# Help understanding how single pole thermostat works?



## laclac01 (Oct 18, 2014)

I don't understand how my programable thermostat for my 220v electric baseboard heater works. Its a single pole thermostat, so only one hot in and one hot out. Its programable and uses no battery. How can just one hot power this programable thermostat. I could see if there was a ground attached to the thermostat it would use the ground as a return path. But there is no return path. 
Here is the manual of the thermostat i bought. 
http://www.homedepot.ca/wcsstore/Ho...alog/b7867367-6c05-4c82-a97c-648044b91564.pdf 


Same thing with a double pole, in that case its two hots and no return path.


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## V-Dough (Jul 22, 2014)

With the contacts in off position the device has 240V available. Maybe it has a battery that charges in off position so it can run when contacts close. Its just an educated guess, I hope someone can prove me right or wrong.


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## Black Dog (Oct 16, 2011)

laclac01 said:


> I don't understand how my programable thermostat for my 220v electric baseboard heater works. Its a single pole thermostat, so only one hot in and one hot out. Its programable and uses no battery. How can just one hot power this programable thermostat. I could see if there was a ground attached to the thermostat it would use the ground as a return path. But there is no return path.
> Here is the manual of the thermostat i bought.
> http://www.homedepot.ca/wcsstore/Ho...alog/b7867367-6c05-4c82-a97c-648044b91564.pdf
> 
> ...


What is the difference between the "Grounded Conductor" and the "Grounding Conductor"?

Welcome to the forum, if you are an electrician you can answer the above question.


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## 480sparky (Sep 20, 2007)

Same way an electronic dimmer works with only a hot and switch leg.


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## chicken steve (Mar 22, 2011)

all it needs is a capacitor...

~CS~


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## bkmichael65 (Mar 25, 2013)

Break out the old ammeter and I think you'll find a tiny current running through the baseboard at all times


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## laclac01 (Oct 18, 2014)

bkmichael65 said:


> Break out the old ammeter and I think you'll find a tiny current running through the baseboard at all times



You think or you know? Why is it such a secret? Could someone teach me the secret handshake? Maybe because no one knows and just goes be the instructions on how to wire and doesn't bother figuring out why. 

I guess i stumped the experts.


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## The_Modifier (Oct 24, 2009)

The first 2 diagrams have your answer ...... (hint something feeds through)

Just for curiosities sake, since you're south of the border, why are you using the Canadian **** depot link?

If you're an apprentice, please let the "experts" know, I will guarantee they will play a lot nicer.:thumbsup:



laclac01 said:


> You think or you know? Why is it such a secret? Could someone teach me the secret handshake? Maybe because no one knows and just goes be the instructions on how to wire and doesn't bother figuring out why.
> 
> I guess i stumped the experts.


Tip #2 if you reply like you did above with a snide remark, you won't really enjoy the comments.


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## laclac01 (Oct 18, 2014)

I'm sorry if I offend anyone. I am just looking for the answer. is there a way some expert could explain it vs not? i'd bow down to you.


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## The_Modifier (Oct 24, 2009)

laclac01 said:


> I'm sorry if I offend anyone. I am just looking for the answer. is there a way some expert could explain it vs not?


Ok, what part of the first to diagrams are you not understanding? Just to clarify a starting point.

Also, are you involved in the electrical trade? In Canada (keeping in mind, I have no idea what trade education is like in your country), this is something that is taught to a first term apprentice- I am in no way attempting to insult you.

If you could, please pick the diagram that you have installed the thermostat with, we can go from there.


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## laclac01 (Oct 18, 2014)

The_Modifier said:


> Ok, what part of the first to diagrams are you not understanding? Just to clarify a starting point.
> 
> Also, are you involved in the electrical trade? In Canada (keeping in mind, I have no idea what trade education is like in your country), this is something that is taught to a first term apprentice- I am in no way attempting to insult you.
> 
> If you could, please pick the diagram that you have installed the thermostat with, we can go from there.


I'm sorry i missed the post to the diagrams... I don't see it in the above. Maybe it was censored from my view. I understand how its supposed to be wired but I don't understand the concept.

I have 9 years of electrical engineering, but none of being an electrician, i'm trying to catch up.


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## The_Modifier (Oct 24, 2009)

The stat is a thermostatically controlled switch. Wether the feed through is the Neutral (120VAC) or another leg of power (240VAC)


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## The_Modifier (Oct 24, 2009)

laclac01 said:


> I have 9 years of electrical engineering, but none of being an electrician, i'm trying to catch up.


