wiring baseboard heaters...please help

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  #1  
Old 08-18-06, 12:03 PM
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wiring baseboard heaters...please help

I am finishing a small room in my garage as a piano/guest room. The room is about 120 sf, and I have a small spot in the entrance way (4') for a baseboard heater, which, at my local Home Depot = 1000 240v. The baseboard heater can be supplemented by a separate electric fireplace for when guests stay, so basically it's just there to keep the piano from freezing.

I'm new to anything non 120v, but have been doing some research, and think I have things figured out. 240 v = two hots, no neutral. Fine, no problem.

The previous owner of my house had a large range style plug wired in this room very close to where I want my baseboard heater. It looks like 3 wire 10 gauge. It was disconnected at the power supply, and taped together, but the breaker spot where it must have gone is TWO 15 amp breakers. He's labeled those "free circuits" (I can't even imagine what he had hooked up to the range plug, given where it is!)

My question is, can I use this existing cabling? I really don't want to have to run new wires when everything is already there, but I will if I have to.

If I can use it, do I use the existing box for the range plug as a closed junction box and run everything from there?

Lastly, if I can't use it, do I use 12/2 wire and buy a single 20 amp breaker to hook everything up? Thank you all for listening to the long winded questions!

Chawkey

edit - now that I look again, the wire may even be thicker than 10 gauge, perhaps 8 or even 6..can't see the casings, so I'm not sure.
 
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  #2  
Old 08-18-06, 12:10 PM
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You need a double pole 15 amp breaker. If the two 15s are a double pole(double full size and both handles tied together for a common trip) you can use them. #14 wire is fine for this. 1000W at 240 volts is only about 4 amps.
 
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Old 08-18-06, 12:13 PM
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Look closely at the wire for this circuit. Is the wiring two insulated conductors and one non-insulated conductor? What color is the insulation of the conductors?

Is 1000 the wattage of the heater?

You need a 240 volt breaker (not two 15 amp breakers) of an appropriate amperage for the wattage and wire size.

If you can reuse this cable, then you would install a junction box where it presently ends (leaving the junction box permanently accessible) and run from there. Don't forget a thermostat, unless the heater includes it's own thermostat.
 
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Old 08-18-06, 12:33 PM
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Wow, I didn't expect to get replies so fast...what a great forum!



Joed - the two 15's are NOT double pole, which is why I am confused/puzzled what he had hooked up here.
There is no #14 wire - it's all at least #10, if not #8 gauge already installed. The question becomes, what size/type breaker do I install, and what size cable do I use for the extentions?

Bob - It is indeed 3 wire (black, red, white, and bare ground). Yes, the heater is only 1000 watts, which I know is not very much, but it's all I have room for in the spot. As I said to Joed, what breaker is appropriate for this setup, and what wire do I use from the junction box?

Thanks for the info on the junction box question!

Chawkey
 
  #5  
Old 08-18-06, 12:43 PM
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You have FOUR wire cable. The bare ground counts as a wire, although under normal operation it is not current carrying. It is also important. Without a ground wire you would need to run new cable.

A 100 watt heater can be connected to a 15 amp or a 20 amp breaker. You need a 240 volt breaker. The setup the previous owner had using two single 15 amp breakers would be for a multi wire setup.

8 gage, 10 gage, 12 gage, or even 14 gage are appropriate for a 15 amp breaker. For a 20 amp breaker you need 12 gage or larger (smaller gage size) wire.

Use the existing red, black, and bare ground. Leave the white wire disconnected at each end, but covered using a wire nut. To extend the circuit use 12 gage wire for a 20 amp breaker or 14 gage wire for a 15 amp circuit.
 
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Old 08-18-06, 01:39 PM
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Again, thank you for the fast reply! I can continue with my reno now. I will purchase a 240v 20 amp breaker in case I want to add another small baseboard heater later.

My bad on the wire count, I assumed because the wire was called 12/2 or 10/3 for example, you always just assumed the ground was there and not counted.

Just for the record, a 240v 20 amp breaker is single pole, right? Forgive my ignorance!

Chawkey
 
  #7  
Old 08-18-06, 02:44 PM
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A 240 volt breaker is a two pole breaker. Two hot wires = two poles.
 
  #8  
Old 08-19-06, 09:06 AM
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Don't confuse a 240 volt double pole breaker with a twin breaker that only takes up one slot in the panel. A twin or mini breaker will have two connections, and two switches, however it can not be for your purpuse.
 
  #9  
Old 08-19-06, 12:45 PM
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**edit ** TO THE POINT post - sorry, point taken

What is the most wattage I can use on a 20 amp circuit?

Chawkey
 

Last edited by chawkey; 08-19-06 at 01:37 PM.
  #10  
Old 08-19-06, 02:31 PM
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Non-continuous load of 2400 watts on a 20 Ampere 120 volt circuit. Continuous load (defined as three hours or more continuous use) is 80% of the non-continuous load, or 1920 watts on a 20 Ampere 120 volt circuit.

Double those wattage figures if you are asking about a 240 volt circuit.


Note also that NEC requires fixed heating loads to have their branch circuits designed to 125% of the connected load.
 
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