Thermostat Wiring Electrical Code

Is there an electrical code for thermostat wiring? I know that there's typically 24 VAC across the wires at probably a very small current level, perhaps much less than half an amp.
I'm considering moving a thermostat and was considering using either solid or stranded 18 gauge wire. Its for a simple hot water baseboard radiator system, no HVAC.
Handi
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Go to Home Depot or equivalent and buy some "thermostat" cable. Choose between two, three or five wires based on what you now have or your thermostat needs. If you have to join cables you can wirenut the wires together (add some tape to prevent any accidental contact loosening the wirenuts). They don't need to be in a box.

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For hot water heat only, the fellow is likely going to use 18-2, which is red and white.
I also use wirenuts and then tape when something might come loose. And when I'm doing heating, I often wear belt and suspenders.
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Christopher A. Young
Jesus: The Reason for the Season
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I agree, if your going to bury the splices I would use crimps on the wires instead of wire nuts. Test everything before you move on.
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The NEC doesn't regulate low voltage wiring.

Either will work, like the other poster said, go and get some thermostat wire that matches the number of wires, so the colors are the same for simplicity sakes, and extend as needed.
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wrote:

The NEC most certainly does regulate low voltage wiring. Thermostat, telephone, TV, cable TV, Cat 5 (etc.), sound circuits, door bell, intercom, low voltage lighting controls, and more, even landscape wiring is covered by the NEC. Thermostat wiring is usually Class 2, which is addressed by NEC Article 725. Probably the biggest concern is that the low voltage cables be installed and terminations made such that they will not be (accidentally) energized by higher voltage circuits.
They should also be protected from nail and screw penetration.

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On 24 Jan 2004, volts500 wrote:

Duh. Imagine that.

Wow. Common sense. No shit, Sherlock.
Crawl back into your hole, anal-retentive codebot.
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The NEC does address low voltage wiring but no area I'm aware of inspects so it is of no effect. Remember that electricians are a guild and would like to prevent anyone not a member to be prohibited from competing.
I'm ducking now, having made a poignant observation.
RB
John Hines wrote:

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Locally, it is inspected and required to be permitted. Most of the code is related to not connecting low voltage to any standard wiring, and that's what the inspector's are looking at for the most part. Commercially, they get very concerned about fire wall penetration, as they do in multi-family residential. The other thing they are looking at locally now is grounding, especially concerning low voltage lighting and voice/data/entertainment with external connections.
But that's local issues. We have a very high percentage of new and remodel construction that involves extensive low voltage for entertainment, alarms, lighting, data/voice and so on, so that's one reason it shows up on the inspector's radar here.
Jeff

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I suspect the real reason it shoes up on the inspector's radar is that they are worried about the "brotherhood" loosing out if too much moves to low voltage control. They will next want to inspect optical signal distribution.
May the Guilds be perpetuated.
Thankfully, I'm in an unincorporated area that doesn't inspect anything. It's great.
RB
Jeff Cochran wrote:

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Any low voltage that *controls* high or line voltage apparatus is within the jurisdiction, and the legitimate concern of the NEC or your local AHJ.

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I'll also point out that the NEC rules are not only safety related, but _also_ help improve the resulting system for the homeowner's benefit.
NEC/CEC rules talk about keeping separation (between power and LV) more than 1' and crossing at right angles "as much as possible".
Why? Well, of course, there's a paranoid safety element in there. But following those rules also helps reduce hum and crosstalk in cable TV, antennas, telephones, hi fi systems etc.
So, whether you care about the safety-nazi bit or the union bit or not, following those rules as much as you can _is_ to your benefit in a better quality installation and less electrical noise.
--
Chris Lewis, Una confibula non set est
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