BTW Welcome, don't forget to post an introduction in *HERE* to let the rest of the community say hello as well. :thumbup:

And one last tip, add a little more information to your profile so others can connect with you if they have questions in your field as well.


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## The_Modifier (Oct 24, 2009)

laclac01 said:


> I'm sorry i missed the post to the diagrams...


My apologies, I was referring to the ones in the link that you posted in the first post. Sorry for the confusion my friend. I sometimes think faster than I can type.:laughing:


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## laclac01 (Oct 18, 2014)

The_Modifier said:


> The stat is a thermostatically controlled switch. Wether the feed through is the Neutral (120VAC) or another leg of power (240VAC)


thank you for your post. I understand how it works and how its wired. 
I'm just tried to understand how a circuit is created in the tstat enough to power the tstat when only a hot line is provided.

My understanding is that somehow the electrons have to make their way back from the tstat to the the panel. its hard for me to understand that when there is only a hot lead into the tstat. 

If the tstat was powered by a battery or mechanical way i would understand that is providing the power to open or close the switch. 

am i perceiving the answer incorrectly?


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## bkmichael65 (Mar 25, 2013)

laclac01 said:


> I'm sorry i missed the post to the diagrams... I don't see it in the above. Maybe it was censored from my view. I understand how its supposed to be wired but I don't understand the concept.
> 
> I have 9 years of electrical engineering, but none of being an electrician, i'm trying to catch up.


The feed parallels off inside the thermostat to power the controls and display. It has such a small current draw that it doesn't create any heat running through the baseboards. I wasn't trying to be cryptic with my earlier post, I just assumed that you would understand what I was saying. 
By the way, the secret handshake is only taught after you reach the 100 post mark


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## 480sparky (Sep 20, 2007)

laclac01 said:


> .......My understanding is that somehow the electrons have to make their way back from the tstat to the panel..........?



And they do. The load completes the circuit.


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## laclac01 (Oct 18, 2014)

"The feed parallels off inside the thermostat" is what i don't understand. how does that actually work? how do they electrons actually get back to the panel with that?


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## bkmichael65 (Mar 25, 2013)

laclac01 said:


> "The feed parallels off inside the thermostat" is what i don't understand. how does that actually work? how do they electrons actually get back to the panel with that?


Just like your television. One cord and plug containing two wires. The power splits from one wire to power monitor, speakers, etc and then then returns on the other wire


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## 480sparky (Sep 20, 2007)

laclac01 said:


> "The feed parallels off inside the thermostat" is what i don't understand. how does that actually work? how do they electrons actually get back to the panel with that?



The 'stat turns a switch/relay on and off to control the heater. That's one of the parallels in the 'stat. The other takes power from the hot, runs it through the electronics, then out to and through the heater and back to the panel. THAT is how the electrons get back to the panel...._ through the load that completes the circuit_.


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## laclac01 (Oct 18, 2014)

but in this situation there is one wire. Not two.

In television it involves many frequencies and waves on one wire. its not the same.


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## laclac01 (Oct 18, 2014)

but in this situation there is one wire. Not two.

In television it involves many frequencies and waves on one wire sending data analog or digital. its not the same.


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## 480sparky (Sep 20, 2007)

laclac01 said:


> but in this situation there is one wire. Not two.
> 
> In television it involves many frequencies and waves on one wire sending data analog or digital. its not the same.



We're not talking about the RF signal here. :no:


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## RIVETER (Sep 26, 2009)

laclac01 said:


> I don't understand how my programable thermostat for my 220v electric baseboard heater works. Its a single pole thermostat, so only one hot in and one hot out. Its programable and uses no battery. How can just one hot power this programable thermostat. I could see if there was a ground attached to the thermostat it would use the ground as a return path. But there is no return path.
> Here is the manual of the thermostat i bought.
> http://www.homedepot.ca/wcsstore/Ho...alog/b7867367-6c05-4c82-a97c-648044b91564.pdf
> 
> ...


I did not go to the link but will say that all electrical devices work because of a difference of potential. From phase to phase there IS a difference of potential. Switching one leg (phase) is how it's done.


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## bkmichael65 (Mar 25, 2013)

laclac01 said:


> but in this situation there is one wire. Not two.
> 
> In television it involves many frequencies and waves on one wire sending data analog or digital. its not the same.


