Help to trouble shoot wall heater ckt

[baronson]

original electrician wired for a dedicated 20 amp / 2pole ckt for future cadet wall heater. he ran from the subpanel to a blanked off box. from this point i put a thermostat in the blanked off box, fished a wire from there and cut in a wall heater. so I flipped the breaker and even though the thermostat was on the lowest setting it started right up and never stopped. i cranked the thermostat to 70 and the whole circuit as well as the subpanel main tripped. okay so i thought something wrong with thermostat as i pulled the heater from the wall and with the therm. at the lowest setting, i had 240v. i would think since the therm is basically a rheostat, the 40 degree (or the lowest setting) should measure out at 120v or something. anywho i changed out he therm. and same thing happened. the heater and fan will not turn off and when i turn the therm. to 70 ish degrees. the whole thing trips. ?? help

 

[Local Electrician]

original electrician wired for a dedicated 20 amp / 2pole ckt for future cadet wall heater. he ran from the subpanel to a blanked off box. from this point i put a thermostat in the blanked off box, fished a wire from there and cut in a wall heater. so I flipped the breaker and even though the thermostat was on the lowest setting it started right up and never stopped. i cranked the thermostat to 70 and the whole circuit as well as the subpanel main tripped. okay so i thought something wrong with thermostat as i pulled the heater from the wall and with the therm. at the lowest setting, i had 240v. i would think since the therm is basically a rheostat, the 40 degree (or the lowest setting) should measure out at 120v or something. anywho i changed out he therm. and same thing happened. the heater and fan will not turn off and when i turn the therm. to 70 ish degrees. the whole thing trips. ?? help

Are you sure you got a 120 or 240 heater.
I set the thermostat to off when ever I turn it on. And make sure it does not come on with the thermostat off.
It sounds like you may have some wires crossed.

 

[480sparky]

I'd check the heater and make sure it's a 240 volt unit.

 

[Rewire]

The T state is a switch and just turns the heater on and off at preset points so nomatter were the state is when it calls for heat you get 240V the first thing I would check is that you have a 240V heater. next check that you have a line voltage thermostate and that you have it correctly wired in and out.I had an apprentice wire a T state once by twisting the hot legs together a to a and b to b and then putting the T stat across a and b when he powered up the heater came on and when he turned up the stat to call for heat it closed and shorted the breaker. I would check and make sure the line attaches to one side of th TY state and the load attaches to the other side of the T stat

 

[charlietuna]

Check the voltage at the junction box with nothing connected--then check the nameplate "ON' the heater--not the box it came in, for the voltage.

 

[LarryFine]

Baron, I have the feeling you wired the T-stat incorrectly. If there are two red wires and two black wires, you should connect the incoming power to the two blacks and the heater wires to the two reds.

 

[cadpoint]

Off is a good start, a no load test is just to turn the dial and see if you hear the click of the thermostat. I beleive it still comes down to a 2 layer metal (can't think of the word) component.

I just wired up a 5000W portable heater for temp service, 208/240 and a fused disconnect. There were only a Black and a White and a ground and cut the big plug loose...:-?.

This model had a dial and a switch IE an off or auto setting switch and a seperate rotatory dial of about 270?'s...
I left it on auto, and dialed it down... and the LED was burning...

 

[kbsparky]

Sounds like that thermostat is wired in parallel with the heater. It should be wired in series, so opening the stat disconnects power to the unit.:-?

You have a dead short when you turn up the thermostat.

 

[ActionDave]

i would think since the therm is basically a rheostat,

The Tstat (therm) is basically a switch. Do what Rewire said the way Larry said for the reason kbsparky said and when all is said and done the heat should radiate from said heating unit.

 

[e57]

i cranked the thermostat to 70 and the whole circuit as well as the subpanel main tripped.

Hmmmm....

okay so i thought something wrong with thermostat as i pulled the heater from the wall and with the therm. at the lowest setting, i had 240v.

As one would expect....

i would think since the therm is basically a rheostat, the 40 degree (or the lowest setting) should measure out at 120v or something.

Here you are dead wrong! You should get 240v in - 240 out. This is a by metal switch - depending on if you are using a 2P vs a 1P, (the later requiring a diconnecting means, and both would if there is no "OFF" position on said thermostat) a 1P would need to send one leg straigh through - the other switched by the thermostat...

anywho i changed out he therm. and same thing happened. the heater and fan will not turn off and when i turn the therm. to 70 ish degrees. the whole thing trips. ?? help

Hows the temp in the room - it will switch off around that temp - anything lower it will stay on.... As it is supposed to.

