How to wire/install first doorbell transformer in old house

[Eric M]

I want to add a ("smart") doorbell to my house which was built in the 60s without a doorbell (back when knocking was good enough). There is a 2-gang switch box by the door (controlling the exterior and interior entryway fixtures).

My thought is to tap the power from the switch box (where there is neutral and hot), feed 110v up the wall to a new junction box (near the ceiling) and mount a transfer in that box (like the NuTone C915) with a blank plate cover, then run the low voltage output back down the interior of the wall and thru the exterior wall to power the doorbell.

Does this seem like the appropriate approach? Is there a better way?

 

[Stuff]

Wiring 120v to a C915 is a good solution. You will need a matching dual voltage electrical box like https://www.lowes.com/pd/CARLON-2-G...ard-Switch-Outlet-Wall-Electrical-Box/3286108 as the low voltage cables come out the front of the transformer.

Why not also install a physical chime? Mount it to cover the transformer. A big reason is that some smart doorbells shorten the transformer's life without one (gives a resistor/load so can't fully short out).