Too many wires?

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  #1  
Old 02-02-13, 03:10 PM
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Too many wires?

I am trying to reinstall a small 220 volt baseboard heater in a bathroom. I have a new dimplex 500 watt linear convector baseboard unit and the original Federal 2 pole thermostat. I want to use the existing wiring, which is still in place, though the double pole 30 amp breaker is not hooked up yet. It hasn't been used since I took the old baseboard out when we went to hot air heat. The odd thing is that there are 3 peices of 12/2 with ground coming into the thermostat junction box on the wall. one set goes to the baseboard, the other 2 have their whites, blacks and bare grounds twisted together with a single lead coming from the whites wire nut and the blacks nut. What could the extra piece of Romex be for? There was once baseboard heat in each room. I'd like to figure out which piece goes straight to the breaker box with my continuity tester and just disconnect then odd piece of Romex. What do you think it was for? There was once a heater in the kick board under the kitchen sink which is near by. Could it have been hooked up to this extra piece of Romex? thanks, Kirby
 
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Old 02-02-13, 03:15 PM
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A picture might help us help you. http://www.doityourself.com/forum/li...-pictures.html
 
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Old 02-02-13, 05:25 PM
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I'd like to figure out which piece goes straight to the breaker box with my continuity tester and just disconnect then odd piece of Romex. What do you think it was for?
500 watts is nowhere close to the capacity of a 30 amp circuit. The circuit probably not only fed this baseboard heater, but fed through this box to one or more other baseboard heaters in other rooms.

The odd thing is that there are 3 peices of 12/2 with ground coming into the thermostat junction box on the wall. one set goes to the baseboard, the other 2 have their whites, blacks and bare grounds twisted together with a single lead coming from the whites wire nut and the blacks nut.
the double pole 30 amp breaker is not hooked up yet
Your 30 amp breaker will also need to be changed to a 20 amp breaker.
 

Last edited by CasualJoe; 02-02-13 at 06:11 PM.
  #4  
Old 02-02-13, 05:40 PM
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My guess is there were at least 3 heaters connected in that circuit. The short pigtails coming out of the wire nuts that connected the 2 sets of wires together was probably connected with wire nuts to the third 12/2 and the heater.

I would connect the wires at the breaker with it in the off position. Next carefully remove all the wire nuts and test all wires to be sure they are dead then separate all the wires. Have someone flip the breaker on and test to see which set of 3 wires is hot.

That's the lazy way. If you're not comfortable poking around wires that are hot with your meter then separate the wires as above and test for current before handling them and use your continuity tester. You'll need a length of wire that reaches from the breaker panel to the wires in the bathroom. Connect it to either the black or white wire that would go to the breaker, then in the bathroom test for continuity between the other end of your jumper wire to each of the same color wire in each of the 3 sets of 12/2.

I would wire nut and tape the other 2 sets of wires, at both ends if you can find them. You just never know......especially if they run through inaccessable areas. You wouldn't believe some of the crazy stuff I found in my place that the previous owner did with wiring.
 
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Old 02-02-13, 07:52 PM
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The odd thing is that there are 3 peices of 12/2 with ground coming into the thermostat junction box on the wall. one set goes to the baseboard, the other 2 have their whites, blacks and bare grounds twisted together with a single lead coming from the whites wire nut and the blacks nut... There was once a heater in the kick board under the kitchen sink which is near by. Could it have been hooked up to this extra piece of Romex?
Yes. The black and white pigtails connected the thermostat to power.

Bend the set of wires going to the baseboard heated in the bathroom out of the way. Undo the black and white splices, discard the pigtails and push each wire aside at a different angle. Change the breaker to a 2-pole 20A breaker, as Joe suggested - because you said the wire is #12 AWG - and turn it on. Test between the black and the white in each cable to see which pair shows 240V, as Crispy suggested. The pair that shows 240 is your power feed.

Kill the power, cap the wires in the unneeded cable, and attach your new thermostat to the wires in the power and load cables.
 
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