Doorbell transformer blown days after replacement, now what?
Moved into a new house some months ago - doorbell ("smart" doorbell with camera) died a few weeks ago.
The doorbell install looks DIY: There's 22AWG wire run from the doorbell transformer through a basement window, along/tucked under the shingle siding, up through the wood porch and up to the doorbell (i.e. nearly all of which is exposed to the bitter Northeast USA elements -- and the 22AWG wire doesn't look like it's rated for exterior use...).
When the doorbell broke initially, I measured 0V across the 20V terminals of the doorbell transformer, 120V with proper ground going into the transformer... we just had a heat pump put it so I figured they may have accidentally shorted it or something (bit of a stretch, but couldn't think of any other changes) and didn't think twice... swapped it with a 24V transformer from the hardware store and was back up.
Well, the (new) transformer also blew about a week in service. 0V across the 24V terminals, power to the transformer.
Now I'm wondering WTF do I do? What could cause a not-immediate but sufficiently delayed (1 week) short like this? Should I redo the wiring, replace the doorbell, both? If I rerun the wire with something that's rated for outdoor use, I can DIY the outdoor run myself... really don't want to open the wall and fish wire if I can help it but I will if it's too stupid or against code to run it outside like it is now in most municipalities.