How to Change a Doorbell Transformer
Your doorbell transformer changes your 120-volt house current to either 10 volts for bells or buzzers, or 16 volts for chimes. The AC input wires connect either directly to house wiring in a junction box, such as what holds a light switch, or to a socket. The AC input wires on the transformer are black and white and come with the transformer. The output has two screw terminals with at least one wire underneath each one, and possibly two, depending on your doorbell or chimes. You must know how to find the circuit breaker that shuts off your doorbell transformer. Does this Spark an idea?
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Things You'll Need
- Doorbell transformer, either 10 or 16 volts, but the same as the one you are replacing.
- Screwdriver
- Masking tape or adhesive labels
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Instructions
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Shut off the power to your doorbell transformer. If it wires to a circuit breaker, shut it off. If it wires to a plug, unplug it.
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Disconnect the AC wiring from the transformer. If it has a plug, take the plug off and keep it. You will need it for the new transformer. You will have to figure out how to take it apart because there are several types of AC plugs. Some have screws holding it together; some just snap apart. Most have the wires connected to the prongs with screws. Loosen them and slip the wires off. If your connection is in a junction box, it is probably connected with little plastic or rubber wire nuts. Unscrew the wire nuts off the connections and pull the wires apart. Keep the wire nuts for the new transformer.
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Mark the wires from the output of the transformer. There will be two screw terminals on the opposite side of the transformer from the input AC wires. Each terminal will have at least one wire. Make a label with the masking tape and wrap it around the wire on each terminal. If there is more than one wire on either terminal, wrap the tape around all the wires on each terminal. You don't want to cross them when you connect the new transformer. Only use two labels, one for all the wires on each terminal.
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Unscrew the terminals and remove the tagged wire or group of wires from each terminal.
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Remove the transformer from whatever mounting hardware holds it in place. There could be several options, so you will have to figure out exactly how to do it yourself. But usually it has only two screws. Save any mounting hardware for the new transformer.
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Install the new transformer in the same way the old one was installed. If for some reason you can't, you need to figure out a way to mount it so that it can't be moved easily.
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Loosen the two screws on the new transformer output.
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Put the tagged wires under the terminals of the new transformer in the same positions as on the old transformer terminals. Tighten the screws.
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Connect the AC input to the wires that came on your new transformer. Either connect them to the house wires with the wire nuts or reinstall the plug you removed. To reinstall the wire nuts, twist the wires together and screw the nuts onto the connection. Reinstall the plug in reverse order of how you removed it.
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Turn your transformer back on. Either turn on the breaker or plug it in.
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Tips & Warnings
If your old transformer input connection is taped wires, you can install the new transformer the same way, but you will need new tape. Or you could buy new wire nuts.
Be sure you shut off the power before taking apart any circuits.
