New heater and thermostat

[dload001]

Hello All,

I need help :) i have a broken line thermostat and a broken 208v 2000 watts baseboard heater so i am planning to buy a replacement. The problem is on my circuit breaker the heater has 2 poles with a metal thing.. so i guess thats a double pole single throw.. not sure please correct me if i am wrong? when i took out the thermostat there were only 2 wires a black and red? and i was expecting 4? the voltage thats coming out is 215v so im guessing with the load and stuff it should be right for a 208v heater. I tried to buy replacements but could'nt find any? Can someone please recommend any store? All i find is dpst with 4 wires. :(

Thank you very much
Jay

[Wgoodrich]

Your wiring was a code violation from what I can understand. Power is coming from a 240 volt double pole breaker in the panel then ran to the heater. Then a switch leg is ran from the heater to the thermostat. The run to the thermostat should have taken both hots to that thermostat.

In your case you have an existing repair. Chances are your existing thermostat is probably fine.

I suspect your heater may have overheated burning out your high limit or your element has failed. Seldom have I found thermostats to fail.

What made you decide that both the heater and the thormostat went out at the same time.

Curious

Wg

[mdshunk]

First off, your breaker is likely two single pole breakers and the "metal thing" is a handle tie. Someone likely didn't have a double pole breaker when the installation was made originally, and used two single pole breakers with a handle tie. Same thing. Just not most people's first choice.

Secondly, your thermostat is only the single pole variety. It breaks only one of the hot wires. That's fine, although not my first choice for 240v heaters, but still perfectly functional. You really only need to break one of the hot wires to shut the heater off. You will likely find the other hot wire in the thermostat junction box wire nutted to the other wire to the heater. You should be able to get a single or a double pole thermostat anywhere electric baseboard heating equipment is sold. I'm sort of surprised you can't find a single pole one. You can use a double pole thermostat if that's all you can find. You can hook up both poles, or just use one of the two poles and put everything back as it was before. You'll just have an extra black and red wire on the thermostat that will be unused.

Jobs get done in sort of an oddball way like this when the installer is trying to use just what's on the truck without running to the supply house. There's nothing wrong with the way things are now.

[mdshunk]

Your wiring was a code violation from what I can understand. Power is coming from a 240 volt double pole breaker in the panel then ran to the heater. Then a switch leg is ran from the heater to the thermostat. The run to the thermostat should have taken both hots to that thermostat.

Wg


I'm interested to know what the violation would be by breaking only one wire of a 240v circuit? I know it's just not the way things are normally done, but I'm struggling to think of what the hazard is (other than to M, R, O personnell).

[dload001]

First off, your breaker is likely two single pole breakers and the "metal thing" is a handle tie. Someone likely didn't have a double pole breaker when the installation was made originally, and used two single pole breakers with a handle tie. Same thing. Just not most people's first choice.

Secondly, your thermostat is only the single pole variety. It breaks only one of the hot wires. That's fine, although not my first choice for 240v heaters, but still perfectly functional. You really only need to break one of the hot wires to shut the heater off. You will likely find the other hot wire in the thermostat junction box wire nutted to the other wire to the heater. You should be able to get a single or a double pole thermostat anywhere electric baseboard heating equipment is sold. I'm sort of surprised you can't find a single pole one. You can use a double pole thermostat if that's all you can find. You can hook up both poles, or just use one of the two poles and put everything back as it was before. You'll just have an extra black and red wire on the thermostat that will be unused.

Jobs get done in sort of an oddball way like this when the installer is trying to use just what's on the truck without running to the supply house. There's nothing wrong with the way things are now.



Wow you are so right!!!!!! thanks again to alll!!! The 2 wires were nutted. I will buy a dpst thermostat and a 240v heater. The old wiring was wrong i guess thats why thermostat was originally broken and the heater as well.

[mdshunk]

Not so fast... Mind what Wg has pointed out. How do you know you have a bad heater and a bad 'stat? I just took for granted you were sure they were both bad from other troubleshooting you may have done. Are they both visually broken (ie. - smashed)? I'd hate to see you spending money replacing something that's actually good. What I mean to say is your wiring (as it exists) should work. Do you know for sure that the heater is bad? Do you know for sure that the thermostat is bad? I can buy one or the other, but seldom (maybe never) both. People on this site can tell you how to test both.

[Wgoodrich]

424 controls fixed electric space heating such as baseboard heaters.

