I am installing a new 20amp 250v circuit in my garage to run a table saw. I am using NMC 12/3.
I have clear instructions,pictures etc on how to wire up the new breaker in the panel and the new plug to the saw’s power cord. I also have detailed instructions from Delta on how to re-configure the wires inside the motor housing (the motor has 1.5 and 2.0 capacity).
The area of uncertainty is inside the new (metal) box where the NMC with four wires meets the receptacle which has only three connecting points (2 copper or brass screws I’m not sure which but they are not silver in color so I assume they are for the two hot wires and one green screw I assume is for the grounding screw).
My question is: can anyone point me to a publication that has a picture or diagram that shows the position/connection of the 4 wires coming into the metal box and meeting up there with the 3 position receptacle.
I have a copy of “Wiring Simplified” which is very good but limits its discussion to 3 wire cable (black,white and bare copper).
P.S. I do know about “Pigtails” and think they are involved here but am not ABSOLUTELY sure just how.
Thanks in advance for any responses.
Edited 2/8/2003 3:36:10 PM ET by MikeE
Replies
You only require the two "hot" conductors and the ground. The white "neutral" is only necessary if you are intending to split the 220 for 110 as in a cloths dryer application. The neutral white wire in the 12/3 is unnecessary.
Cheers,
Brent
Edited 2/8/2003 5:02:22 PM ET by BHORNICK
Great info.
Many thanks for the feedback
Hi Brent and Mike,
I just wired my new Unisaw circut saturday, Used EMT, #12 wire, 20amp circut breaker, very easy. Used the same instructions your getting here.
Happy sawing,
Dick
I feel much more comfortable now with AWG 12/2 and have everything laid out on paper and in my head. Will actually do the work as soon as I feel up to giving the Delta saw a good tune-up.
If you get a chance, let me know if your senses note any change/improvement in your saw's performance.
Thanks for the feedback.
Mike
Here's a link to a plain-vanilla 240V saw-type circuit. Notice the red stripe on the white conductor; it's hot, and would be taped black or red in real life. Since you already have the 3-wire w/ ground, simply coil up the white neatly, wirenutting each end to prevent accidental contact with anything hot, and use the black, red, and bare ground.
When you're done, check each slot (one 'tee' and one straight, if it's 20A) to ground; should read 120V or thereabouts. Hot to hot should read 240V.
But if you really don't feel comfortable doing this, pay an electrician for the hour (including coffee break and lunch) it will take him/her to make the connections after you've run the cable. Since you're only powering one receptacle (my assumption), you don't need to pigtail anything except the ground.
Edit: Yikes! I forgot the link! http://www.danswiringpage.com/diagrams/220_ac.jpg
Be seeing you...
Edited 2/8/2003 9:08:51 PM ET by Tom Kanzler
Many thanks for the feedback.
Regards,
Mike
MikeE - I added the missing link (no, not my BIL) to my post above. Here it is again.
http://www.danswiringpage.com/diagrams/220_ac.jpgBe seeing you...
Thanks a lot for the info. I just tried to go on there but it was "currently unavailable".
That site had been mentioned earlier by someone and I have been on it and got some info and copies of wiring diagrams which are now lodged out in my file folder in the shop. I'll marry up this your latest post with the previous material and come back to you if I have any further questions.
At the moment, everything is quite clear except which cable to use. If I use AWG 12/2 then I am home free. If I use AWG 12/3 then I have the extra insulated wire (the white neutral one) which the consensus seems to be should simply be capped off at both ends which opens the question of why use 12/3 (with 3 insulated wires and a bare ground) in the first place.
I have 2 books including "Wiring Simplified" and a file of copies of many of the posts I received. I am almost there. Many thanks for all your help.
Regards,
Mike
There is no need for 12-3, but if you have it then you might keep it for future use.
Some people like to run everything as 120/240 circuits for shop use. And run it through to the equipment.
That is so that they can add an 120 volt light or 120 feeder.
But most people don't do that. For the rare times that they need that they have a separate cord to a 120 outlet.
If you are wiring the circuit for use as a 20 amp supply 220 volt for your table saw then just use 12/2. The white wire needs to be then marked as a "hot" conductor. Color it black with perminent marker where it enters the service panel and the table saw supply box. You can also wrap it in black electrical tape although i'v seen this fail after a few years if not put on securley.
Running the 12/3 with the neutral white is normally used if you were running a split recepticle or to a device that used both 220 and 110. Things like a dryer use the 220 for the heating coils and the 120 is for the control circuit to reduce cost, make things smaller and safer.
Run your cable as 12/2, color the white line black and use the supply to solely power the table saw. If you tap off to run lights etc. You can cause problems with the table saw motor bogging down and you may overload the 20 amp breaker causing it to trip. Cheers,
Brent
More properly, you should color the white conductor red rather than black, since it is the second hot conductor, and is also from the opposite pole from the first (black) conductor. They sell paks of multicolor marking tape just for this purpose.
I don't realy think red or black matters provided it is not white. Cheers,
Brent
Great minds. I recently bought exactly such a pack.
Many thanks.
Great i info.
Many thanks.
Regards,
Mike
I did buy the 12/3 cable but am rapidly becoming convinced that saving it for another may be best. I have plenty of 20amp 120v outlets around the shop so the only thing I would ever run on this circuit would be the reconfigured 220v table saw or something similar I might pick up along the way.
Many thanks for your response.
Regards,
Mike
Edited 2/9/2003 11:51:03 PM ET by MikeE
That was probably me, on another thread. That site seems to come and go. Keep trying, as the page I've linked to has a very nice graphic of your situation, white wire marked as hot and everything. Be seeing you...
Tom:
Thanks again for all the great help.
Regards,
Mike