More Electrical Puzzles: help!

Saw Drum God’s thread about wiring and found out there’s quite a number of electricians around here!

So on to the Q:
I have an outlet box with two sets of leads coming into it. One lead pair went to each of the plugs. The odd thing was that the pairs were crossed. IE, black from one went with white from the other.

On the wall there’s a switch which switches one of the plugs. The switch, as it turns out, connects two black wires. In the back of the switch box I find two white wires that have been connected.

When I uncrossed the wires at the plug, the first plug was STILL always on, but now the switch failed to activate the second.

I’m trying to replace the switch with a rheostat for a low voltage magnetic lighting system, but it does not seem to be working properly.

Is this enough information for someone to explain to me what is going on?

I sure hope so…

I may not understand exactly what’s going on, so this is merely a ‘don’t make it any worse’ post.

Recross the wires at the plug until they are back the way they started and everything works. One of the plugs is supposed to be on all the time. The other one is switched.
After it all works again, don’t replace the switch with a low-voltage rheostat unless that’s what the instructions say to do, and I would would want to read those again.

(I do electrical work during the day, why am I doing this for fun?) Good call about the split receptacle! If you take a look at it, the side with the neutral probably still has a small metal tab connecting the two terminals together, but your hot side probably has that tab broken out. If this is the case, you probably got very lucky that the two black wires were the same circuit or phase, because you would have applied 240V across your still hot receptacle.
Okay, now that I’ve thought about it some more, I can’t explain how you didn’t blow something up. See if your receptacle is how I’ve described and let me know, I’ll try to help you some more.

Folks, this is the way I found the stuff, I didn’t set it up this way. I’m trying to understand why it was set up like so before I go futzing with it.

I know I need the above-described rheostat because I am plugging in LVM halogen lights and that’s the only type of rheostat they work properly with (so say instructions, and so my experience with other home improvement projects bears out).

tcburnett, with the wires crossed, the one plug is always on and the second works via the switch. with the wires uncrossed, the one plug is still always on and the second one is always off, regardless of the switch.

To clarify, by crossed I mean Black from pair 1 and White from pair 2 are across one set of plug leads, etc.

I sure don’t get it.

Thanks for the input…

Is the LVM lighting going to be plugged into the receptacle that operates on the switch? Or is it going in the ceiling, wired with another box? Do you want to keep one of the outlets working (either switched or non-switched)?

As gapcity said, the small metal tab that connects the upper and lower outlets is probably broken out on the hot (black) side, so the outlets can be powered separately (but have the same neutral (white) connection). You can tap off the switched-outlet hot wire if you want switch-operated power, or the other hot wire if you want it on all the time.

You might want to think twice if you’re planning on putting some kind of dimmer on the outlet power (i.e. you’re going to plug in a light into the outlet, and want a dimmer on the switch). Some day somebody will unplug the light and plug something else into the outlet, that might not like being dimmed (such as a computer or other electronics). Other than that, you should be ok replacing the switch with your dimmer, as long as it’s designed for 120V systems. It probably requires you to have a neutral in the switch box also, which it sounds like you do (the two connected white wires).

Arjuna34

Arjuna34

Arjuna34, I don’t really care whether the outlet stays a useful outlet, I just need one reliable pair of leads in that box (where the outelt is/was) that are connected to the rheostat in the other box (where the switch was). S’okay with me if I dedicate it to the light.

Bump.

Based on the response. I’m beginning to suspect this is not a problem which can be diagnosed remotely.

Damn.

If you can draw it out and then scan that and link it you have a much better chance of diagnosis.

It seems like the wires were run to one outlet then to the switch and then back to the other outlet.
That would explain why there are two whites joined in the switch and why it operates on the blacks.
The wires leading to the switch would both be hot, one a permanent live from the first outlet, and the other a switched live to the other outlet.

What might be useful is to determine which wires are coming from the fuse box(incomers).Once you have done this you ought to be able to disconnect the other wires and trace them using a meter and,if you know what you are about, a diode.
If you want to discuss this further then e-mail me

Is it usual to have wall sockets switched remotely ?
All ours have the switch incorporated onto the body of the outlet.

“He puzzled and puzzled 'til his puzzler was sore.” Two Questions: There are four wires in the switch box-do they all go out one way or are there two sets of leads? I assume two sets, one to the outlet and one from parts unknown. Next: Same deal for the outlet box? two sets of leads, one from the switch and one from parts unknown. Soooo…either the juice comes from the unknown outlet leads or the unknown switch leads.
Sometimes when a less than savvy electrician installs greenfield or Romex, he will use a black/white/green combination going to a switch. If black is hot, white becomes a switched hot, a code no-no but I’ve seen it done.My only other guess about hot whites results from a ground fault on the black, in that case you can’t use it for a hot so an unsavvy electrician uses the white for a hot. In this case, things go boom if you swap your leads, so I don’t think this is your problem.
Your low voltage lighting rheostat-does that step your voltage down or is there a separate transformer elsewhere? What exactly went wrong with it?
It is worth the $15 or so to invest in a “tic” tracer, a penlight-looking thing available at most electrical supply houses that beeps or lights up whenever it approaches a hot wire. It can give you a good idea of where things might be awry. It’s also fun at parties.
I’ll return my verdict when you answer these questions!

