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Forum topic by Jeremy Greiner posted 162 days ago 1185 views 1 time favorited 35 replies Add to Favorites Watch
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Jeremy Greiner

567 posts in 1277 days


162 days ago

I got the subpanel added to the basement, but I was fairly confident in my ability to actually do the wiring myself. I went to homedepot to get the materials I needed, breakers, boxes conduit etc..

The person there, said that I needed 12/3 wire instead of 12/2 because I’m wiring into a subpanel. I hadn’t heard that, but alas that’s what I got. Now I’ve done some research and now I feel I’ve gotten the wrong wire and I should have gotten a 12/2 instead.

As a note, I plan to use the wire for a 20amp 220v outlet (and a separate 110v chain of outlets).

Am I hosed? I already cut the wire so I don’t know if they’ll take it back, if I am supposed to use the 12/3 wire I’m not sure what I’m supposed to do with the extra red wire. The youtube video’s I watched to prep for this where using 12/2 wires.

-jeremy

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html


35 replies so far

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Redoak49

144 posts in 494 days


#1 posted 162 days ago

I am certain that there are a number of threads on this. 12/3 is correct with two hots(back and red) a neutral and separate ground in the sub panel.

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crank49

3249 posts in 1476 days


#2 posted 162 days ago

If you are connecting a 220 volt outlet the black and the red wires are the hot leads.

The spare wire might either be white or green, you didn’t say, but which ever color it has to be the ground.

The reason they said you need 12-3 instead of 12-2 is because in a subpanel the ground and neutral (in the case of a 120 volt outlet) have to be isolated from each other and the neutral buss and ground buss are also isolated in a sub-panel. the 12-2 w/gnd wire has a bare wire for the ground. You can’t use that bare wire for the neutral.

There is supposed to be only one place in a system where the neutral and the ground are bonded (tied together) and that is in the main breaker panel.

-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.

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hjt

765 posts in 1644 days


#3 posted 162 days ago

Sounds like Crank has done some of this in the pass. Check out youtube as well for info.

-- Harold

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Jeremy Greiner

567 posts in 1277 days


#4 posted 162 days ago

Thanks Crank,
That all makes sense looking at the breaker box and from what I’ve read about the separate ground and neutral bars in the subpanel (and what I see in my subpanel). I guess my confusion came in at the outlet. Since it only had 3 screw connectors (1 hot brass, 1 neutral silver, 1 ground green), do I have to get a special type of outlet? Do I cap one of the hots? or do I put both hots into the hot screw?

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

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Holbs

430 posts in 535 days


#5 posted 162 days ago

jeremy… what is the use of the 20amp 220v outlet? what machinery will you be running and what is the required amperage? i went the safe route and used 10/2 red/black/bare ground wire for all of my 220v outlets.
might want to research 220v outlets and wiring. putting both hots into a single screw = trouble. i researched a good 2 months of cazillions of youtube videos, electrical webpages, electrical remodel, and municipal code BEFORE i even began my electrical remodel of my garage (take a peek at my blog of the matter if it helps).

OH WAIT! did you use 12/2 for the subpanel feed? or just for 220v outlets?

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crank49

3249 posts in 1476 days


#6 posted 162 days ago

Two hot leads, the black and red, make a 230 volt outlet’s power feed and the green screw is the ground.
If you are speaking of a 120 volt outlet, you use a black and a white wire plus a ground.

Back in the breaker box, the black and red wires are connected to the two hot lugs on the 230 volt breaker..
for the 120 volt circuit in the breaker panel the black wire goes to the single hot lug on the 120 volt breaker, the white goes to the neutral buss and the ground wire goes to the ground buss. This assumes you are still talking sub-panel.

#12 AWG wire is good for 20 amps. That’s usually plenty for 230 volt machines. up to about 5 hp induction motors and is just adequate for a 4500 watt 240 volt heater. I’d really feel better with a #10 AWG, 30 amp capacity wire for a 4500 watt 240 volt heater because in low voltage conditions, like under 220 volts, it’s really slightly over loaded by about 1/2 to 3/4 of an amp on #12 wire..

-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.

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Jeremy Greiner

567 posts in 1277 days


#7 posted 162 days ago

@holbs
I have an electrician install the subpanel itself, and 10 awg is good for 30amp, but my jointer requires 15, I put it on a 20amp to be safe, which 12awg is what I read was rated for 20amp.

@Crank
Yes everything is going into a subpanel, so am I correct that both black and red go to the same screw, and the white goes to the neutral and the bare ground goes to the ground screw. (I think that’s what you were saying I just wanted to make sure)

For the 110v I should get 12/2 wire then, and that pretty clears up my confusion :)

-jeremy

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

View Holbs's profile

Holbs

430 posts in 535 days


#8 posted 162 days ago

you used 12/3 for a 220v wood working machine. you have a spare wire that you do not need (the white?). i ran 10/3 for 4 of my 5 220v outlets only because i got a great deal on the 10/3. red goes to one terminal, black goes to another terminal, the bare ground goes to ground screw, the white is un-used.

12/3 or 10/3 is used when you need 220v AND 110v (think of a 220v oven with a 110v clock).
12/2 or 102 is used if purely needing 220v.

doesnt hurt you ran 12/3… you just will not be using one of the wires.
i could be getting the white and bare mixed up… it’s been awhile :)

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Jeremy Greiner

567 posts in 1277 days


#9 posted 162 days ago

@Holbs
It’s my understanding the white is needed to connect to the neutral bar in the subpanel, it seems silly if it doesn’t actually get connected to anything on the outlet end.

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

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Holbs

430 posts in 535 days


#10 posted 162 days ago

http://waterheatertimer.org/images/Inside-Main-Breaker-Box-12.jpg

look at the 10-2 image in the middle. red&black are the 2 hots (both go back to the breaker), the bare wire goes to the ground bar.
this image is of the main breaker panel. a sub-panel is the same for wiring EXCEPT there is no electrical bond piece between the neutral bar and ground bar.

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crank49

3249 posts in 1476 days


#11 posted 162 days ago

NO. Black and Red DO NOT go to the same screw.

A 230 volt circuit has to be attached to a 230 volt breaker.
The 230 volt breaker has two screw lugs where you attach wires.
One wire will be black and goes to one of those screws.
The other wire will be red and goes to the other screw on the breaker.
If your breaker only has one screw it is a 120 volt breaker and can not supply a 230 volt machine.

-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.

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Jeremy Greiner

567 posts in 1277 days


#12 posted 162 days ago

Hi Crank,
Yes I understand that on the breaker, the 2 hots get screwed in seperatly, it has 2 screws that’s not the issue. I’m referring to at the outlet.

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

View Grandpa's profile

Grandpa

2985 posts in 1181 days


#13 posted 162 days ago

modern 220V receptacles have 4 wires and 4 pins on the plugs and 4 places in the receptacle.

View Jeremy Greiner's profile

Jeremy Greiner

567 posts in 1277 days


#14 posted 162 days ago

@Grandpa
My jointer is 3 wire, which I attached to a 3 prong twist lock plug.

I’m trying to wire the 3 prong twist lock outlet and I misspoke is has the 2 brass screws for the 2 hots (on opposite sides) and 1 for the ground. I’m just unsure what to do with the neutral.

My problem may be I have the wrong outlet and I need a 4 prong outlet, and I have to figure out if I can get a 4 prong plug for my 3 wire jointer.

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

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GOOD LUCK TO ALL

418 posts in 233 days


#15 posted 162 days ago


Just don’t use the last wire.

showing 1 through 15 of 35 replies

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