No, there are two conductors attached to your thermostat. All The current going out on one conductor will return on the other. Even if your thermostat is not calling for heat, there will still be a minute amount of current still running through that baseboard heater returning to panel to power the thermostat.


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## 480sparky (Sep 20, 2007)

Here's a diagram of a thermostat that has turned off the heater.

Do you see the completed circuit now?


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## laclac01 (Oct 18, 2014)

yeah i know. A regular coax cable for TV does waves, many different frequencies down one wire in different modulation schemes. Thats how it transmits data. BPSK, QPSK ect. 

I am saying its not like a TV wire as you suggested. I am just asking about how the electrons actually get back to the panel or a ground when its just a line in and a load out and nothing else.


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## laclac01 (Oct 18, 2014)

480sparky said:


> Here's a diagram of a thermostat that has turned off the heater.
> 
> Do you see the completed circuit now?


both the power the leads from the power are hot. Each leg is 110V. only the heater is grounded. That picture doesn't show the return path.

Im sorry if i am being difficult. Maybe i am just looking at the science behind it.


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## CADPoint (Jul 5, 2007)

The secret hand shake is that if your break the circuit, you've broken the circuit! IE it's not a complete circuit and the Amps don't flow.

While the internal wiring of the thermostat(based on OP) is not shown in the technical
illustration you can almost count on the fact that there is something isolating the hot wire of one circuit, thus it doesn't "complete the circuit" as needed!

Ask Google, use Images; Define 240V thermostat... :thumbsup:


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## bkmichael65 (Mar 25, 2013)

laclac01 said:


> yeah i know. A regular coax cable for TV does waves, many different frequencies down one wire in different modulation schemes. Thats how it transmits data. BPSK, QPSK ect.
> 
> I am saying its not like a TV wire as you suggested. I am just asking about how the electrons actually get back to the panel or a ground when its just a line in and a load out and nothing else.


I was talking about the power to the tv, as an example. I'm obviously not too good at explaining this concept. Now that 480 has drawn a picture for you, is it clear?


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## 480sparky (Sep 20, 2007)

laclac01 said:


> ..That picture doesn't show the return path..........



You're not looking hard enough.

There is a completed circuit shown.

Start at the top left, and follow the black line to the right. It goes to the electronics in the stat (shown by the gray line), then *the circuit is completed by the load*.


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## RIVETER (Sep 26, 2009)

480sparky said:


> You're not looking hard enough.
> 
> There is a completed circuit shown.
> 
> Start at the top left, and follow the black line to the right. It goes to the electronics in the stat (shown by the gray line), then *the circuit is completed by the load*.


Truely...a teaching moment.:thumbsup:


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## laclac01 (Oct 18, 2014)

CADPoint said:


> count on the fact that there is something isolating the hot wire of one circuit


But there is only one hot going in to the Tstat so I guess i don't understand why you would suggest there are more than one circuit.

If that one hot wire powers up the PROGRAMABLE tstat, where is its return path for that hot wire.


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## RIVETER (Sep 26, 2009)

laclac01 said:


> But there is only one hot going in to the Tstat so I guess i don't understand why you would suggest there are more than one circuit.
> 
> If that one hot wire powers up the PROGRAMABLE tstat, where is its return path for that hot wire.


As the current...however slight, travels through the "stat", a difference of potential is created within the "stat". The rest is a mystery.


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## laclac01 (Oct 18, 2014)

480sparky said:


> There is a completed circuit shown.
> 
> [/B].


Both are 110 legs for 220V. You are suggesting that two 110 hots make a completed circuit.


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## 480sparky (Sep 20, 2007)

laclac01 said:


> But there is only one hot going in to the Tstat so I guess i don't understand why you would suggest there are more than one circuit.
> 
> If that one hot wire powers up the PROGRAMABLE tstat, where is its return path for that hot wire.


Once again: *THE LOAD COMPLETES THE CIRCUIT*.





There are two circuits created inside the 'start. One is simply an on/off switch controlled by the electronics. The other is the electronics in the 'stat. When the heater is turned off, only one of the circuits (the electronics) carries current. When the stat calls for heat, the second (parallel) circuit is closed, and current flows through both.


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## 480sparky (Sep 20, 2007)

laclac01 said:


> Both are 110 legs for 220V. You are suggesting that two 110 hots make a completed circuit.



Do you not see the completed circuit that allows current to flow, even when the heater is turned off by the stat, as shown in the diagram?


