral. If you take a volt meter between either "HOT" leg and the ground, it shows 120 Volts; between the two Hots it is 240V.

Moving the outlet to the other side of the wall should't cause any fire problems.

Bruce
I don't want to get too picky here, but household power is single phase, whether it's 120V or 240V. There's really no two phase power in the grid any more although there was at one time long ago (before three phase power). You can check this article (http://en.wikipedia.org/wiki/Two_phase) at Wikipedia.

Mike

[David DeCristoforo]

I am not saying this is the way to go but the easiest thing would be to just put a dryer plug on the TS. That way you don't have to mess with the house wiring at all. Some years back I had a small shop set up in the garage of a rented house and that's how I did it and it worked fine. I also had to put longer cord on the TS to reach. Later on when you re-wire your new sub panel, you can change the plug out for a newer one.

[Rick Christopherson]

This circuit is wired back to my main panel so it looks like I'm good. I'm not going to need to extend the circuit. I'm literally just cutting a hole in the other side of the wall and installing a new box and outlet. It sounds like you are good-to-go then. By the way, this is not the end of the world if you don't do it, but it would be a good idea (and code) to re-identify the previously-neutral wire as a ground (grounding conductor) by coloring the ends green, assuming the wire is already white. If the wire is green or uninsulated copper, then this isn't necessary. But, regardless what code says, it's not a big deal if you don't.

[Joe Jensen]

I am not saying this is the way to go but the easiest thing would be to just put a dryer plug on the TS. That way you don't have to mess with the house wiring at all. Some years back I had a small shop set up in the garage of a rented house and that's how I did it and it worked fine. I also had to put longer cord on the TS to reach. Later on when you re-wire your new sub panel, you can change the plug out for a newer one.

I agree with David. In the end, you need a dryer outlet to sell the house. You say the situation is temporary. I'd leave the dryer outlet alone, and put a dryer plug on the saw. If need be, drill a couple holes in the wall to run the cord through. Maybe a small doggy door? Drywall is easy to patch when you get the sub panel in the garage...joe

[Jim Becker]

By the way, this is not the end of the world if you don't do it, but it would be a good idea (and code) to re-identify the previously-neutral wire as a ground (grounding conductor) by coloring the ends green, assuming the wire is already white. If the wire is green or uninsulated copper, then this isn't necessary. But, regardless what code says, it's not a big deal if you don't.

This is excellent advice...we always need to remember that "we" may not be the next person working on that wire. Remarking is a good practice for safety as well as practicality. (Same goes for identifying "hot" conductors on a 240v circuit where a white wire is involved)

[Randall Davis]

I don't want to get too picky here, but household power is single phase, whether it's 120V or 240V. There's really no two phase power in the grid any more although there was at one time long ago (before three phase power). You can check this article (http://en.wikipedia.org/wiki/Two_phase) at Wikipedia.

Mike

mike is correct single phase, and in some situations a nutral wire is required (kitchen ranges, dryers and others) the neutral in this type of circuit would be used for the 120 volt loads within the appliances (timers, clocks, igniters etc.) that being said the OP does not need a nutraul in his situation the existing 3 wire circuit will be fine. the circuit breaker is ment to protect the circuit it self not the equipment being pluged in to it so the existing breaker should be ok just mate the outlet and cord and you are in busness.

[Jim Heffner]

George, that dryer outlet that you have a question about is perfectly safe
and could be converted for use to your new saw. The dryer outlet has
3 wires in it...2 hot wires and a neutral. The neutral is a grounded conductor. The newer outlets have 4 wires....2 hot conductors, a neutral
( grounded conductor) and a bare or green wire that is an equipment
ground. I know this can be confusing, it was to me for a while when I first
started doing electrical work. The grounded conductor ( neutral) is merely a electrical return path for current, the grounding conductor (green or bare wire) is for equipment short circuit ground path. All electrical service
that is in use currently in homes and small business is 240 volt single phase, large, commercial, or industrial users have three phase service
installed there. You will have to install the proper outlet that matches the cord on your saw, and change the fuse or breaker for it also.
Don't worry about the wire size being too large for the breaker, that is ok.
The code says that you can UNDER fuse (reduce) the breaker size but NEVER overfuse it, that is to say that a # 10 AWG wire size is good for 30
amp fuse/ breaker, it can be used like a #12 AWG wire and fuse it for 20 amps if needed, no problem. Hope this helps clear it up for you...
Jim Heffner

[Brian Weick]

I don't want to get too picky here, but household power is single phase, whether it's 120V or 240V. There's really no two phase power in the grid any more although there was at one time long ago (before three phase power). You can check this article (http://en.wikipedia.org/wiki/Two_phase) at Wikipedia.

Mike
Dito Mike - 3 phase (220) has 4 / 1 being the ground , single hase (220) 2 hot and 1 ground - Mike's the man!