I am moving into a house, and the previous owner doesn't know the answer.

Up high in the corner of the garage, the drywall was cut out to install a small transformer. The input comes from a garage outlet, and the output goes down inside the garage wall.

Transformer HD600 sec 24 V 50 VA

I unplugged it and then tested it to determine that it does not power:

  • Anything visible in the garage
  • The lights on the front of the house
  • The halogens (or anything else visible) in the adjacent room
  • Anything visible on the side of the basement near the garage
  • Broadband connection, sump, etc. (on the other side of the house)
  • Any light or appliance we use in an ordinary day

What is it for? How might I figure it out (without cutting open the wall)?

  • 4
    Possibly doorbell? Sprinkler controller? Low voltage exterior lighting? Those are the ones that immediately spring to mind.
    – TX Turner
    Dec 19, 2014 at 22:01
  • 1
    I have a similar transformer in my house, it was next to the furnace and I thought it was part of the heating system, but eventually I found that it powered the lighted house number on the front of my house.
    – Johnny
    Dec 19, 2014 at 22:05
  • 2
    Furnace is also usually 24V but those transformers tend to be at the furnace itself with a 120V line in proximity.
    – bib
    Dec 19, 2014 at 22:09
  • 1
    I see 24VAC in a house, Thermostat is what springs right to mind, way ahead of anything else. A wired doorbell would be another possibility. Other good thoughts already mentioned by others. Outside landscape light you either don't use in an ordinary day or that's all burned out and doesn't work anymore with or without power would be another thought based on the name of the company ("Gaslight conversions")
    – Ecnerwal
    Dec 19, 2014 at 22:23

1 Answer 1


Since the transformer says "Gaslight Conversions", that's a pretty strong clue that it's part of a lighting system from Gaslight Conversions, located in St Paul MN, which also matches what's written on the transformer.

If you've ruled out all of your exterior lighting, it may be leftover from a low voltage lighting system that was replaced but never fully removed.

It's also possible that the transformer has been repurposed for something else by a former homeowner, but most likely it is (or at least was) used for lighting. -- especially since that company sells their transformer for $40, but you can pick up a generic 24VAC transformer from Home Depot for $10 - $15, so why buy the name brand if not for use with their lighting products?

If it plugs in (as opposed to being hardwired), that makes it less likely that it powers any permanently installed equipment like a doorbell or furnace.

  • 5
    +1 This nonsense with looking at the pictures and reading the obvious has got to stop!
    – bib
    Dec 19, 2014 at 22:30
  • 1
    Ha, I ignored the writing at first since it was washed out by the flash, but as soon as I made out the word "Gaslight", I figured it was from a lighting system and got lucky with a google search - I was surprised that a company with a name like Gaslight Conversions was still around since it's been many years since I've seen a real gas lamp that wasn't purely decorative.
    – Johnny
    Dec 19, 2014 at 22:34
  • D'oh! I assumed the company name was a fanciful but meaningless anachronism. Although the lights attached to the house are running, the lamppost in the yard is dark. I'll go find out if you're correct.
    – Foo Bar
    Dec 20, 2014 at 1:31
  • @Johnny - you should go check out the French Quarter in New Orleans - loads of gaslights running there :)
    – warren
    Dec 23, 2014 at 19:32

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