Electric baseboard thermostat problem

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  #1  
Old 11-01-14, 11:27 AM
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Electric baseboard thermostat problem

trying to replace faulty thermostat on existing circuit. circuit has been in place for years,working fine. recently heat would not stay on, so replacing thermo. it is 5 four foot baseboards, (slantfin) ratings: 120 v.a.c 1500 watts each. 30 amp dual pole breaker. power goes to wall thermostat and then feeds baseboards in a line. Thermostat bought to replace doesnt keep heat on. im told by electrician that they do not make thermostat to handle this load but it has always worked in past. looking for ideas. thanks
 
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Old 11-01-14, 12:20 PM
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120 v.a.c 1500 watts each. 30 amp dual pole breaker
A bit confusing. A dual pole breaker is 240 volts not 120 volts. How are there wired?
 
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Old 11-01-14, 12:58 PM
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in a string..power to the first..wire connects to second etc.
 
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Old 11-01-14, 01:19 PM
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If you are saying series connected that would be only 48 volts per heater. It would have to be a series/parallel but that would require an even number of heaters and you wrote five heater. Are you sure it isn't a tandem breaker not a dual pole breaker.
wire connects to second
Do you mean cable? Is it 2-conductor (black and white) or 3-conductor (white, black, red) or is it conduit.
 
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Old 11-01-14, 01:46 PM
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it is 5 four foot baseboards, (slantfin) ratings: 120 v.a.c 1500 watts each.
Are you sure? Please double check. Most high watt density baseboard heaters run about 250 watts per foot; a 4 footer would be 1,000 watts. It would be unusual to find this many 120 volt heaters, but at 120 volts, the 5 heaters @1500 watts each would draw 62.5 amps. There would be no way to power those heaters with even two 30 amp circuits.
 
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Old 11-01-14, 03:24 PM
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sorry There are 5 baseboards that are 5 feet long with the below tag

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Last edited by PJmax; 11-01-14 at 03:33 PM. Reason: reoriented picture
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Old 11-01-14, 03:36 PM
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That's 12.5A per heater at 120v. That would be 62.5A of current draw.

I'm very confused as to how these 120vac heaters are wired to a 240vac circuit.
I can't figure how a 2P30A breaker can handle the load.
You have 37.5A on one breaker and 25A on the other breaker.

Also... one thermostat IS too small for a load this heavy.

If the circuit you have described is in place then #10 wiring would have needed to have been used. It sounds like a multiwire branch circuit is in place and you are using one thermostat to switch both 120v legs.
 
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Old 11-01-14, 04:12 PM
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Thanks, like i said just trying to replace whats there. consider myself advanced DIY'er but not electrician. is it possible there is a relay or something in the wall i cant see that went bad? is it possible to run three of these baseboards off one thermostat? i can take the last few out of the string.
 
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Old 11-01-14, 04:18 PM
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Can you remove the breaker panel cover and give us a shot of the breaker the heaters are on and include a couple of breakers on either side so we can clearly see how the circuit is connected at the breaker box.
is it possible there is a relay or something in the wall i cant see that went bad?
That wouldn't explain a 30 amp 240 vol supply.
 
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Old 11-01-14, 04:49 PM
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sure its the one pictured with the zip tie Name:  image.jpg
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  #11  
Old 11-01-14, 05:51 PM
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That is two single pole 120 breakers. I can't understand how that wiring could be correct. Did you add the zip tie or is that original? You have a non code compliant 240v only feed to 120 volt appliances. Unless they used the ground as neutral it can't be a multiwire circuit. What is the wiring at each heaters junction box?
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  #12  
Old 11-01-14, 07:19 PM
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Wow.... I certainly didn't expect to see white and black on those breakers.

The highest rated thermostat I know of is 22amp.

I have to tell you... I am very concerned with that heater setup.... almost to the point where I would highly recommend bringing in an electrician. I know it has been working but that doesn't mean that it is safe. You have a severe overload on that circuit and it needs to be addressed.
 
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Old 11-01-14, 07:27 PM
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thanks guys. yeah i think im at the point to bring in a pro. it had been working in the past but im nervous with your comments. turned off the breaker and will make some calls. thanks for the insight. will post how it turns out.
 
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Old 11-01-14, 07:31 PM
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I don't mean to scare you but something is not quite right there. Better to be safe than sorry.
Please keep us posted on the outcome.
 
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