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## CADPoint (Jul 5, 2007)

laclac01 said:


> But there is only one hot going in to the Tstat so I guess i don't understand why you would suggest there are more than one circuit.
> 
> If that one hot wire powers up the PROGRAMABLE tstat, where is its return path for that hot wire.



No it's 240V and both are hot they broke one so the resistor designed to handle
240V volts and X number of amps doesn't work because there is no complete path for the electrons to go back and forth...OH snap - two points


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## RIVETER (Sep 26, 2009)

laclac01 said:


> Both are 110 legs for 220V. You are suggesting that two 110 hots make a completed circuit.


Okay...you are young. YES, two hots, AKA ,phases, if they are different phases will pass current between them because of the difference of potential between them.


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## 480sparky (Sep 20, 2007)

The applied voltage is not relevant to the circuit being completed. It still works whether it's 120, 208, 240......


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## CADPoint (Jul 5, 2007)

Ok, Let's really shake him up and state that it's One Phase - 180 degrees
apart. Do I get extra points for weekend posting - snap two points
( robbed of thousands )


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## laclac01 (Oct 18, 2014)

RIVETER said:


> Okay...you are young. YES, two hots, AKA ,phases, if they are different phases will pass current between them because of the difference of potential between them.


But when you break the hot like in the off position (or not calling for heat), that means there is no connection whatsoever with the other phase or even connection with the load. But the Tstat is still powered up and its back lights are on.


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## Mich drew (Mar 3, 2013)

As 480 showed you in the diagram, even when the stats contacts are open, current can still flow through the electronics in the stat, through the load, and back to the panel. Have you ever seen a glowing light switch? Same concept.


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## CADPoint (Jul 5, 2007)

Mich drew said:


> As 480 showed you in the diagram, even when the stats contacts are open, current can still flow through the electronics in the stat, through the load, and back to the panel. Have you ever seen a glowing light switch? Same concept.


Look at your original technical illustration both circuits go to the T-Stat...

IE thus a complete circuit of 120 or in this case a 240.


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## RIVETER (Sep 26, 2009)

laclac01 said:


> But when you break the hot like in the off position (or not calling for heat), that means there is no connection whatsoever with the other phase or even connection with the load. But the Tstat is still powered up and its back lights are on.


I have got to hand it to you. You are trying to drill down to the CORRECT...RIGHT answer. That has been my worst enemy...not pursuing. Keep it up and I am sincere in saying this.:thumbsup:


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## laclac01 (Oct 18, 2014)

I thank you all for your time. I think i found what I am looking for, i must not have made myself clear. There is actually a mathematical formula that calculates this and it based on the number of hertz.


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## Shock-Therapy (Oct 4, 2013)

laclac01 said:


> I have 9 years of electrical trolling, but none of being an electrician, i'm trying to catch up. Sincerely yours, Cletis!



FIFY :thumbsup:


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## RIVETER (Sep 26, 2009)

laclac01 said:


> I thank you all for your time. I think i found what I am looking for, i must not have made myself clear. There is actually a mathematical formula that calculates this and it based on the number of hertz.


Wow!!!!! After all we have done to try to help you, you didn't need us in the first place. Man, that HERTZ...I mean HURTS.


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## laclac01 (Oct 18, 2014)

Shock-Therapy said:


> FIFY :thumbsup:


9 years of college then 12 years of experience...


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## 480sparky (Sep 20, 2007)

laclac01 said:


> I thank you all for your time. I think i found what I am looking for, i must not have made myself clear. There is actually a mathematical formula that calculates this and it based on the number of hertz.



What does the frequency of the AC voltage have to do with it? :001_huh:


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## RIVETER (Sep 26, 2009)

laclac01 said:


> 9 years of college then 12 years of experience...


Counting my military training I have had 23 years of classroom training and I am still not as smart as I think I am.


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## RIVETER (Sep 26, 2009)

CADPoint said:


> Ok, Let's really shake him up and state that it's One Phase - 180 degrees
> apart. Do I get extra points for weekend posting - snap two points
> ( robbed of thousands )


Subtract 60 degrees.


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## CADPoint (Jul 5, 2007)

RIVETER said:


> Subtract 60 degrees.


3 phase has not been in the discussion! 2 more yahoo's


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## RIVETER (Sep 26, 2009)

CADPoint said:


> 3 phase has not been in the discussion! 2 more yahoo's


Pardon me. I guess the 180 threw me.


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