Does your house have a mystery switch?

Yes. It presents itself as a 3-way switch in a short hallway. If you throw it, all it does it turn the power off to the switch at the other end of the hallway. Since the hallway is about 10 feet long, we've never cared enough to find out why. Well, I'm pretty sure because it's wired wrong, but I can't care enough to fix it.

It does trip up the occasional guest / repair person, though. 

so, when we moved in to our house, there was a hole "punched" through the two layers of drywall from the "laundry closet" to the garage, where a manual fuse box (like with the big side handle throwing deal) hung on a nail on the wall with a 220V plug.  The other end hung loose to plug into the dryer's outlet.  That whole boondoggle is gone now, and drywall fixed.

further, in that garage, there are two switches one by the door into the house, and the other on the far opposite side by the roll-up garage door, that do nothing.  That outlet by the door into the house has a vertical switch (one of the ones that does nothing), an outlet, and a horizontal switch above the switch and the outlet.  The horizontal switch controls nearly all power to the garage... except I think the garage door, and two outlets up near the ceiling of the garage that I think are run on the same circuit as the garage door.  So, four "normal level outlets", the overhead light (with a pull switch), the garage attic fan, the lights in the garage attic (which also have a separate switch in the attic, but it's in series), and two exterior lights... all controlled by the one horizontal switch.

Also, there's a square button in the kitchen that is sort of orange, and I assume used to light up.  It's next to where the sole-house rotary phone was mounted to the wall (I'm guessing, but pretty confident based on the jack-plate).  I guess that square button could have been an intercom button... but it's right in front of a window that looks out kinda on the front stoop... so, probably not?

And the light for the front stoop is some kind of ouji-knob contraption that push-clicks for on/off/set/timer... and turn the dial to set the timer... got it to work close enough, nobody touch that ever again!

In reply to ShawnG :

That sounds like a classic miswiring of the travelers and you shouldn't need to open the wall. There should be a three wire cable between the two boxes and they just didn't land the wires properly at one end. Easy fix.  Typically there are two similar color screws on the switch,  try switching the two wires connected to the same color screws at the end that has to be ON for the other to work. Turn the circuit off before trying so you Don get zapped. 

Knurled. said:

No mystery switch, but when I went to replace the switch for the kitchen sink light, I found that the kitchen apparently does not go through the breaker box... or the auxiliary box next to it.... or a mystery fuse box in the basement bathroom.

 

So I replaced the switch live.  Be nice to know where the fuse/breaker is for future reference, though.

 

House is full of stuff like that.  The main floor's bathroom sink drain was just some random pieces of pipe loosely pushed into themselves, as I discovered when I removed the J-trap and the stuff in the wall sort of fell into the basement.

It has to be fused by something. Keep checking, it doesn't get powered by magic. 

Rodan said:

Yup, three switch panel in the master bedroom.  One for the ceiling fan, one for light, the other one...???  I always assumed it was just an extra and unwired.  I have another right next to me as I type this in the family room.  No idea...

Most likely for a light kit on the fan for the future. 

Most unknown switches I have found control an outlet. 

There was a switchplate in my apartment with three switches that did nothing.  One day I tried to see what was wrong with it and found it was just glued to the wall to cover a fist shaped hole.

In reply to imgon :

Could be. 

Truthfully, I'm lazy, the tenant doesn't complain and it hasn't bothered me enough in 8 years to deal with it.

It will probably be fixed when I decide to sell the house. 

Not so much a mystery since I know what it does but mysterious to those that don't.... 

In my kitchen to hallway transition I have a switch much like this: 

Odd in itself with the sideways toggle covered in what looks more like an outlet cover plate and also the red light.  Furthermore, the switch is about 6 ft off the floor. 

 If you throw the switch, the red light comes on. It's function is to kill all power to my two garage door openers. 

My house was built as a summer home so considering it would be empty often, the house has some elaborate security for its time (1973 build). 

We had that mystery at the store today. A 20 amp slim two switch blows with a power outage. Upper switch will stay on, lower kicks out. Everything In the guys house works fine. 

Yep, two switch box between the back door and kitchen. One switch works the outside light, the other one is a mystery.  House built in 92, we've been here since...01 maybe? Still no idea.

My first house was a new build. Next to the front door was a switch panel that had 4 switches, one for the porch light, one that controlled an outlet next to the door, one for the ceiling fan and one mystery. Did figure it out though, went to the ceiling fan to install a light on the fan that was never installed.

Current house doesn't have any mystery switches but does have a couple odd things. First thing I found when moving in was a phone jack that didn't work. Found out that it was never wired. The other thing that is a mystery is a 220v outlet in the master bedroom on the inside wall farthest from the window right next to a standard outlet so that leaves out window AC unit. Neighbor joked about it and the first owner, a single woman that had a lot of "house guests". Joke was for possibly industrial toys. I'm the third owner. I think I've figured out that it was most likely for a waterbed heater. House built in the 80's and some waterbeds had 220v heaters.

wlkelley3 said:

Neighbor joked about it and the first owner, a single woman that had a lot of "house guests". Joke was for possibly industrial toys. I'm the third owner. I think I've figured out that it was most likely for a waterbed heater. House built in the 80's and some waterbeds had 220v heaters.