Tell me about it…

I can’t tell. By the time they get into the box all four wires seem to be independent. I’d have to dig around behind in the wall to see and I’m trying to avoid that.

All I know is: I’ve got 2 W and 2 B wires.

FWIW, I did some testing on these wires. The two whites are twisted together. With the fuse on, I checked for current across the paired whites and a black wire (testing each black individually) and there was none.

I seriously doubt that whoever installed this use the colors as prescribed.

Ahh, the outlet box is easier. The black/white pairs come into the box inside casings. Each casing contains 1 black, 1 white and 1 ground.

As I said before, regardless of the switch, one B/W pair is hot. I guess I mean one black is always hot, if white is ground, right? But maybe it’s not safe to assume that…

There is a transformer to convert High voltage AC to low voltage DC. the DC goes to the lights. I wish to connect the transformer where the outlet now is.

The lights do not dim properly when a “regular” dimmer is used (the dimmer is on the AC side). Need a special dimmer.

I have confirmed this at a seperate installation that did not have weird wiring, where I put a similar transformer up and connected it to a special wall dimmer.

At the weird installation, when I connected the dimmer to the wires where the switch now is, it failed to function entirely. I think it blew, because it does not work elsewhere now either.

I suspect the odd black-black pair, hence this thread.

Sounds like I need to get some cheap current testing tools. Any other advice also welcome…
Hope that answers your Q. Thanks again for all the input…

Haha! Light bulb goes off!(on?)
Your measurements on the switch are helpful. Regardless of the color scheme, it appears you have a switched neutral.(Big code no-no!) You can verify this by checking your switched side of the outlet to ground with the switch in the off position. If you have juice on either the black or white, your neutral is switched. To be safe, I would wire your new stuff on the always hot side of the outlet. If you had conduit, like Chicago, you could pull new wires to your wall switch.(If we had ham, we could have ham and eggs if we had eggs.) otherwise, you just have to put new wiring to your outlet box and mount your dimmer in a convenient spot. Cap off the rest of that crap, remove the switch and connect the two blacks together too. Hope I’ve been of service!

Ren, my first advice is to call an electrician, and let him figure it out. You don’t want to be guessing with electricity. gapcity’s remark about you beiong lucky there wasn’t 240 volts in there is on the money. A professor (EE, no less) I knew from college set his printer on fire once. Each outlet pair in the room had the top outlet on one leg, and the other outlet on the other leg. He didn’t know this, and put 240 through his printer when he wired it up differently.

If you ignore my advice above, then at least find out exactly what you have going on. It sounds like you may have a circuit (black/white/ground) going directly to the outlet, and another circuit going through the switch, and on to the outlet, which is not code. When you pull the fuse or switch off breaker to the outlet, have you checked all the wires at the switch, to see if they have power? If so, you have two different circuits. If not, you may still have two circuits both wired into the same fuse.

Also, when you check for power, do you know what voltage you’re getting? If you just have a neon tester, it would still glow at 240. I don’t think it would necessarily burn out.

With the fuse on, but the wires at the outlet disconnected and not touching one another or anything else, the switch off, and the white wires at the switch disconnected, is there power at the switch between a black and white pair? If so, this is the second source of power. (OK, you’ve already done this, and got no power, so skip to the next paragraph.) The other black/white pair of wires probably go to the outlet. With the power off again use a continuity tester to verify that white at the switch is connected to white at the outlet, and the same for black. If more than one pair of black and white have power between them, give up and call an electrician. It’s too messed up.

If none of the pairs have power, some of the wires may just be floating. In testing the wires at the switch, it would also be good to have a known good ground. When you’re testing for power at the switch, if one wire (or two) is at 120 volts, and the others are not connected to anything, you’d never register power. Likewise, when you think you have the wires which go from the outlet to the switch figured out, it would be good to check for voltage or continuity between them and ground.

If you can determine that one black/white pair at the switch goes to the outlet, you can wire up your switch to code*. Continuing with the fuse off, snip off the exposed leads of the black/white pair at the switch which doesn’t go to the outlet, and wrap each separately with electrical tape. You won’t need them. (Actually, you should do the snipping at the end, if everything is working OK.) Connect the black and white wires that go to the outlet to the switch.

Back at the outlet, the black and white coming in with power can be connected up to the unswitched outlet. The White side needs to be connected to the white side of the other outlet, if the tab on the outlet is broken off. You need to connect the black wire to one of the wires which go towards the switch. The other wire from the switch goes to the black screw on the switched outlet.

Remember to observe the correct polarity. Also, make sure that black to ground on the incoming power forms a circuit, and not white to ground. If this is switched, your black and white wires are reversed.

With the switch off, put the fuse back in. The unswitched outlet should work, and the other should be off. Turning on the switch should turn on the switched outlet. I’d cross my fingers here, which is why I’m going to repeat that bringing in an electriciian is a better idea than doing it yourself, even if you’re talking with an electrician on the SDMB (referring to gapcity. I’m not an electrician.).

(*) gapcity seems to contradict this. gapcity, I thought that a black/white pair could be used to run from a light or outlet to the switch controlling it, and back.

Hey, folks, thanks for getting back to me. I was just planning to get back to work on this conundrum today, so the replies are timely! gapcity, I thikn you’re correct, the switch is on the neutral side of the circuit. Yuck.