I have an old-school intercom installed in the house that I am in the process of disconnecting. When I remove the master unit from the wall, I found 120v mains coming in directly to a transformer behind the unit, with absolutely no separation between the HV and the LV side (and all the wires to the various head units).
Given that I'm pulling the system out, I don't mind, as ultimately I'm going to put the 120v wire into a junction box and add a doorbell transformer into the cavity left by the master unit.
I'm having a hard time locating the breaker though. It isn't the light or outlet breakers that are near by in the kitchen, and it's un-labeled. There are a lot of breakers, so ideally I'd like to avoid going one-by-one. There is a 60-htz hum coming from it and my non-contact voltage detector confirms it is hot.
Is there an easier way to determine which breaker it's on than just trial-and-error for all of them? If there was an outlet, I'd use a tracer to find the breaker. But given this just goes into a pair of wire nuts and then the transformer, I don't want to touch it while live...