COPIED SECTION OF NEC 2002


424.20 Thermostatically Controlled Switching Devices.
(A) Serving as Both Controllers and Disconnecting Means. Thermostatically controlled switching devices and combination thermostats and manually controlled switches shall be permitted to serve as both controllers and disconnecting means, provided all of the following conditions are met:
(1) Provided with a marked “off” position
(2) Directly open all ungrounded conductors when manually placed in the “off” position
(3) Designed so that the circuit cannot be energized automatically after the device has been manually placed in the “off” position
(4) Located as specified in 424.19
(B) Thermostats That Do Not Directly Interrupt All Ungrounded Conductors. Thermostats that do not directly interrupt all ungrounded conductors and thermostats that operate remote-control circuits shall not be required to meet the requirements of 424.20(A). These devices shall not be permitted as the disconnecting means.

I mentioned that the original installation did not meet Code in my first reply. However I mentioned that this could be considered as existing. That actually would be ruled on by the AHJ of that jurisdiction though concerning existing because the original installation never met code minimums.

Hope this helps

Wg

[mdshunk]

Wg, I stilll don't see the violation by just breaking one leg. If the thermostat is also used as the disconnecting means, then of course, you have to break both legs per code. If the thermostat is just the controller, and the disconnect means is the breaker, as allowed in 424.21 (one section beyond what you typed), then the requirement to break both hot wires ceases to exist. You seem to be using a section that says the the thermostat MAY be used as controller and disconnect means (if it meets the list of criteria) and interpreting it as the thermostat MUST be used as controller and disconect means, and therefore must meet the list of criteria. Am I mixed up? Not arguing here, just trying to understand. Sometimes you need your lawyer to understand the code.

[Wgoodrich]

YOu are absolutely right that the breaker may be used as a form of disconnect for baseboard heaters as mentioned in 424.21. However that rule 424.21 does not tell you that you can use them only that when you can use them you they must be of the indicating type.

Refer to rule below; COPIED SECTION NEC 2002;

(1) Heater Containing No Motor Rated Over 1/8 Horsepower. The above disconnecting means or unit switches complying with 424.19(C) shall be permitted to serve as the required disconnecting means for both the motor controller(s) and heater under either item (1) or (2):

(1) The disconnecting means provided is also within sight from the motor controller(s) and the heater.

(2) The disconnecting means provided shall be capable of being locked in the open position.

Notice the rule above requires that breaker if used as the disconnecting form be either IN SIGHT OF HEATER or with a lock off device incorporated in the design of the breaker.

Notice that the unit switch [aka thermostat] if all hot conductors are broken by that unit switch may be used to fulfill the disconnect form and commonly is due to the fact that thermostat IS WITHIN SIGHT OF THE HEATER.

Insight or capable of being locked off in its design is required to serve as a form of disconnect. Thermostat meets the insight.

If only one hot conductor is disconnected leaving one hot conductor hot then that thermostat would not be allowed to be used as the disconnect form. If the panel is elsewhere in the dwelling not in sight of that heater then you would have a violation in design.

Also notice the thermostat may only be used as a form of disconnect if there is an OTHER FORM of disconnect. Then refer to rule C3 that allows IN A DWELLING that the breaker in the panel may be the OTHER formm of disconnect needed per NEC rules.

HOPE THIS HELPS

Wg

[mdshunk]

Okay... now I see it your way. I totally skipped the section you just referred to because I thought (skimming) that it applied only to heaters with motors. An electric baseboard heater has no motor over 1/8 hp. In fact, it has no motor at all. I was thinking "unit heaters" when I saw that section. The disconnect "within sight" makes all the difference. I'd never put a single pole thermostat on a 240V load anyhow. I'm not really sure why I was fussin' so much. I only carry double-poles on the truck and use them for single and double pole replacements.

[Wgoodrich]

Once you read the whole rule in detail about three times it finally sinks in. I know, I used single pole T stats for a decade until this crazy bull headed inspector stuck to his guns forcing me to prove he oops I mean I was wrong. Another one of those times when an electrician went to the Code to prove an inspector wrong and learned he was right and the electrician had to change what he had done for a decade not knowing he was wrong. I was that electrician. By the way I called that subborn old inspector and thanked him telling him that I proved him right !! Ha Ha.

We never stop learning in this electrical field until we stop looking and discussing, me included being that stubborn old goat inspector, now. Ha Ha Ya know you COULD argue with me on that last statement Ya know. Well it was a nice try on my defense, anyway.

Just having fun,

Wg