Why I Hate Electrical Work.

[Mudbone]

Electrical work should be straight forward, just like plumbing except with wires instead of pipes, right? Not always.

My garage lights are on a three way circuit. One switch is inside the house, next to the door from the garage to the kitchen. The other switch is on the other side of the garage in a totally useless location. I am finishing my garage so now is the time to move it. This three way circuit shares a breaker with another three way circuit, a four way circuit, four individually switched lights, and a switched bathroom fan.

So I shut off the breaker, disassemble the switch and box. This switch is at the end of the three way circuit so it has a single 14-3 wire running to it and nothing going out. I pull the wire back through all the studs to where it decends through the top plate. At this point I get distracted for about an hour or so. When I come back, I need to temporarily wire the switch back up so my garage lights will work. However, I realize I have forgotten which wire was the common wire for the three way switch. No Problem. I am a reasonably smart guy AND I own a multi-meter. I get it out, set it for 120V AC and turn the breaker back on. I start checking each of the wires back to the ground. Red wire, nothing. Black wire, 120Vs, there it is, that's the common. While I am at it check the white wire, 25 Vs WTF?

Anyone have a clue why I am getting 25Vs on that wire?

 

[Mr_fixit]

Oh, the mysterious phantom voltage. DO a search on phantom voltage.

 

[KinzeMech]

Likely, that line is floating. That is to say, it's not connected to a ground on the other end, be that through a device, or directly. Floating lines can take on an induced voltage from adjacent, parallel lines carrying AC.

Flip the remaining three way switch. I've got a dollar that says your red wire and your white wire will switch measurements.

 

[Gary S]

Digital meter?
Most digital meters have too high input impedance to be trusted where phantom voltages appear. They don't load the circuit enough to load down that phantom voltage.

 

[venturesomerite]

I had something simmilar happen a few years ago. Also was a three way switch for my hall lights. Turns out that the upstairs light box was being used as a junction box, and who ever put the lights in ran a 2 wire not 3 wire, so the stole a neutral from the other circuit.

 

[7th Kahuna]

Likely, that line is floating. That is to say, it's not connected to a ground on the other end, be that through a device, or directly. Floating lines can take on an induced voltage from adjacent, parallel lines carrying AC.

Flip the remaining three way switch. I've got a dollar that says your red wire and your white wire will switch measurements.

I'm no expert but assuming everything is wired properly then this would be a good place to start. Check to make sure the neutral (white) wire is properly connected at each junction all the way back to and including the panel. If it were already, then there would be no voltage difference across the neutral and ground.

Good luck

 

[Falcon67]

Electrical work should be straight forward, just like plumbing except with wires instead of pipes, right? Not always.

My garage lights are on a three way circuit...

I'm thinking about a 3 way toilet...

I think the others have it - a DVM will float on a traveler wire since nothing is happening on it. I would start at the breaker, find which switch it hits first with power and go from there on the colors.

 

[Alchymist]

I'm no expert but assuming everything is wired properly then this would be a good place to start. Check to make sure the neutral (white) wire is properly connected at each junction all the way back to and including the panel. If it were already, then there would be no voltage difference across the neutral and ground.

Good luck

That white wire at the 3 way is not a neutral - neutral is never switched. (Well, almost never. In an on/off switch for an appliance, sometimes both the hot and neutral are switched, special case).

 

[MileHigh]

Haha I feel you man. I just moved in to my new construction house last week. I payed for the ceiling fan pre-wire in all the bedrooms, but opted to install my own fans as the builder charges way too much and has too few options.

Last night I finally get around to installing my new ceiling fan/light combos. I wasn't planning on killing the breaker as, with the switches off I should have no power to the ceiling box. So I start on the first room and as usual I err on the side of caution and check the lines and to my surprise have a live one up in the ceiling. So I kill the breaker and install the fan/light. Turn the power back on and test the switches (there are 3 in each room). First one turn on the lamp plugged in the switched outlet, check. 2nd switch turns on the new ceiling light, check. 3rd switch does... nothing.

Long story short, after walking away and installing the other bedroom fans with no problems it hits me. I go plug another lamp in the bottom receptacle of the switched outlet and throw the 3rd switch, lamp comes on. They messed up and wired 1 switch to the top plug and one to the bottom plug

Now I could rewire behind the plate and fix this, but out of principle I'm going to make them do it. Plus they've painted over all the wires and I don't feel like scrapping them off to see what I'm doing.

Again, something that should have taken me 15min wasted over an hour and made me second guess myself. Oh well! Hope you figure it out!

 

[slickgt1]

I think the laws were way too friggen lax on these ******* builders back in the day. When I started renovating my house, I was planning on keeping the electrical as I wasn't really geared for that kind of work. In the end, it all got torn out. What a mess. I had junction boxes god knows where. I had power supplying my apartment going to the tenants. My basement light would turn on with my second floor bathroom light. Switches behind walls. You name it, I had it. I can do electrical work now, lol.

 

[Zeke]

This three way circuit shares a breaker with another three way circuit, a four way circuit, four individually switched lights, and a switched bathroom fan.

I guess that would be considered normal, but it tried to tie my brain in a knot.

 

[Falcon67]

Never done a 4 way, but have seen the video.

 

[richtersrodz]

Doah!!! ^^^ I had to run to HD and buy a book. I hated doing it, but actually needed it to figure out how to wire up the three way switch in my old kitchen.

 

[LutzTD]

I use my camara phone and take a picture of EVERYTHING before I take it apart, its not that I dont remember everything, im just too dumb to remember I cant remember everything.