Now - I say you have a look see at the thermostat - if a cadet model - it may have two red wires, and two black wires. Contrary to popular notions of color coding they're often line (red) and load (black) respectively. (Look very carefully for the markings...) What you may have done is assumed that the black be pole #1 in + out, and red be pole #2 in + out. When you crank the knob and the bi-metal switch on one pole of the thermostat trips at 70, the switching goes phase to phase. (tripping the main etc.) When not at that point the other pole is switched once you click past the "OFF posistion. Not sure why it would operate at that point - unless there is also a short to ground.... :-?:-?

http://www.cadetco.com/support/ownersguides/1017.pdf

Don't want to sound insulting - but that thing does say to call a qualified electrician....

That said - i recently had one of these that an apprenti was left to install at a 'Pull out and paint job' while I was busy on other tasks - just like the other two I watched him put in - something simular happened, and it turned out the factory put different colored wires on different terminals than the others in the bunch....

Either way - electric heat is a waste of money, energy (not that I care) and all a round just a poor way to heat a room.... (Also illegal in California)

 

[lbwireman]

Either way - electric heat is a waste of money, energy (not that I care) and all a round just a poor way to heat a room.... (Also illegal in California)

Details please. Is this CEC Title 24? Other CEC issue? Or? Not disputing your statement, just hoping for substantiation/citation. We have several customers who are MFDs and use in-the-wall or the old Gold Medallion resistant wire in the ceiling heating. Since we deal with these as service calls (when they quit working), upgrades (customer understands inefficiency and the concept that "heat rises"), customer wants retrofitted recessed can lighting), it would be useful to be able to cite why we can't legally accommodate their desires.

 

[76nemo]

If you look at the t-stat, or manual, you will notice that there is line and load sides to it. You most likely have it wired in reverse.

 

[Rewire]

I wish the OP would come back and tell us what the problem was

 

[baronson]

the heater itself..nameplate 240 /208, the tstat is a line volt single pole for 240/ 208 / 120. there are only two leads then ...thinking maybe i'm just crazy i switched the leads..to no avail or should i say difference. the heater turns on automatic (the temp of room is over 50 degrees so i can't see the tstat just trying to get up to temperature.) and again doesn't turn off...at all. when i turn the tstat to around 70 degrees..pop goes the breaker and the main to subpanel. as this was a favor to a nice lady neighbor, instead of trying to figure out what the first electrician did (?) or had in mind ..sorry to say my advise is to call the guy back and have him finish the job. thanks for the advise, as a QUALIFIED electrician with a minimum experience with tstats and heaters let alone troubleshooting , im thankful there is a forum to put out my questions

 

[charlie]

. . . it still comes down to a 2 layer metal (can't think of the word) component. . .

Bimetallic strip where the coefficient of expansion is different for each. Therefore, it bends as it is heated or cooled. :smile:

 

[LarryFine]

the heater turns on automatic ... and again doesn't turn off...at all. when i turn the tstat to around 70 degrees..pop goes the breaker and the main to subpanel.

It sounds like the heater and thermostat are wired in parallel.

 

[Cow]

This is basic troubleshooting, I'm really having a hard time understanding what the difficulty is.:-?

Here is a very simple test. Have you tried bypassing the t-stat and direct wiring the heater to the breaker?

It works=t-stat problem
It doesn't work=heater problem

 

[LarryFine]

I have another suggestion: Start by disconnecting all four wires at the T-stat location (there are four wires, right?) and test for proper power (120 and 240v) on two wires.

Also, make sure the heater is not heating now. Then, try connecting those two directly to the other two (as Cow suggests), and seeing if the heater heats with no problem.

The T-stat should have four wires on it. Usually, each section has one red and one black wire. The supply should connect to the two blacks, and the heater to the two reds.

 

[LarryFine]

Okay, just noticed you have a single-pole T-stat, so there should only be two wires. That means you'd wire it like a switch, to the blacks, with the whites connected together.

It sounds like the whites are together, the blacks are together, and the T-stat is wired between the two joints. I'd try what I suggested in the first two paragraphs above if this doesn't work.

 

[iaov]

I don't think it being a 120 or 240 is what the problem is although like others have said you need to confirm this. You also need to see just what you have for voltage coming into your jb is. The fact that you are clearing the main in the sub tells me you are directly shorting either a phase to neutral or phase to phase when the thermostat closes.