# Can telephone wire be used for theromostat wire?



## Joey Jones (Sep 27, 2008)

Seems to be about the same gauge as thermostat wire. I just happen to have very many feet of telephone 4 strand cable hanging around and a need for new thermostat wire
Thanks Joey C


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## CowboyAndy (Sep 27, 2008)

No, most telephone wire is 22 or 24 gauge. Tstat wire needs to be 18.


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## Joey Jones (Sep 27, 2008)

Thanks Cowboy...Much appreciate it
Joey Chang


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## cncpro (Sep 30, 2008)

Sorry for the personal attack here....

But I can't resist...

Sawdustburners, after reading some of your recent posts I just have to ask...

Do you go through a lot of duct tape while maintaining the homestead ?


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## EddyKilowatt (Sep 30, 2008)

Cncpro, I don't know if your folks passed this saying forward to you from the hard times they lived through, but you might try it on for size, since you (and all of us) may have use for it in the near future: 

"Use it up.  Wear it out.  Make it do."  

I won't speak to either the Code aspects of what JoeyJ is asking, nor the technical aspects of what gauge of wire might be needed for a t'stat... but I will say that what Sawdust is suggesting is an entirely reasonable and sensible solution, if all that is needed is a few less ohms in the loop.  It'll save a few bucks (that would otherwise go to Chine) that can probably be put to better use somewhere else.

Eddy


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## Joey Jones (Sep 30, 2008)

Yeah, it seems to make sense to me ...it is only braided wire and braided wire is used for lots of things, like  $2500 SPEAKERS, ETC


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## Joey Jones (Sep 30, 2008)

sawdustburners said:
			
		

> cncpro said:
> 
> 
> 
> ...



Yes I do always keep at least a case of duct tape on hand...as Red Green says..."If the women don't find you handsome thay should at least find you handy....


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## webbie (Sep 30, 2008)

Don't underestimate tape - here is our local Nuclear Plant using it - no kidding, Yankee Nuclear in VT.

Phone wire would probably work fine in most millivolt situations, but some thermostat wire has decent current going through it (like 24V control loops), so - as always - why not use the right stuff. 

It might leak more current and not complete the circuit in long runs....the lighter wire, that is. I'm sure our EE members will clarify.


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## GVA (Sep 30, 2008)

tried it once but the phone rang everytime the furnace was CALLING for heat..... :cheese:


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## Hogwildz (Sep 30, 2008)

Most T stat wiring I ever seen was solid wire, not stranded.


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## woodsman23 (Sep 30, 2008)

The wire will work just fine try it then you will know.


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## pastera (Oct 1, 2008)

Taco heat motor zone valves take 0.9 amps at 24Vac (~27 ohms)

Standard telephone wire is 24 AWG - resistance 27.3 ohms per 1000'

18 AWG wire is 6.6 ohms per 1000'


The acceptable length for 24 AWG would be 1/4 of that for 18AWG (6.6/27.3)

Aaron


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## Brian VT (Nov 14, 2008)

Aaron Pasteris said:
			
		

> Taco heat motor zone valves take 0.9 amps at 24Vac (~27 ohms)
> 
> Standard telephone wire is 24 AWG - resistance 27.3 ohms per 1000'
> 
> ...




So....telephone wire would be okay out to 250' ?


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## Gooserider (Nov 17, 2008)

Haven't tried it, but I would expect that it would depend on the application.  There is considerable difference between the wire needed for a thermostat circuit where you are just using tiny amounts of current to trip a control relay, and a circuit that would be driving a zone valve or other motorized / heavy draw component...

I also don't know what the rules are code wise, but I would expect that using something like Cat5e ethernet cable (nowadays used much more than phone cable) would be possible if you used several conductors on each leg of the circuit - I know I've heard of that being done on applications like TV antenna rotator control circuits.

(note - to reduce magnetic fields, use one wire from each pair on one side, and the matching wires on the other side - i.e. + side use the solid wires, - side use the striped ones.  Don't use both wires from one pair on the same side)

Gooserider


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## TheIglu (Nov 17, 2008)

I just used Cat5E, worked fine for the digital thermostat. Barely any current going through there.


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## EatenByLimestone (Nov 18, 2008)

When I swapped my thermostat the wire was smaller than phone line.  Then again, it probably is only 10-15 feet long depending on the route they took when they put it in.  My thermostat practically above my furnace.

Matt


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