How do I make this dimmer switch work in this box? Can I?

September 15, 2023 12:36 PM

I've got a metal junction box with two light switches in it. I'm trying to upgrade these switches to new smart switches, but I'm running into a few problems....

So, I've got this metal junction box on the wall in my living room. One of the switches controls 3 ceiling lights on the left side of the room. The other switch controls 3 ceiling lights on the right side of the room.

All the lights are the same - so, why is one switch and dimmer control different from the other switch and dimmer control? No idea.

Whatever. So, I went out the other day and bought 2 HS220 smart switches.

I want to replace the two switches in there with two of these. OK!

So, next step was to go to the hardware store and buy a new face place for the junction box. This is when I ran into my first (of I'm sure many) problem.

Look at this picture! The switch is the exact height of the junction box cover, meaning that it is too tall by just about 1/8 or 1/4 of an inch at each end. It will not fit.

My obviously really bad idea was to take a Dremel and just saw off the top and bottom screw holes on the Kasa switch and put it in there and use the secondary screw holes - they seem to line up - but that seems bad.

What's the other option, though? Find a dimmer that's shorter? Get a junction box that's bigger? They seem pretty standard in size.

Why is it always something!

Anyway, welcome any advice.

posted by kbanas to Home & Garden (12 answers total)

The "junction box cover" in your photo seems a red herring. Surely the switch can be mounted in the junction box without it? The switch looks like a standard size. Maybe the metal thing in the photo was needed for whatever switch was in there because it was an odd size, but it shouldn't be needed normally. See this video.

Then you just get a 2-gang Decora-style switchplate and put that on top, it looks like the switch fits that form factor.

I suppose it is possible that you have a nonstandard junction box which you might need to replace.

Also make sure you mount the switch right-side-up rather than how you have it in the picture.
posted by kindall at 1:01 PM on September 15, 2023 [1 favorite]

Response by poster: Huh.

I had not considered that at all. I was fixated on having it fit inside a metal junction box cover. I will investigate this!
posted by kbanas at 1:10 PM on September 15, 2023

Response by poster: So, I'm still perplexed.

I popped open the junction box. Here's that picture.

I would expect screw holes where I could mount the switches, then, as you say, put a cover on them.

But there is none such! I want something like this, then, right?

The idea of taking the box out and moving it all to a new box seems a little daunting to me, frankly.
posted by kbanas at 1:40 PM on September 15, 2023

Not to be a downer, but I suspect you might have difficulty using those smart switches with a metal junction box just by virtue of the metal shielding against the RF signals used to control them, which would make the whole thing moot. An electrician would likely be able to help sort this out, but at considerable expense.
posted by Aleyn at 2:02 PM on September 15, 2023

Response by poster: Not to be a downer, but I suspect you might have difficulty using those smart switches with a metal junction box just by virtue of the metal shielding against the RF signals used to control them

I read a thread on Reddit where someone said something similar when they tried it. Damn it!

Dammnnn it!!!!!
posted by kbanas at 2:08 PM on September 15, 2023

That does look like either an old-style or nonstandard junction box where the switches mount through the switchplate holes to the front cover rather than mounting using the actual mounting lugs. Weird.

Well, since you have to replace the junction box anyway, replace it with a plastic one to make the WiFi work better. :-) Safest to have an electrician do it, but it is by no means impossible to do yourself. Just keep the wires straight. Look at it this way, at least it's not in a wall, right?
posted by kindall at 2:15 PM on September 15, 2023

Response by poster: replace it with a plastic one to make the WiFi work better

Is it safe to have a plastic box externally mounted like that? I notice they tend to be metal, mostly, when mounted externally.
posted by kbanas at 2:19 PM on September 15, 2023

Best answer: That's a standard "1900" junction box. You need a 2 gang plaster ring and any standard size switch will fit. The switch goes in from the front, rather than the back.
I can't speak to whether the metal box will shield the smart switch too much, but I think it will be fine.. rf can find its way in through the plastic front of the switch. Might have reduced range.
posted by Larry David Syndrome at 3:04 PM on September 15, 2023 [2 favorites]

Response by poster: Ok. That's EXACTLY what I want! THANK YOU!!!

Last question!! I took the cover off the junction box and it's full of wires. Like, really full. And those smart switches are DEEP. I have concerns about making them fit.

Is there the idea of a junction box that's deeper than the one I have? Or are they standard depth?
posted by kbanas at 3:13 PM on September 15, 2023

Best answer: The plaster rings are sold in different depths, that can buy you more space. You could also buy a "1900 box extension ring" - it's basically the exact same thing as your existing junction box, but with the back cut out. It screws to the existing box, you screw the plaster ring to the extension box and Bob's your uncle- easily double the depth.
posted by Larry David Syndrome at 3:20 PM on September 15, 2023 [1 favorite]

Response by poster: I love you.
posted by kbanas at 3:20 PM on September 15, 2023 [1 favorite]

Also, the kind of face plate that you have is called an “exposed work cover”, you do in fact break off the various tabs on the outlet or switch (they are actually scored to break for just this reason) and then you use the little metal dohickies that you also break off to screw into. I literally did this yesterday. I took a look at the cover, and there was a QR Code that took me to a page with lots of useful information and a couple videos.
posted by rockindata at 5:35 PM on September 15, 2023 [1 favorite]