It's not near the garage door opener or the furnace or the hot water heater. Looks like some kind of a dc transformer. The living area above it has nothing special there, just bedrooms with no special equipment.

(Hopefully the photo successfully attached, I'm doing this from my phone. )

How close are you to the Russian embassy?

The wiring looks low voltage, could it be a temperature sensor or the remains of some old alarm system?

House is brand new construction, not a single thing in the house is a remnant of anything. Every plug and switch and appliance in the house works, and is connected to something.

If it is alarm system related, it would be for the currently installed and working alarm system that was built in to the house. If so: what part is that, and what purpose does it serve?

Doorbell transformer?

I don't know why it would be in that location, though...

So it is in the ceiling, with the back side facing up into the isolation space between the ceiling and the floor of the bedroom? And only a 2-pole, thin cable? Trying to see from the pic - is it a normal 2-pole cable, or a coax/mic cable (one normal centre conductor, and one metal shield twisted into a conductor)?

What size is it? It looks kinda small, but it's hard to tell.

Looks like an AC transformer plugged into a GPO.

Very dodgy for a new house in terms of the hole in the roof.

Get up in the ceiling and follow the wire?

I'm going to vote doorbell transformer too.

Cheers

Cris

Maybe a remote phone ringer?

If you don't have a house phone that is probably why it never rang.

AC transformer... do you have a sprinkler control in the garage?

Around here, the typical place for a doorbell transformer is near/at the electrical panel. This does look like a doorbell transformer, but I'm wondering why it would be connected to a single gang work box in the ceiling. Away from anything else. And presumably with the wire routed to/via a sub-optimal location to actually get to the doorbell, which is probably not upstairs.

No matter what it is, I think the installation is a little odd. Is your electrical panel in the garage Tony?

Well, you could always try disconnecting it and see what breaks. If it's just for the doorbell, then it's easy enough to test. You might also want to get up there with a voltmeter to see whether you're likely to kill yourself or not monkeying with those wires.

Just knock it down with a shovel or broomstick.

99% likely it's a 24VAC (output) "doorbell" style of transformer, getting 120VAC input from the light socket that it directly covers.

This could be for doorbell use, or for the automatic garage door opener, or any other (?) low voltage household needs. Heating and cooling equipment also use 24VAC for control wires (thermostats) and the like. Or a furnace humidifier, central vac control wires, ..

Cheers

I agree that the location is a little odd, but, the electrical panel is located on the outer wall of the garage, so this object's location does put it half way between the front door and the electrical panel. Although the doorbell doesn't ring in the garage, it rings in the house.

Is it normal to put the transformer so far away from the doorbell itself?

My doorbell transformers have always been fairly far from the doorbell itself. The electrical panel is in the basement and the doorbell on the main level in the center of the house or close to the front door. It means a longer run of low-voltage 2 conductor cable (little copper) versus a longer run of mains voltage wire (3 conductors, 14ga, a lot more copper).

The central vac thing makes some sense too. The wire would be used for the switching and accessory power. But it still seems like an odd location/placement.

I've never seen a low-voltage garage door opener - and again the placement and wire run for this would be really odd.

Given that it's brand new, why not just call up the builder, and ask?

What fun would that be

Preposterous.

I Tony really cared about having fun with figuring out what that thing is, he'd be writing a Filk song about it.

Ah, yes, that would make sense!

I have an outlet similar to this in my attic next to my furnace. I verified that it's not the doorbell when I was last up there. My guess for mine is alarm system stuff or thermostat stuff. I didn't bother tracing the wire around the attic to see if it ended up in the furnace.

Not likely installed at time of construction. I'd go with 24vac xfmr. for doorbells, thermostats, smoke detectors, water heater control, sprinkler system.

I'll bet on sprinkler system. It's the kind of thing a homeowner will do after the home is occupied.

Newer construction around here (Portland) tends to come with a sprinkler system already installed. Ours did.