 

[Mickey O]

Tip:

Mark your wires before pulling them out.

 

[marty_p]

I use my camara phone and take a picture of EVERYTHING before I take it apart, its not that I dont remember everything, im just too dumb to remember I cant remember everything.

You damn straight; I work smarter too!

 

[Alchymist]

Three way switch circuits are not rocket science. One switch is the feed side, the other is the load side, and there are 2 "travelers" between switches. 4 way is just a DPDT in the travelers between the two three way switches. Take a minute to draw it out using these rules and it becomes readily apparent how it works.

 

[Mickey O]

Now here's a tip that may actually be helpful when in this situation, I've done it myself many times, makes it real simple.

Disconnect all the wires, use your meter to identify the neutral & hot coming in, mark them for later. Now get a long piece of wire (we'll call it a test wire, I have a 200 foot or so piece of stranded wire I use for this), wire nut it to one of the wires (not the hot or neutral) at one of the switch boxes, now go to the other box bring the other end of the test wire with you and use the Ohm meter between the the test wire and the other wires in the box (that are not the hot or neutral) till you find the other end of the wire you connected to in the other box, mark it (with colored taper or wire markers), then go mark the other end with the same marker, repeat with the other wires. Then wire it up properly from scratch, goes real fast and you'll know it's done right and will operate properly.

 

[Mudbone]

Thanks for the replys guys.

Gary S, it's an analog meter. The old school Radio Shack one that they have had forever. (My dad has the same one, thirty years older.)

This thing is going to be a PITA to chase down. For starters everything is behind drywall. Even though my garge is not finished otherwise, the ceiling is insulated and drywalled because there is a room above it. Part of that will get removed for some new wiring but the problem is probably behind the walls in my house.

The second issue with chasing it down is that the two switches are on either side of the lights that they control. So there isn't a single wire running from one switch to the next.

And the biggie is all the other "sub" circuits that share that same breaker. The switch in my kitchen that controls the garage lights shares a box with a switch for one of the other three way circuits on that breaker. I have identified the 14-2 wire coming from the breaker, it goes to this box first. There are about 5-6 other wires, including these two switches, wire nutted to breaker wire. This box is crammed full. Presumably the other wires leaving the box are going to the other circuits on this breaker. SO, any current leakage from any of those circuits could be making its way back to that wire.

Long story short, I am hiring an electrician to help me upgrade my power from 200 amp to 400 amp. Guess what else he is going to help me do? Actually since I am upgrading my subpanel to a larger panel these lights may get pulled off onto their own circut anyway. But I stll need to chase that current leak down in the rest of the original circuit.

One other question. What is the proper definition of "circuit" I have heard it used interchangably with "everything that is on one breaker" and "everything that is on switch" IE a three way circuit or a four way circuit. By the first definition, this circuit has 12 switches controling 9 fixtures.

BTW, Falcon67, They do make three way toilets. They are called bidets.
And about that 4 way, I try to stay way from them myself. For some silly reason the first two chicks always think you are talking about including another guy.

 

[Alchymist]

Thanks for the replys guys.

The second issue with chasing it down is that the two switches are on either side of the lights that they control. So there isn't a single wire running from one switch to the next.

And the biggie is all the other "sub" circuits that share that same breaker. The switch in my kitchen that controls the garage lights shares a box with a switch for one of the other three way circuits on that breaker. I have identified the 14-2 wire coming from the breaker, it goes to this box first. There are about 5-6 other wires, including these two switches, wire nutted to breaker wire. This box is crammed full. Presumably the other wires leaving the box are going to the other circuits on this breaker. SO, any current leakage from any of those circuits could be making its way back to that wire.

First off, everything on that breaker is "one circuit". Nothing new in this. There should be no "leakage current" in any of the wires. Stray inductance/capacitive pickup, yes. Leakage, no).


Get 3 pictures up - one showing the wires in each 3 way switch box, and one showing the wires in the light - we can most likely figure it out from that.

 

[Zeke]

Never done a 4 way, but have seen the video.

No one caught that?

 

[Alchymist]

Never done a 4 way, but have seen the video.

No one caught that?

I "tried" to ignore it....

 

[JerseyJim]

Didn't see this post right away... But just had to add one of my experiences to the list. I have a brother-in-law who is reasonably handy when it comes to plumbing problems, but would burn the house down when it comes to electrical.

He bought a house years ago and called me up to tell me he had electrical problems and asked me to take a look. He lived a fair distance away. I told him not to touch anything and I would come check it out. When I got there, I found a four gang box pulled completely apart with all the switches removed and 17 wires hanging out the front. Of course my B.I.L. had decided not to wait and went ahead and started to FIX things.

Ended up having to trace everything. Of the four switches that HAD been in the box, there were three 3-ways. Hours of work as you might imagine. Once I finished tracing and marking everything, I asked him what just exactly was the problem in the first place. He said that none of the lights were working. I shined a flashlight through the KO's at the back of the box and saw a single conductor back there. Here the house had been wired with aluminum and the feed for the box had snapped off and pulled back into the wall. If he would have left things alone, I could have diagnosed the problem in minutes.

I sympathize with anyone battling a three way circuit. But let me tell you... three of them in one box is daunting challenge. Came close to killing my brother-in-law that day. With a jury of hands-on type guys, I never would have been convicted!

 

[KinzeMech]

I sympathize with anyone battling a three way circuit. But let me tell you... three of them in one box is daunting challenge. Came close to killing my brother-in-law that day. With a jury of hands-on type guys, I never would have been convicted!

If they're going to call it a jury of your peers, that's what it should be