Open Neutral question

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Old 02-04-08, 07:12 AM
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Open Neutral question

I have a ceiling light fixture as part of a three-way switch. It runs fixture-switch-switch. The ceiling fixture has an open neutral, which I can't locate where it sources from, as I've checked the other outlets on this circuit. My concern is that it could be in the wall - the previous owners must have hung a very heavy picture right above one of the switches, becuase there is a huge plastic anchor in the wall 18 inches above it - could they have punctured the wire and severed the neutral? I really don't want to open up the wall on a hunch.

As an alternative - it's old BX line with the metal sheath - can I use this at the fixture as my neutral (i.e., use the grounding capability as my return?). I know it's possible, and will complete the circuit, but worried about creating a fire hazard with this old house.
 
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Old 02-04-08, 08:59 AM
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If the wire is causing the open it must be replaced. I would trace the wire back to the previous connection box and make sure a bad connection is not causing the open. If you are not comfortable doing that call an electrician.
 
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Old 02-04-08, 07:19 PM
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I've checked each outlet on this ciurcuit, which are all between the light and panel. None show an open ground. What are my next options/areas to check? Can I use the ground at the light as the neutral?
 
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Old 02-04-08, 09:36 PM
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First of all, you absolutely, positively cannot use your ground as a neutral.

Second, are you confusing open neutral with open ground? You say you checked every box for an open ground, but your problem is an open neutral.

99.9% of all open neutrals are in a box somewhere, often due to a failed backstab connection and sometimes due to a poorly applied wire nut.
 
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Old 02-07-08, 09:36 PM
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Ok, I checked all the receptacles and switches on this circuit, and everything is fine. No open neutrals anywhere but at the fixture. This is getting frustrating, not sure what to do next. Maybe if I explained the three-way switch, this may help. Be warned, this is long.....

I am assuming the 3-way goes fixture-switch-switch, as there are only two 2-line cables going to the fixture. The hot wires are connected to each other, while the whites from each cable go to the light. Am I correct in my assumption the power comes here first before going to the switches?

I'm having trouble telling which switch is next. I figured that the first switch should always have 2 possible "hot" wires whether the switch is on or off - the common and one of the travelers. But the 2nd switch should have either one or two "hot", depending upon if the switch is on or off. (I'm testing "hot" vs. "cold" wires by using a standard voltage tester and always touching one prong to the metal box as my ground). Oddly, neither switch has the situation where two wires are always hot.

To further compound the issue, at one switch an additional wire is attached to one of the terminals, and at the other switch, two additional wires are attached to separate terminals. All are in multi-gang boxes and part of separate cables coming in to the box. I could understand if one additional wire is attached to the common terminal of the first switch, in essence "stealing" power to go somewhere else. But I'm thouroughly confused how the 2nd switch in this series could have other lines attached - won't these be part of the three-way switch?

Am I totally incorrect in my assumptions and could that be causing the problem at the fixture? I'm usually pretty damn good at this stuff (have wired lots of stuff before, run new lines, put in new fixtures/outlets, etc, including 3-way switches), and I hate to admit defeat.
 
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Old 02-08-08, 06:44 AM
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A switch loop wired as power- light-sw-sw will have one 2 wire cable and one 3 wire cable in the first switch. Only one wire in the 2 wire cable will be hot to ground when all the wires are disconnected. The second switch will only have one 3 wire cable. If you have any more cable than this then you don't have power- light -sw sw or someone has done someting that won't work.
Please describe all the wiring in all the switches.
 
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Old 02-09-08, 09:14 AM
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I took the switches out to test the wires. Each of the switch's three wires has one hot/two cold (to ground). Each shows a completed circuit when touching one of the hot to one of the cold.

However, each switch sits in a box with another, separate three-way switch controlling a separate light. Each of the "problem' switches has one wire connected to one of the terminals of the 2nd, operational, three-way switch. How and why would these two seemingly independent switches be connected? And how could both of the "problem" switches have power?
 
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Old 02-09-08, 11:48 AM
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They can't. They are wired wrong. If power comes into the fixture like you stated in your first post then there should be no connection to the other switches. If power comes into one of the switch box instead of the fixture then only one of the switches should have a connection to the other switch. That connection should be the always hot power connection from the breaker.
 
