Locating Doorbell Transformer


Old 11-12-12, 08:48 PM
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Question Locating Doorbell Transformer


I am a do-it-yourselfer with no professional electrical experience. That being said, I do have experience with installing and wiring switches and light fixtures around the house - the easy stuff.

My current DIY challenge is trying to fix the doorbell on a 1965 house. There are two doorbell buttons on different parts of the exterior, both of which appear to be original. The wiring going to each of these buttons also looks original (old).

On the inside of the house there are two separate doorbell chime boxes, each of which is located relatively close to their respective exterior buttons. The wiring going to the chime boxes is "different", leading me to believe that it is not configured as a straight shot from the button to the chime - in other words, there is likely a transformer in the middle.

My issue has been in locating the transformer or transformers. First of all, I am not sure if these two doorbell button and chime pairs would share a single transformer, or if they each have their own transformer. I assume if there was a single transformer then it would be centrally located between the two doorbells. However, if we are dealing with two separate transformers then they should each be in the same vicinity as their respective doorbell hardware.

I have so far checked any obvious interior locations, I have checked the electrical panel outside, and I have checked through the attic of the house. When in the attic, I checked the beams and rafters for a mounted transformer but I did not yet start pulling up insulation. So far, no luck in finding the transformer(s). Any suggestions here would be much appreciated.

Also, another reason I believe there is a transformer is because the voltage measured on the wires going to the chime measured between 1.5v and 2v. As an amateur DIYer, I can only conclude that this means there is a failing transformer somewhere on the circuit which is pushing out a voltage too low to power the chimes.

I would appreciate any advice or suggestions anyone here can provide me.

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Old 11-12-12, 09:07 PM
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Wow.....good luck. I can't tell you how many times I (as an electrician) was callled in to fix a doorbell. Usually one transformer for the system. Where is it. Anywhere your imagination deems possible. Usually it's in the basement but I've found them everywhere and very rarely mounted to the electrical panel. The volt or two you are measuring is probably a phantom or induced voltage. For the most part those transformers put out their full voltage or nothing.
Old 11-12-12, 09:24 PM
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Interesting, thanks for the input. Could well be a phantom voltage.

In my case, I have no basement so that rules that out. I figured the next logical place would be the attic, but didn't find anything in an obvious place up there. Where else could it be? I'm hoping it's not inside a wall somewhere. Assuming there is only one transformer, it could be anywhere.
Old 11-12-12, 11:59 PM
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Yes....I have seen them in walls. No basement.......ok. Where is the panel ? Surface mounted panel and you would see transformer. Recessed panel......could be on side in wall. Open panel up to look for it. Any closets with lights ? Especially pull chain lights. Crawlspace ?
Old 11-13-12, 11:20 AM
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The electrical panel is on an exterior wall of the house, recessed. I have not yet opened up the electrical panel to look inside, so I will give that a shot.

I can think of at least 4 closets with pull-chain lights, so I will revisit those closets and pay closer attention. A friend also suggested I look inside the kitchen cabinets, so I will give that a shot once I get home from work.

Luckily no crawlspace, as the house is on slab and the entire ground floor is all brick flooring.
Old 11-13-12, 11:39 AM
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If you are getting only 1 or two volts then the the transformers are probably dead. Did you use a digital multimeter? Best to use an analog meter.

the voltage measured on the wires going to the chime measured between 1.5v and 2v.
Was that measurement made between the common wire and the front door terminal wires with the wires disconnected from the chime and the the wires to the chime switch at the door connected together? If not try again doing it that way.*

If you can actually get a voltage reading for the transformer you may be able to narrow down its location by turning off each 15a and 20a single pole breaker till you find which one cuts power to the transformer then determining what area of the house has also lost power with that breaker off.

*The other chime may need to be disconnected to get an accurate reading if it is a shared transformer. If there are more then two wires at either chime the additional steps may be needed to test.
Old 11-13-12, 11:50 AM
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I too have no basement and found the transformer mounted to the cabinet under the kitchen's sink.
Old 11-13-12, 06:11 PM
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I can think of at least 4 closets with pull-chain lights
And do these pull chain lights have bare bulbs? In other words, if these are porcelain pull chain lights they are a code violation being in your closets, you need fixtures with glass globes. This can be your next project to correct this. Meanwhile, check your attic again with a good light and look under ALL of the insulation, my guess is this is where you'll find the chime transformer.

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