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 DIY Chatroom Home Improvement Forum Is it 120V or 240V?
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05-08-2011, 09:07 AM   #1
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Is it 120V or 240V?

A couple of years ago I removed a baseboard heater from my basement. Now I am making a workshop in my basement for my hobbies and need a couple of outlets. The electrical line is still there from the heater. First, how do I determine if it is a 120V or a 240V line? Then if it is a 120V line, how many outlets can I run from that line?

05-08-2011, 09:13 AM   #2

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Check where it's attached to the breaker. A 240v circuit will have both wires connected to a double pole breaker. A 120v circuit will have the black hot wire attached to a breaker, and the white neutral attached to the neutral bar.

You can put as many outlets as you want on a circuit, unless you're in Canada, in which case you're limited to 12.

If it is a 240v circuit, you can simply replace the breaker with a single pole, and move the white wire to the neutral bar to make it a 120v circuit. If the wire is 14-gauge, use a 15A breaker. If 12 gauge, you can use a 20A.

 05-08-2011, 10:58 AM #3 Newbie   Join Date: May 2011 Posts: 4 Rewards Points: 10 How do I know if it is 12 gauge or 14 gauge? Now i have to go and trace the wire to see what breaker it is hooked to.

05-08-2011, 12:12 PM   #4
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Quote:
 Originally Posted by scooter67 How do I know if it is 12 gauge or 14 gauge? Now i have to go and trace the wire to see what breaker it is hooked to.
If the walls are open, and you can see the cables coming into the panel, look at where the cable (if it is Romex) comes in. The cable should have the guage (such as 14/2 or 12/2) stamped on the sheath of the cable.

If that's not possible, then replace the single pole with the same amperage as was the double pole.

05-08-2011, 12:26 PM   #5
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Quote:
 Originally Posted by sirsparksalot If the walls are open, and you can see the cables coming into the panel, look at where the cable (if it is Romex) comes in. The cable should have the guage (such as 14/2 or 12/2) stamped on the sheath of the cable. If that's not possible, then replace the single pole with the same amperage as was the double pole.

Not a good idea, the existing breaker may be wrong for the wire size. Get a wire stripper with wire gauge markings and measure it.
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05-09-2011, 07:50 PM   #6
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Quote:
 Originally Posted by sirsparksalot If the walls are open, and you can see the cables coming into the panel, look at where the cable (if it is Romex) comes in. The cable should have the guage (such as 14/2 or 12/2) stamped on the sheath of the cable. If that's not possible, then replace the single pole with the same amperage as was the double pole.
I had my wife flip breakers while I held a circuit tester on it. The cable has a three wire Hot, Neutral, and Ground. The breaker is a double pole breaker. I can just replace the breaker with a single breaker correct? Then I should be at the 120V I need, right?

05-09-2011, 08:24 PM   #7

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Quote:
 Originally Posted by scooter67 I had my wife flip breakers while I held a circuit tester on it. The cable has a three wire Hot, Neutral, and Ground. The breaker is a double pole breaker. I can just replace the breaker with a single breaker correct? Then I should be at the 120V I need, right?
You still need to move the white from the double pole breaker to the neutral buss. You also need to install a breaker blank to close off the unused opening.

BTW, with 240 you do not have a neutral. You would have two hots and a grounding conductor.
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Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.

 05-09-2011, 08:55 PM #8 Electrician   Join Date: Nov 2005 Location: Winnipeg, Manitoba Posts: 1,298 Rewards Points: 802 You could also take the white off the 2 pole breaker and put it to the neutral bar. Leave the black on the 2 pole breaker and use that breaker if it is the right amperage. I don't beleive this violates any codes but if I am wrong someone will correct me.
05-10-2011, 08:43 AM   #9
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Quote:
 Originally Posted by Jim Port You still need to move the white from the double pole breaker to the neutral buss. You also need to install a breaker blank to close off the unused opening. BTW, with 240 you do not have a neutral. You would have two hots and a grounding conductor.
The one thing I did not check was to see if the other white was actually a hot line. I was thinking it was either a neutral or ground but thinking about it, neutral is technically a ground. I am good with small simple circuits not house wiring. I am not sure I can do this myself now. My need to call a professional. So much for saving money on something that is probably simple.

 05-10-2011, 08:51 AM #10 Just call me Andrew   Join Date: Mar 2009 Location: Albany, NY Posts: 2,265 Rewards Points: 1,020 Did your circuit tester read 240v from black to white? If so, both lines (black & white) are hot. What amperage is the double-pole breaker that controls this circuit? What you're trying to do is pretty simple, and as long as you are comfortable working inside your panel, you can do this yourself. If you are not, then call an electrician. __________________ Andrew
05-10-2011, 08:52 AM   #11

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If it is indeed a 240v circuit, then no, the white is not a neutral. Black and white in the cable are both being used as hots, with 240v between them. In the breaker panel, you should see that black and white are both connected to the double pole breaker. This is what everyone is talking about; the white wire simply needs to be moved to the neutral terminal bar in the breaker panel. This will make it a 120v circuit.

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