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-   -   erratic thermostat being warmed behind from wires? (http://www.diychatroom.com/f18/erratic-thermostat-being-warmed-behind-wires-160706/)

hbirch 10-21-2012 11:31 AM

erratic thermostat being warmed behind from wires?
 
Hi there,

I am in a funky (owner-built in the 50s, 'summer home') rental house with electric baseboard heat. One of the thermostats (double pole) was an old piece of junk and impossible to control and very inaccurate. I replaced it with a newer honeywell double pole thermostat and am experiencing the same problems. It kicks off too early and then even if you turn it up to 85 and it's 65 in the room it wont kick back on for a while (no click either). I had a theory that it was actually getting too warm from the wires because they've got two six foot and one four footer running off of this and I believe they are running at 120V (220 would have more than 1 white and 1 black wire, right? -- in the junction box that's all there is on the load side/line side respectively). There's no labeling inside these baseboard heaters but online research has told me to estimate the total wattage as 4000 watts.

I felt the thermostat and it was warm to the touch when the house was 65 and it refused to kick on even when turned all the way up (but 30 minutes later, once the wires cooled my bet, it would kick on just fine). So I'm pretty sure this is indeed what is happening (wires too warm).

So, questions:

1.) Is this normal behavior or does it indicate that something is overloaded/wrong with the wiring?
2.) Is reducing the load by disconnecting the 4 foot unit from the sequence likely to make a difference (theoretically bringing it down to 3000 watts -- which also allows me to use nicer, cheaper, digital programmable thermostats)?

AllanJ 10-21-2012 01:19 PM

A 220 (240) volt only appliance can be run off of just black and white wires connected up to a double breaker installed in the panel so as to have 240 volts between the two breaker terminals. (You may find two single breakers in older installations.)

If the wires are too thin, then they will heat up excessively. A 12 gauge wire can handle 16 amps at either 120 or 240 volts continuously. A 14 gauge wire can handle 12-1/2 amps continuously.

If the thermostat or switch assembly is noticeably warm you should also check for and tighten up any loose connections.


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