Small wiring puzzle

[Aaron Fude]

I'm sure you guys will crack it instantly.

I'm replacing a light and the switch that controlled it. I removed the switch first. The switch connected a black and a white wire that came in the same sheath. The white one was hot. (I know that sometimes this means something, but what?)

Then when I removed the light I discovered that it, too, had a black and a white wire connected to it, and the black one is hot. Now that the light is disconnected, the black whire is still hot, but the wire that used to be connected to the switch is now dead.

There are no other wires in either electrical box.

I'm racking by brain, but can't figure out how everything was connected.

Many thanks in advance!

Aaron

[Speedy Jim]

As I see it: The switch was (improperly) wired into the Neutral side of the Line.

splice Neutral ___________0 sw 0_________X_________0 light 0_____Hot Bk Wh Wh Bk

It may not be possible to correct the mistake without opening walls, etc.

Jim

[metspitzer]

The two wires at the switch go on the two terminals on the switch. At the light, black to black and white to white.

You can put some tape on the white wire at the switch but it works fine without it.

[Nate Nagel]

If it's a switch leg, it ought to be able to be fixed without busting anything open.

nate

[John Grabowski]

I'm thinking that there is another junction box somewhere where these wires could be connected. Is there another light fixture in the same room? Is there an accessible attic above so you can go see if there is a junction box up there? Did an electrical box get buried during a remodel?

[Cliff Hartle]

Here is what you have.

The white wire in the switch box should have been marked with black tape or sharpie. You'll see that in the picture that the white wired is marked this way.

[metspitzer]

If you put the tester down and just look at what you have, you can't really go wrong.

[RBM]

I agree, the op either missed the second cable and splice in one of the junction boxes or there is obviously a third box, and they mistakenly broke the neutral through the switch>

[RBM]

I think he's just trying to figure how it works, not so much, how to put it back. As you said, he really can't go wrong. I belive he's thinking that with the switch wires disconnected, he shouldn't still have a hot wire at the light, which is correct, except for when the neutral was switched instead of the hot

>

[Aaron Fude]

.

Hi,

To clarify matters - yes, I'm just trying to figure out how it works, not how to put it back together. And I still don't get it.

There are *only* to wires in each electrical box. I'm sure I did not miss anything, because I have now removed the electrical boxes. Each of the two wires came from a single romex.

So Cliff's suggestion was mostly likely, but that is not it. So I am still puzzled.

One thing I am thinking is that I've been using a cheapo pen-like voltage detector. Maybe my readings are wrong. I will go back and use something a little bit more refined.

[Cliff Hartle]

Let me get this straight.

In the box for the switch there is a black and white wire and in the light's box there is also only a black and a white.

In my post I assumed that the cable in the switch box was also in the light box and should match the diagram.

If this is the case then there has to be another box somewhere between the switch and the light.

Also I believe that digital multimeters can give weird readings or you have some majorly screwed up wiring like things wired in series instead of parallel.

Good Luck

Hi,

To clarify matters - yes, I'm just trying to figure out how it works, not how to put it back together. And I still don't get it.

There are *only* to wires in each electrical box. I'm sure I did not miss anything, because I have now removed the electrical boxes. Each of the two wires came from a single romex.

So Cliff's suggestion was mostly likely, but that is not it. So I am still puzzled.

One thing I am thinking is that I've been using a cheapo pen-like voltage detector. Maybe my readings are wrong. I will go back and use something a little bit more refined.

[metspitzer]

Sounds like to me he is just trying to get a voltage reading across the switch.

If he took a switch out he would only have 2 wires to put back. You can't really mess it up.

When he took the light down, there is only 2 wires to put back too.

Seems like he is mistaken of the meter readings.

[Aaron Fude]

Metspitzer, I appreciate what you are saying, and that's what it should be, but that's just not what it is and I'd like to figure it out.

So here's additional information.

And the fixture:

1. The black wire is definitely hot.
2. The voltmeter shows zero voltage across the black and the white when diconnected at the switch.

"In between": With the circuit off, I performed a connectivity test by testing for resistance. When I touched the two wires at the fixture, the resistance went down to zero when measuring at the switch.

At the switch: I. Both wires dead when wires not touching at the fixture. II. With wires touching at the fixture, the white wire is hot and the voltage across the wires shows 120V.

Does that help shed light on the situation?

Thanks!

[metspitzer]

Use this drawing.

We make the top splice A Black wire at the light B White wire at the light C

Black wire at the switch D White wire at the switch E

The chepo pen actually would be best in this situation.

With the swtich on you should have power at A,B,D,E With the switch off you should have power at A,E

[terry]

...

Use a bulb not a tester. Even cheap testers can pick induced voltages on disconnected from adjacent working wires.

Sounds like two possibilities.

1) As some have pointed out the switch may be wired into the white (neutral) side of the line to to light. However more likely it may just a confusion of colours by whoever wired it previously. 2) In order to switch ceiling lights on and off, the two wires down to the switch could (are likely to) be: a) A live lead (s'posed to be black but may not be) from the supply. b) A wire that connects to other side of the switch. This lead although it may be white is called a 'Switched Live'. So that when the switch is ON there is voltage that wire goes to the light fixture. At the light fixture the neutral (white) side should be solid back to the supply (neutral) and the 'switched live, which may be white possibly marked with tape or nail polish in some way!**) provides switched voltage to the (live wire) of the light. Unlikely to be any neutral wires at all in the switch box. 'Usually' all neutrals up in the ceiling run to the light fixtures. Some jurisdictions suggest that switched live be red not white but usually accept some form of marking of a white wire as a 'switched live'. So one may see white/black from fuse panels to each ceiling fixture but red blacks down to each switch. Where blacks are live and the reds are switched lives!

[terry]

Remote possibility? Interesting how we tend to say "Three way switch" even though each switch has only two positions and there ae only two of them. However don't think this has anything to do with OPs wiring question?

[John Gilmer]

True.

BUT when you hae a "switch loop" (a switch with just one black and one white wire coming in) the white wire is almost always the one that's "HOT" all the time and the black is the one that is connected to the lighting fixture "hot" lead.

Most folks can quickly figure out that any and all of the wires going to a switch will be HOT at least some of the time.

** Posted from **

[RBM]

In that case, what John Grabowski suggested, must be correct. There is a third junction box. If disconnecting the two switch conductors does not kill the hot in the lighting outlet box, then it was the neutral that was broken through the switch

[RBM]

Exactly, and then you don't have to guess at which of the two white wires at the light, is the neutral

[John Grabowski]

Hi,

To clarify matters - yes, I'm just trying to figure out how it works, not how to put it back together. And I still don't get it.

There are *only* to wires in each electrical box. I'm sure I did not miss anything, because I have now removed the electrical boxes. Each of the two wires came from a single romex.

So Cliff's suggestion was mostly likely, but that is not it. So I am still puzzled.

One thing I am thinking is that I've been using a cheapo pen-like voltage detector. Maybe my readings are wrong. I will go back and use something a little bit more refined.

Use a pigtail socket and light bulb for testing.