I'm finishing my basement and have many existing splices of 18 gauge (2 wire) for thermostats and the alarm system and central vac. I'll run new wire where I can but it's not an option for many unfortunately. I'm trying to avoid my ceilings and walls being splattered with white plate covers all over. I know that Tyco had special connectors for splices of 12/2 romex cable which could be concealed behind drywall (meeting NEC 334.40(B)), but I'm having a hard time finding something equivalent for 18 gauge low voltage wire. Does anyone know of any? Or know of a way to do it that would be compliant (maybe butt splices and heat shrink tubing)? I'm in Massachusetts.


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    Low voltage wiring doesn't have nearly as many restrictions as mains voltage. I'll let one of the more code-knowledgable members answer, but I don't think there's much to worry about regarding the splices.
    – JPhi1618
    Commented Oct 22, 2021 at 16:47
  • Thanks. From what I've read, the strict interpretation of the NEC code seems like low voltage is subject to the same requirements of being in an accessible j-box, but hoping I can find a code compliant connector to just remove all doubt.
    – MSmithSE
    Commented Oct 22, 2021 at 17:44

1 Answer 1


There's really no code that applies to low-voltage connections. You can generally run them where and how you like. The standards that do apply, in my opinion, are about workmanship.

I'd be satisfied with a quality wire nut or push connector and having the cable secured to framing or whatever so the connections can't be subjected to tension.

  • Cool, thanks. Yeah seems like there is a lot of debate on it. I've found a few electrician forums where they debate if the NEC code applies to low voltage or not. As it's written, seems like it does, but some argue it doesn't. As far as I'm concerned, if there's no fire hazard, which with a quality splice and my mineral wool insulation there shouldn't be, I don't care about the accessibility of it. There's probably 30 more in my walls that I don't know about already. But a product designed specifically for this would make it easier to get passed inspection.
    – MSmithSE
    Commented Oct 22, 2021 at 17:40
  • @MSmithSE, these telephone wire splices are commonly used on that small gauge low voltage wire. They are more secure than a wire nut and easier to use than some of the other splicing options. There's also "dolphin splices", that seem to be popular for this, but I've never used them.
    – JPhi1618
    Commented Oct 22, 2021 at 17:51
  • Well, you don't have to argue about it. There's a book full of written words that answers the question definitively. If everything was arguable, then the Giants won the pennant. Commented Oct 22, 2021 at 19:27
  • @MSmithSE -- the answer to that question is "only the parts of Chapter 3 explicitly pulled in by 725.3 apply to Art 725 LV wiring" Commented Oct 23, 2021 at 1:57

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