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I bought a house recently. Some of the wiring, particularly in the basement, while not obviously unsafe, is... inspired.

On the side of a junction box in the basement, there's a device with two thin wires coming off of it, going up into a hole. I believe, but don't know for sure, that above the hole is an exterior wall, but there's nothing on that wall that would use such thin wires - just switches and outlets, which I'd hope are fed from the thicker cables also going through that hole.

So what is this thing?

Emily
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    Does this answer your question? [What is this thing on my junction box?](https://diy.stackexchange.com/questions/123531/what-is-this-thing-on-my-junction-box) – Peter Duniho Jul 27 '20 at 20:00
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    Is it making a mysterious ticking sound? https://www.youtube.com/watch?v=RT0zB47mPfc – Valorum Jul 27 '20 at 20:47

4 Answers4

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Looks like a doorbell transformer. Prolly output is 24 V ac from input 120 V ac in the metal box.

Jim Stewart
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    +1, voltage and VA (volt-ampere or watts) should be marked on transformer, could also be 10v or 16v. – NoSparksPlease Jul 27 '20 at 03:42
  • That would make sense; I think the front door is near there, and there's also an unused doorbell chime elsewhere in the house. It seems like they used to have a doorbell and removed it at some point. – Emily Jul 27 '20 at 04:40
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    It should probably be secured to that joist to prevent strain on the wires. – Ben Jul 27 '20 at 12:57
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    @Ben It looks similar to one I've got in my basement; the transformer is probably mounted in one of the knockouts in the handy-box (which also serves to connect the 120V to the transformer within an enclosure). – Joshua Taylor Jul 27 '20 at 13:44
  • @Ben Assuming those wires are even still connected to anything, which from the description it sounds like they aren't. Might be better to just remove them, unless you're planning on installing a doorbell yourself at some point. – Darrel Hoffman Jul 27 '20 at 14:05
  • I have one of these supplying low voltage to the furnace, so a doorbell is not the only possibility. – mustaccio Jul 27 '20 at 14:27
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    @mustaccio with the wires going up through an exterior wall, I think it's very safe to assume it's not going to his furnace. – Jeremy Jul 27 '20 at 15:31
  • @JoshuaTaylor, I don't see how it would be mounted to the box. I suspect that the high voltage wires connected to the transformer are holding it up. If there's no grommet on the punch out, that could cause wear on the wire insulation which is bad. Ideally, the wire would go through a grommet or better yet a cable clamp. That's why I would suggest mounting to the transformer to the joist. Maybe I'm wrong. – Ben Jul 27 '20 at 19:11
  • @DarrelHoffman, what part of the description leads you to believe that it's not connected to anything? I thought OP just wasn't sure what it's connected to or might be used for. – Ben Jul 27 '20 at 19:13
  • @Ben The comment from the OP in this answer, 2nd from the top. Obviously you'd want to check it before removing. Depending on the age of the house, though, it's not uncommon to see things like this hanging around that aren't of any use anymore. – Darrel Hoffman Jul 27 '20 at 19:16
  • "Prolly" OMG, Ima Tryna process that one. – Alaska Man Jul 27 '20 at 20:24
  • @DarrelHoffman, maybe I misunderstand, but it sounds like there are two doorbells and this is for the one that is still active while there is another that is no longer in use. Yes, this is an assumption on my part. Maybe the first course of action should be to the test the high side of the transformer for voltage. – Ben Jul 27 '20 at 20:55
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    @Ben Here's an image of how mine is mounted: https://imgur.com/a/AV5AvCr . The transformer has a tab and a screw to secure it in a knockout in the handy box. That knockout is also how the transformer's 120V leads get *into* the handy box so they can be connected within an enclosure. Searching around online, other transformers appear to use similar approaches, e.g., https://m.media-amazon.com/images/I/616WxQiy-+L._AC_SS350_.jpg appears to have a threaded tube to fit into a knockout. – Joshua Taylor Jul 28 '20 at 19:57
  • @Ben Ah, and to keep things within the stack exchange network, here's a question on DIY about mounting transformers, and the comments on the accepted answer even include, "the ... nut on the inside provides the support. the screw tabs are only used if you don't use the finger nut." https://diy.stackexchange.com/q/86038/23007 – Joshua Taylor Jul 28 '20 at 20:16
  • Since people were speculating: this is unused wiring for a wired doorbell; the previous owners had a Ring doorbell which they removed and replaced with a wireless doorbell when they moved out. The junction box it's attached to is part of a live circuit which also powers some nearby outlets. – Emily Jul 30 '20 at 04:58
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About 40 years ago, I saw a similar transformer in our basement. I asked my father what it was, and he thought doorbell. We disconnected a wire and the bell still worked. That night, my mom went to make a phone call and the phone dial wasn't lit.

In the old days, mid-late 70's, 4 wires to the phone. Red/Green were the phone service, the other 2 lit up the dial. Sometime later, the current in the phone line itself was enough to light the dial, and the 4 conductor wire was useful to run two phone lines.

JTP - Apologise to Monica
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There is a slim chance that this is electric osmotic damp treatment. You might see a couple of electrodes on the wall. We had this in a house we moved into in about 1977, we disconnected it and cured the damp by unblocking the gutter...

Rich Farmbrough
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    It looks like a timber framed building. Electro-osmotic damp protection is for masonry construction. – J... Jul 27 '20 at 16:10
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I saw one of those things in my basement as well, and I can confirm that it is a doorbell transformer. If you want, you can get a multimeter and put the two leads on the two screws on the top. It should show a low amount of voltage ≈20-40VAC.

Rick Yao
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