The single-gang I wish was a double – and 3 other regrets

I'm standing in my finished living room, holding a smart dimmer in one hand and a multi-tool in the other. The dimmer is supposed to go in the single-gang box that's mounted exactly 48 inches off the floor, right next to the doorframe. The box is where it should be. The wiring is correct. The neutral is present. Everything is perfect – except the box is too small.

I can't fit the dimmer. Not because of the wires – I've already stuffed them in as neatly as I can. But because the dimmer's heat sink makes it a quarter-inch deeper than the box can accommodate. It sticks out. I could force it, but I know better: a dimmer that's jammed in a box runs hot, and heat kills smart switches.

So I'm cutting the wall open to replace a perfectly good single-gang box with a double. And as I'm tracing the cut line, I'm mentally counting the other things I should have done differently – the regrets that are now carved into my walls.

Here are the four that keep me up at night.

Regret #1: The single-gang I wish was a double

Let's start with the obvious one. I had the whole house open. I had 14-3 and 12-3 everywhere. I had deep boxes in most places. But for some reason – maybe it was the electrician's suggestion, maybe I was trying to save money – I spec'd single-gang boxes in a few key locations.

The living room dimmer was one. The hallway 3-way was another. And the kitchen island, where I have two separate circuits (one for the lights, one for the under-cabinet LEDs) sharing a single box? That was the worst one.

In a single-gang box, you have about 18 cubic inches to work with. A typical smart dimmer takes up 12–14 cubic inches by itself – then you add wire nuts, pigtails, the bundle of neutrals, and suddenly you're over capacity. The NEC has specific box-fill limits, and I'm certain I violated them. The inspector didn't catch it – but I did, when I couldn't close the cover plate without forcing it.

What I should have done: Specified double-gang boxes in any location where I might want more than one switch, more than one circuit, or a dimmer with a large heat sink. The cost difference is negligible. The drywall repair is not.

For future you: If you're even considering a dimmer, a smart switch, or two circuits in the same location – go double. You'll never regret having extra space. You will regret not having it.

Regret #2: The switch I placed behind the door

This one is purely about placement, not wiring. I put a three-way switch for the hallway lights on the wall that's behind the door when it's fully open. I didn't think about it during rough-in. I was focused on wire runs, not door swings. But when the door was installed and I walked into the room for the first time, I realised that to turn on the lights, I had to close the door behind me.

It's a small thing. But every time I walk into that room, I have to close the door to reach the switch. It's absurd. It's also unfixable without moving the box – which means cutting drywall, rerunning the cable, and patching.

What I should have done: During rough-in, I should have walked the job site with the door frame in place and tested the swing. I had the studs open – I could have moved the box six inches to the left and never thought about it again.

For future you: Door swings matter. Mark your switch locations after the door frames are set. Stand in the room, open the door, and see if you can reach the switch comfortably. If you're reaching around a door, move it.

Regret #3: The conduit I didn't label

You already know about my media wall from another thread. But here's a new one: I ran a conduit from the panel to the attic for future solar. It's a 1" EMT, perfectly spec'd, with a pull string. I did that part right.

What I didn't do: label it. I didn't write "SOLAR CONDUIT" on it. I didn't mark it on my wiring diagram. I didn't even take a photo of it with a note. I figured "I'll remember what it is." And for the first three months, I did. But then I ran another conduit from the panel to the garage for an EV charger. And another one from the basement to the kitchen island. And by the time I had three conduits all coming out of the panel, I had no idea which one went where.

I had to use a toner to trace each one – and even then, I wasn't sure. I ended up cutting an inspection hole in the attic just to confirm which conduit was which.

What I should have done: Labelled the conduit itself with a permanent marker or a metal tag, and recorded it in my spreadsheet. I also should have taken a photo of each conduit with a tape measure showing the distance from the panel.

For future you: Label everything. Use a label maker, a permanent marker, or a tag. Record it in a spreadsheet. Take photos. You will not remember. You are not special. Trust me.

Regret #4: The service loop I didn't leave

This one is subtle, but it hurts. I terminated all my Cat6 runs with just enough cable to reach the patch panel – maybe six inches of extra length. No service loop. No extra slack.

When I added a new switch later and needed to reorganize the patch panel, I couldn't move the cables. I was stuck with exactly where they were terminated. I had to either leave the patch panel in place (and wrestle with the cables) or re-terminate everything with new jacks. I chose the latter – and it was a pain.

A service loop of 2–3 feet would have given me the flexibility to move things around. It's not expensive. It's not hard. It just takes planning.

What I should have done: Before terminating any cable, I should have left a service loop at the patch panel end – enough to bring the panel out of the cabinet and work on it comfortably. I also should have labelled the cables before cutting them to length.

For future you: Service loops are not optional. They're insurance. Leave at least 2 feet of extra cable at both ends of every run. You will thank yourself later when you need to reposition a device or replace a damaged connector.

The regrets I've collected – and the ones I haven't yet

I've made four big mistakes. There are probably more I haven't discovered yet. I know I'm going to find a junction box that's buried behind a cabinet, or a wire that wasn't labelled, or a run that I forgot to ground.

But here's what I've learned: regret is information. It's a signal that I missed something, and it's a lesson that I can share so others don't make the same mistakes.

I'm posting this because I want you to learn from my failures. Because if I can save one person from cutting drywall to replace a single-gang box with a double, or from fumbling for a switch behind a door, or from spending an hour tracing an unlabeled conduit, then this thread is worth it.

What I'd do differently – and what I'm fixing now

I'm in the process of fixing some of these mistakes. The single-gang that should be a double? I'm cutting the wall this weekend. I've already ordered a double-gang box and a new cover plate. I'll have to patch and repaint, but that's my penance.

The switch behind the door? I'm not fixing it. It's too much work for too little gain. I'm going to live with it and treat it as a daily reminder to think about door swings in my next renovation.

The unlabelled conduit? I'm going into the attic this weekend with a label maker and a photo camera. I'll mark every conduit, take photos, and update my spreadsheet. It's not too late.

The lack of service loops? Most of those runs are already terminated, but I'm adding a small patch panel extension to give myself some flexibility. It's not a service loop, but it's a workaround.

What about you?

Now I want to hear from you. I know I'm not the only one with a "single-gang regret" or a switch behind a door.

What's your single most annoying regret from your own renovation? And more importantly, what did you do about it?

Drop your stories in the comments. Let's build a library of shared wisdom – and maybe save someone else from the same mistakes.

I'll be back to update this thread after I cut that wall open. Wish me luck. And for all that is holy, spec double-gangs.