A conventional doorbell or chime is wired to your home’s 120-volts electrical supply, which a transformer steps down to its required voltage between 6 to 24 volts. Older doorbell systems used to operate on 6 or 8 volts AC while newer models require a step-down transformer at 12 to 14 VAC and at 16 or 24 volts for door chimes.
So before performing any maintenance on your system, the circuit breaker has to be turned off to prevent the risk of electric shock. The doorbell transformer, however, is not normally wired to its own dedicated circuit breaker, but rather with an already existing receptacle, light switch, or another junction box nearby, and supplying a completely different circuit, so it will not likely be identified inside the electrical breaker panel. By following the instructions that follow, you will be able to find the right breaker without too much hassle.
Step 1 - Locate the Doorbell/Chime
The first thing to do will be finding the transformer that powers the doorbell/chime. The way to do this is to track it by following its low voltage wiring leading from the doorbell/chime.
1.1—If it’s hard-wired to the push-buttons, look around the area at the main entrance to the house for the doorbell/chime itself. It could be exposed on a wall surface if it has a nice finished appearance, or concealed—not hidden—behind a wall or inside a closet near the entrance area but from where it can be heard clearly. Figure 1 shows an example of a chime concealed behind a wall hidden from view but at a reasonable audible distance.
1.2—If you’re dealing with wireless push button, it will offer an infinite number of option to the doorbell/chime installation, but keep in mind that it’s there to be heard, it should be located in a widely used room such as the kitchen, living room area, den or elsewhere, and as mentioned previously, it could be concealed.
Step 2 - Tracking Back to the Transformer
2.1—Regardless of the system, the transformer will most likely be closeby as it needs hard-wiring to the doorbell/chime in order to power it (Figure 2).
If the wiring is exposed, it will make locating the transformer much easier. If the wire goes through the wall to the opposite room or inside a closet, it should be again easy enough to follow to the transformer. If it’s inside a wall, however, it will either go down to the basement where the wiring from dozens of circuits offers great hook-up opportunities or up to the attic secured under a joist or hidden beneath insulation but you need to look for an electrical box since it will probably be within reach of its 120 V supply wires. Figure 3 shows a transformer wired-in to an added junction box that is tapping from an outlet closeby and in this case, visible from the other side of the wall.
2.2—At this point, you’re now looking for a circuit breaker feeding or dedicated to a whole circuit and most likely identified inside the breaker panel. Shut off the breaker and proceed to do your required maintenance. But if that circuit is not readily identified, you’ll need to keep searching.
2.3—If there is a light fixture closeby, turn it on, and with the help of someone else to tell when the light will go off, test each 120 volts circuit breakers to find the one that will turn off the fixture.
2.4—If the circuit feeds a receptacle nearby, a Circuit Breaker Finder with the sender plugged into the receptacle, the right breaker can easily be identified by scanning the receiver probe in front of it in the breaker panel (Figure 4 & 5).
As the probe approaches the right breaker, the light will flash more rapidly (Figure 5) and the beeping frequency will increase. The CB Finder can be a very practical tool for under $35, for any DIYers doing frequent electrical work.