Got a new toy and need to plug it in. The tablesaw came with a 220v 3 prong 20amp. plug. I got the correct wall outlet for it. My ? is 2 different opinions I’ve received on wiring it. I’m using a sub panel, so my neutral and ground bars are NOT connected. I put in a 20 amp 2 pole breaker (ie for 220 v, spans both buss bars). I wired it with 12-2 wire (also contains a bare ground in the romex). Ran the black & white wires from the breaker (both hot, 1 off each part of the breaker) to the 2 slots on the plug and the bare copper from the grounding bar in the panel to a connector in the box with a pigtail to a grounding screw in the the metal box, and another to the grounding screw on the outlet. (Takes as long to describe it as to do it!!)
A contractor friend told me this is wrong, that I need to run 12-3 wire, with the black and red as hot, the white from the neutral bar to the grounding part of the plug, and the bare copper from the grounding bar to the metal box. He claimed the neutral was needed as the return loop for the alternating current.
What do you think & why?
Replies
Call an electrician and have him/her wire it for you. If something goes wrong you at least have a recourse. Chances are you will get the right answer here and in fact I know it but I'm not an electrician and would not want the responsibility of you possibly missunderstanding something that I said or recommended here.
By the way he's partially right and partially wrong. The electrician you hire will do it right.
1st-matter of quality. 12-3 w/ a red and black conduct is the right way to do it, particularly if anyone ever looks at your work. Here the system neutral on the power poles are ran down to earth every so often off the utility's grid. The neutral though does run all the way back on the utility grid. So in effect neutral and ground on your bus bar are the same thing. I'm not an electrician either. My understanding is that the purpose of the neutral is to take the return current, the ground handles surges, although both carry some degree of the return. Anyway I know code is black or red for your live wire, white for neutral, copper for ground, so that's how I wire things when the occasion befalls me. I also try to hook them to the right sides of the receptacle, i.e. brass screws to hot and silver screws to neutral.
remodeler
Jim, your are fine the way you wired it. On a straight 220v motor you don't need a nuetral (white wire), you do need the equipment ground (bare or green wire). The only thing you might add is a marking tape of black or red color to both ends of the white wire. This indicates to anyone else, and reminds you, that the white wire is a hot wire.
FYI nuetral wires are current carrying conductors, should be white or gray color, and respected as potential shock hazards.
Dave
As Dave said you are perfectly correct. Just remark the white wire with tape.
For those who think that you need a neutral what would you connect it to? The plug and socket only have 2 hot connects and the ground.
For 240/120 volt service the power is supplied from a transformer. The secondard of the transformer is center tapped so that you have 120 volts from the center tap to eithr hot. The center tap is the neutral. You only have current flowing in it when you have unbalanced 120 volt loads.
For 240 volt loads they are connected to the two hots and no current flows through the neutral.
Thanks one and all for the feedback. I already marked the white wire with black tape and actually figured I had it done right, but wanted some reassurance. Again thanks, now to get cuttin' some wood and making furniture & some $$.