So this question could be a dumb one, as I have little to no experience with electricity. Anyways, here it is:
My current project is using the RPi Official Touchscreen (7 inches), along with a RPi3 and putting it in my wall where an old Nutone intercom (Nutone IS408) used to be. The intercom has various wires, which I'm assuming some of them carry power for the speaker. These wires come from the main unit downstairs, which is a Nutone IMA-4006. Would it be possible to connect these wires to somehow power the RPi3 and RPi Touchscreen by connecting those wires to the Pi somehow? Whether it's through the GPIO Pins, or splicing into a Micro-USB cable?
I want to do this because there is no easily-reachable power outlet near this wall, and this being able to use those existing wires would probably be ideal if it's possible.