Can a doorbell low voltage converter share another circuit's breaker by both wires plugging into it? Or should a single wire go into the breaker but split it inside the panel using a wire but? Or does it require its own whole breaker/circuit?

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  • 1
    Whatever you do, you should use a knock-out plug in that unused open hole in your breaker panel. Commented Mar 6, 2016 at 16:24

3 Answers 3


It doesn't require its own breaker because it's a low load.

A breaker terminal shouldn't have multiple wires within it. Take the doorbell out, add a pigtail, and wire nut it together.

  • I thought so. Not a big deal, i have free slots
    – amphibient
    Commented Mar 6, 2016 at 5:11
  • Well yeah, definitely if you've got a spare breaker to throw it on; that's fine too. Just know in the future that you could add it on to another circuit if you need the breaker space.
    – TFK
    Commented Mar 6, 2016 at 5:16
  • See also diy.stackexchange.com/questions/5545/…
    – Bryce
    Commented Nov 27, 2018 at 17:21

I disagree with connecting it direct to a bus... we don't use circuit breakers for normal conditions, we use them for problems, and even a small load can have a big problem.

Apologies if I'm stating the obvious, but don't put the transformer inside the service panel, low-voltage power in the same boxes, conduits, etc. as 120/240 is a code violation. Look at the threads on the right side of your picture. It's made to screw into a 1/2" knockout hole of any common steel electrical box at any convenient location, and sit outside of said box, with 24v connections made outside the box. As such, it can simply access hot, neutral and ground from the wires passing to or through said box, and thus be attached to whatever circuit breaker supports that circuit.

If the most convenient place is at the service panel, consider a common tactic done by many electricians: putting a 120v duplex outlet right next to the service panel. It would be easy to hang that transformer off the box which holds the outlet. (I suggest a 4" x 4" 2-gang box so you have ample room to work).

  • 1
    I assumed the transformer was going to be mounted in the open hole in the panel, right next to the transformer in the photo. Maybe that's a bad assumption to make.
    – Tester101
    Commented Mar 6, 2016 at 10:37
  • Couldn't tell, the transformer looks new and the hole looks old. Commented Mar 6, 2016 at 20:13

Check the breaker markings. Some breaker terminals are actually rated to accept two copper conductors. See this answer for more information. If not, you should use a pigtail.

two cu. conductors

The neutral bar terminals are likely not rated for multiple conductors, so make sure the neutral is in its own terminal.

  • How is a screw terminal made to accept two wires reliably?
    – JDługosz
    Commented Mar 6, 2016 at 14:40
  • 2
    @JDługosz I think these particular breakers use a clamping plate to retain the wires.
    – Tester101
    Commented Mar 6, 2016 at 15:22

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