Electrical Wiring Question: Hooking up a second door bell

I often work in a basement office, but can’t always hear the doorbell. I’d like to hook up a second door chime, so that when a visitor pushes the doorbell at the front door, both the 1st and 2nd floor door chimes sound. I also want a wired, rather than wireless, system, as I don’t want 2 doorbells at the front door and don’t want to add a “slave” wireless system.

Problem is, I can’t figure out the wiring. Currently, it looks like the sheated two-wire bell wiring has 1 red and 1 white wires. The red wire from the front door runs to the basement, where it connects with a 16 volt transformer attached to the power supply at a ceiling light. The red wire from the chime runs to the other transformer connector. In short, 2 red wires are connected to the 2 connectors on the transformer. (By the way, I think the existing transformer is 16 volt. I bought a larger transformer, but an electrical guy at Home Depot said my current one should work fine.)

I experimented and tried running a wire from BOTH transformer contacts to each of the second chime unit, but when I attached one of these new bell wires, the second chime kept chiming and chiming. I then connected only 1 wire between the transformer and second chime–and switched wires to see which worked.

None did.

>>> Do I run 1 or 2 wires from the transformer to the second chime?

You have to run a wire from the transformer to your second chime, and a branch off the white wire from the bell to your second chime. That will wire your two chimes in parallel. The wire to the transformer should go to the same transformer contact as the red wire from your first chime.

It may be possible to wire your chimes in series - unhook one of the red wires from your transformer, hook it to your new chime, and run a wire from the 2nd contact of your new chime to the transformer where you unhooked the red wire. It probably won’t work, but it can’t hurt to try and it’ll save you some wiring if it does.

Determining which is the easiest wire pull is difficult as it’s driven by so many factors. Since you’ve said you’re working in a basement office, and door chimes are typically located in a center hallway of the first floor, I’d be inclined to drop another piece of red/white down from the existing chime into the basement, and match colors, putting the second chime in parallel with the first. If you can’t put both wires on the screw terminals of the first chime easily, cut a short jumper and wirenut (small blue or orange) three pieces of wire together, and place one under the terminal screw. If this fails to make sense, send me an email and I’ll prepare a drawing for you. Good luck.

As matt said, one from the transformer, one from the button.

Think of it this way. The same two wires that go to the existing bell/chime need to go to the new bell/chime.

So going to the existing bell/chime you’ve got one wire coming from the transformer. This same wire also needs to go to one terminal on the new chime. It doesn’t matter if you tap it off the transformer end of the wire or the chime/bell end of the wire, electrically they are identical. Make your connection on the end that makes it easiest for you.

The other wire going to the existing chime/bell comes from the button. Again, this same wire also needs to go to the new chime/bell. And again, it doesn’t matter which end of that wire you tap in to, pick the one that’s simple for you.

A few things to be sure of:

1-Both chimes should use the same voltage.
2-You existing transformer needs to have enough amperage capacity to run both chimes. This is not the voltage, it’s usually shown as a VA (volt/amps) or wattage rating.
3-Your existing doorbell button should be capable of handling the extra load (amperage, not voltage)
4-Any wires that share the load should also be rated for the increased load (again, amperage, not voltage).

I’d bet the only one you might have to worry about is number 2. I’ve seen some pretty small doorbell transformers over the years, and they are sometimes sized right at the edge for amperage. The others items are almost certainly OK, but it can’t hurt to check.

I can only access the button wires. Can I put another door bell in series with the button and then put in a 24 volt transformer to operater both bells together? This should then make about 12 volts for each bell or about half of the transformer voltage. Power is not a problem as doubling the voltage will provide the same power to both bells. But different style door bells could be a problem.

I can get to the transformer to replace it but not any of the other wiring other than the 2 wires in the attic that go to the button. I want to add a bell in an adjoining room to the attic. I cannot run any wires down the wall to the existing door bell and transformer.

Maybe one could put a relay in series with the button and then the relay could act as a second button for another bell and transformer. But what type relay does one need - AC or DC coil and what resistance.


from the bell in the attic, run two wires to where you have the second bell in the attic. attach the two wires to both bells without changing the wires to the existing bell.