Sadly, that was the first joke I thought of too....

Waterbed heaters always seemed like such a bad idea to me....here, lay on this bag of water while it's plugged in to major current....

Pete Gossett said:

When we closed on our house the POs actually said “Good luck figuring out the electrical.”

I wish I'd received the same warning.  Although the PO had intended to convert the heating to electric (currently oil) and had a 200A service installed - bearing in mind, the house is all of 600 sqr ft and my electric bill rarely goes over $100/mo. 

The joys of having a house built in the 30's during prohibition that was never really intended for full-time occupation. The electrical is a hodge-podge of wiring of various eras and very little of it would meet current Code.  I don't really have "mystery" switches, but I do have a number of switches and outlets that don't work anymore. I have a dream of gutting the entire house down to the studs and completely replacing the wiring and devices. Someday...  the plumbing is a bit of a kludge as well. And the framing. And the (lack of) insulation.

In reply to John Welsh :

I installed a couple of switches like that in my ex's house for the basement light and the garage attic light, so you can tell from a glance if they were accidentally left on.

Whoever put the switch that cuts the power to all the plugs in the living room right next to the switch that cuts on and off the living room light.....bastard

Hmmm... I think I do have one mystery switch, actually. In our bedroom, it is on a wall not near a door, near a 2-bank outlet that was oddly placed and a 4 bank outlet that was, again, oddly placed. I don't think the switch controls any of them, it doesn't control the light on the fan, and it doesn't control any lights outside. Now that I think about it, it might control our whole-house fan, but you actually turn the fan on/off with a remote, so it would only control power to the fan, not the fan itself. 

I did have one in the basement that I couldn't figure out for forever. Controls the outdoor lights on the garage. Very odd place for such a switch. Also have an oddly placed switch in the family room that controls a single outlet in a bank of 4 outlets; we leave it turned off because it makes a small buzz when on. Probably because it is a slider switch, which is just weird for an outlet. 

The house I currently live in had a mystery switch next to the sink, right next to the garbage disposal switch.  I couldn't figure out what it controlled so I just left it off, thinking it was a spare for the possibility of a light above the sink or under cabinet lighting or something.  Coincidentally around that time my dishwasher stopped working.  I spent a month washing dishes by hand while I tried to diagnose the dishwasher.  Eventually a friend pointed out that switched dishwasher power is a common thing around here.  I am not a smart man.

Slammo said:

The house I currently live in had a mystery switch next to the sink, right next to the garbage disposal switch.  I couldn't figure out what it controlled so I just left it off, thinking it was a spare for the possibility of a light above the sink or under cabinet lighting or something.  Coincidentally around that time my dishwasher stopped working.  I spent a month washing dishes by hand while I tried to diagnose the dishwasher.  Eventually a friend pointed out that switched dishwasher power is a common thing around here.  I am not a smart man.

"Switched dishwasher power"--I've never heard of it, but after the Great Dishwasher Fire of '19, I'd be happy to have had one of those instead of running down the stairs and searching for the right breaker

We built our house in 2004, I designed it so if there are any mystery switches they are well hidden. 

We've had a few and figured that it was just part of our home's charm. Then I asked the electrician while he was over.

First one: We had a switch in the bedroom that controlled the bathroom light.

He said that made no sense, so he took a peek inside. Turns out that someone screwed up the wiring. That switch was supposed to control an outlet to be used for a lamp. He fixed.

Second one: We also had a switch near the front door that seemed to do nothing. That also, we learned, controls an outlet for the same reason. 

We sold a house last year with a mystery switch that still kinda bothers me wondering what it does.  Was next to the window near the bed. Didn't control any outlets or outside lights as seemed logical.  Previous owner had tried to figure it out with no luck. There was also a mystery junction box in the basement that could have been related but I never got around to ringing it out.  Would have loved to hook the mystery switch to something stupid, just for fun.   Hope the new owners figure it out.  Would be great to send them a letter with just that question.

Our house started big when built in 1954 and then was added on to to become enormous. There are switches everywhere, most of which I've worked out. There are 5-gang banks of switches in at least two places. One 4-gang bank had a post-it note on it that said "what does this switch do?" when we moved in, and since we couldn't figure it out either we just left it. 4 years later the post-it fell off and wasn't sticky enough to stay up any more so it got tossed. We still don't know what the switch does.

In reply to David S. Wallens :

My house has a similar wiring hack. At some point, someone decided they wanted a light in one of the bedroom closets. So they apparently went into the attic and tapped into the nearest wiring they could find, which happened to be the bathroom light. After the bathroom light switch. So if you want light in the closet, the bathroom light needs to be on.  Since I live alone, not a big deal. But it's definitely on the long list of screwy wiring in my house that needs to be fixed.  Most recently, the bedroom switched receptacle stopped working so I need to pull that apart and see how much of a PITA that will be.  

Also, one of my favorite Steven Wright bits:

“In my house there's this light switch that doesn't do anything. Every so often I would flick it on and off just to check. Yesterday, I got a call from a woman in Madagascar. She said, 'Cut it out.'”