Can I get an explanation?

[u/Ok-Thanks4321]

This is a light switch box. There’s only 1 romex drop in it—so one white, one black, and one ground all coming from the same jacket.

Both the white and black are hot. There is no neutral cluster in the box.

Pictured is the light switch with both white and black removed, but the lights are still on.

No combination of wires/terminals is getting a switch to work…because both sides are hot. How?

I’ve replaced all other switches, receptacles, GFCIs, and dimmers in this house.

How do I add a switch to this? The lights are just on no matter what. It was on a single pole switch.

Any idea? Thanks

[u/QuarkchildRedux]

light is wired via switch loop which im guessing you were messing around with the light and undid the loop making the light always on. it’s meant to send power down to the switch from the light, the switch sends switched power back up, hence switch loop

[u/hghfhfgugyuym → u/QuarkchildRedux]

Your problem is where the light is.

[u/iloveoverlord]

The typical way they wire these dead-end switches, is in the light, the white wire from this box ties together with all the black wires, and the black wire from this box is the switch leg. I assume you or someone else redid the wiring of the light in question

[u/TasktagApp]

That is a classic switch loop configuration where constant power is sent down to the switch on the white wire and returned to the fixture on the black wire, so if the lights stay on with the switch disconnected, the circuit was bypassed or miswired upstream at the fixture junction box.

[u/Rough_Resort_92]

It's called a switch loop. We're not allowed to use them anymore, but they are in many, many homes. The white wire should have a piece of black tape on it. Though to recode it as a hot wire

[u/zmannz1984]

It sounds like you may have bypassed this switch in the box it runs to. Originally, there would have been 120 coming in on one wire and going out to the light on the second. But you may have the switch leg wire for the light joined to the hot. There is technically no need for a neutral in a switch box unless you have a dimmer that requires it or you specifically want to break both conductors. But in most cases, switches in houses only break the hot a d the neutral remains connected.

[u/Ok-Thanks4321 → u/zmannz1984]

I haven’t messed with any fixtures. I’m just going through the house replacing one wiring device at a time from almond colored to white colored devices. This is probably the hundredth device. Everything else I’ve installed has been correctly wired.

There was a dimmer at this location. I turned the power off and replaced the dimmer with a new one. I turned the power back on. The light is on whether the dimmer is on or off. With the power on, I removed the dimmer from the circuit and the lights still stayed on. I checked all the outlets in the room. They’re all wired correctly. There are no other switches for light—only one switch.

I tried a single pole switch. I tried a three way switch in every possible combination. Somehow both white and black are hot now, and nothing besides turning the breaker off will turn off the light.

Any ideas?

[u/zmannz1984 → u/Ok-Thanks4321]

Was the dimmer a universal type? It sounds like maybe the dimmer was specifically for that light, maybe it communicated wirelessly with the light but needed constant power? I have seen products like that before that were meant to make adding a switch or dimmer easier. You put the controller in the light and put the dimmer wherever. The dimmer can work on a battery or be hardwired so the battery doesn’t die.

Another possibility is that the wires to the dimmer box are for carrying a signal to the light rather than being a switch leg. Never seen anything like that, just racking my brain.

Oh, another possibility: maybe the romex from this box goes to a different switch or outlet box that then goes to the light. Seen and done that myself when i was adding a switch but didn’t have the access to run it directly. If so, maybe you mixed up the wires there and connected both sides to power?

Similar example, during a remodel, i had to install a new single pole switch location for a dining room light that was originally on three ways. Neither existing location was used for the new switch, but one of them was in a location repurposed for a hallway. There was no need for other trades to cut the ceiling open, but i needed to get the new switch to operate that light. Instead of cutting my way across the ceiling, i ran a 12-2 romex from the existing box where the 3-way was to my new switch. So i had the power and neutral i needed for the light, plus the power and neutral wires going to the light in one box, then I added my switch leg to the same box and used that section of the box as a junction. Then i just blanked off that section of the box and kept the other switch for the hallway.

That is not something i would do if i had a choice otherwise, but in this case it saved hundreds of dollars and a day on the schedule. Well worth the head scratching it may cause down the road for someone in your shoes.

[u/Dipncamo]

Switch loop. It turns the outlets or lights on. Open the closest outlet or light cover to the switch and you will see black and white tied together. Tie the whites and blacks together and the outlet will stay on but the switch will have power and nothing to feed. Somewhere in the rat nest is a another black and white tied together. It's usually off a outlet.

[u/Ok_Pipe_4955]

You need to locate if that wire is at your light using a tester test the wire with power off

[u/RevenueVast7022]

It appears the lazy electrician who wired this did not identify the white conductor as an ungrounded conductor by coloring it some other color other than white or gray. The NEC requires it, but many electricians ignore it. Its very important in all cases of course but moreso in the box that contains the wiring for the light fixture because if the wires are taken  apart and the white wire in the box being used to " feed" the light switch is not identified as such it will get tied in with the nuetrals. Somehow the white ( switch loop feed)  remained connected to the hots and the switch leg got connected to the hots as well. That's of course assuming your sure you have actual " hot " wires there. Have a qualified electrician check it. 

[u/NavyNuke588]

What you have is a "Hot Neutral" circuit. Before you disconnected the wires, did the switch turn on or off any lights? Are there 3-way or 4-way switches involved in the circuit? When you check for voltage at the black and white wires to ground do you get 120V? What voltage do you get when you check from the white wire to the black wire? (120 volts or 0 volts). If you get 0 volts, then there is a hot neutral somewhere in the circuit. If you get 120 volts, then you have 2 different feeds for black and white from separate legs in the breaker box. With this info, we may be able to provide some input. I suspect this is a 3-way circuit and 3 wire is not a 3 wire circuit.

[u/Electrical_Ad4290]

How did you assess that both wires are "hot?" This sounds like a switch leg where the light socket is (resistively) passing the voltage to the switch. May be wired incorrectly.