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We have a propane fireplace insert that can be wired up for a switch.

Right now, there are two 6" 18g single-strand leads that when nutted together complete the circuit allowing the fireplace to turn on when the main dial is st to 'on'. If you disconnect them, it goes back to pilot.

You can leave these connected and then turn the fireplace on by removing the front plate, but I wanted to hook up a remote switch to make it less of a chore. I went and got a low-voltage switch and ran 6' of 14g stranded wire to the switch to the two leads on the fireplace.

Alas, this doesn't work.

I'm guessing it's too much resistance to complete the circuit...either by length or gauge. Is there a rule of thumb here? If I go get single strand 18g would that work? Is there a way to calculate this short of trial-and-error?

UPDATE:

Well, I found an answer for my particular needs via trial an error. I'm not answer the question as there's probably a legitimate electrical formula for calculating this.

I took out the #14 stranded and replaced it with #18 stranded. Same length. But this works.

  • The easy workaround would be to replace the switch with a relay, and extend the relay's control loop rather than the fireplace's own circuit. Then you'd know the exact specs for the relay and be able to make the appropriate calculations. Of course the manufacturer may also offer a remote control accessory, which would have the advantage of not voiding the warranty. – keshlam Jun 29 '14 at 4:19
  • Interesting idea...but wouldn't a relay have to be powered? – DA01 Jun 29 '14 at 5:15
  • Sure, but a cheap plug-in transformer can handle that -- including a leftover wall-wart from any random bit of electronics -- if you pick an appropriate relay. Nice thing about relays is that they let low-voltage circuits control higher voltage, while maintaining isolation between the two. – keshlam Jun 29 '14 at 13:00
  • Chapter 9 table 8 of the NEC, says that #14 stranded copper has a resistance of 3.14 ohms/kFT (10.3 ohms/km). #18 solid is 7.77 ohms/kFT (25.5 ohms/km). this answer, explains how to calculate the maximum length of a conductor. – Tester101 Jun 29 '14 at 13:27
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    Maybe the switch is the problem? Have you tried just connecting the wires together to complete the circuit - does the fireplace turn on? – Steven Jun 29 '14 at 14:59

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