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Old 02-09-08, 12:37 PM
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Ok, so I finally tested my original assumption of power going to the fixture first by disconnecting what I thought were the two hots, and now that I've disconnected all switches, there is no power at the fixture. There is still one hot wire at each switch.

So with this knowledge, how does this three-way work? My basic understanding of three-way switches assumed one of three scenarios:
1) Power->fixture->switch->switch - should only be two 2-wire cables going to fixture, with both "hots" connected from each cable, and the two other wires connected to the fixture. This is the setup I have in terms of wiring, but obviously no power is coming here first.
2) Power->switch->switch->fixture - should only be one 2-wire cable going to the fixture.
3) Power->switch->fixture->switch - should have two 3-wire cables going to the fixture, travelers wired together at fixture, with common and return attached to the fixture.

Given I have wiring setup #1, with no power at the fixture, and power at a wire at both switches (with switches removed), AND with sharing of wires between separate switches controlling separate three-way lights at each box.....what in the hell is going on here????

Next step, which I don't want to do yet, is to pull out the other 2 switches and identify all wires (how many cables, how many 2-wire vs. 3-wire, etc.), but it's a spagehtti factory in there, and I'd like to try and figure as much out first before I take apart the other three-way switch system that is working.

I guess this was set up with some "short-cuts" in terms of multiple-wire cables for both 3-way loops, but I can't figure it out. Is there a standard practice of sharing wires between 2 separate 3-way switch loops when they are in the same box?
 
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Old 02-09-08, 05:43 PM
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You have two completely separate circuits that are either #2 or #3 of you list of setups.
The power wire goes to the common on one of the switches. The switch that has the power on the common goes with the switch that does NOT have the power at the other end.
Give us a complete inventory of all the cable and wires at each switch and light fixture. We should be able to figure this out.
We don't need the grounds. They all get connected together everywhere.
 
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Old 02-10-08, 01:26 PM
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At each fixture, there are 2 2-wire cables coming in, one wire from each connected to each other, the remaining two wires connected to the fixture.

Upstairs and downstairs - two three-way switches in one box controlling 2 separate lights. All cables are 2-wire - there are NO 3-wire cables at all.

Downstairs - 4 2-wire cables coming in to the box. Cables 1, 2, & 3 - one wire from each cable are pigtailed together, then goes to one terminal on each switch. The other wire from these 3 cables are also pigtailed together, and then go to another terminal on each switch. The remaining cable #4 has one wire to the third terminal of switch one, and the second wire goes to the third terminal of switch two.

Upstairs - similar as downstairs, although there are only 3 2-wire cables coming in. Cables 1 & 2 - one wire from each cable are pigtailed together, then goes to one terminal on each switch. The other wire from these 2 cables are also pigtailed together, and then go to another terminal on each switch. The remaining cable #3 has one wire to the third terminal of switch one, and the second wire goes to the third terminal of switch two.

In both upstairs and downstairs, when touching both sets of pigtailed wires to the prongs of a tester, I see power. Touching the hot pigtail set to either of the two "independent" wires shows nothing.

I'm not familiar with this type of 3-way switch. Would love to understand this....and also curious as to why the downstairs fixture shows the open neutral.
 
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Old 02-10-08, 04:09 PM
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You have totaly confused me on this one. Fixture wiring sounds like a switch loop with power at fixture. Yet your test show power at switches.
This some testing done to determine which cable go where.
I would start by making a detatiled note of how it is connected now. Then disconnect everytihng and find which black and white wires have the power.
Then the unpowered cables need to be traced to see which ones go between the switches and which ones go to the light fixtures.
 
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Old 02-10-08, 05:13 PM
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Everything is tagged and disconnected. I drew a map - how can I attach? #'s represent the cables, letters represent the terminals at the switches (A/B/C for switch 1, D/E/F for switch 2). S1 refers to the switch that controls fixture 1 - same for S2.

Downstairs - Hot wire comes from cable 1, 2, or 3 - all are pigtailed then go to terminal B and F. Testing B/F to a ground (metal box) shows curent. Testing B/F to A/D shows current. No reading is obtained when I test B/F to either C or E. So it appears B/F is the hot, A/D is the neutral. C and E could be travelers to the fixture (maybe - no idea).

Upstairs - Hot wire comes from cable 1 or 2 - all are pigtailed then go to terminal C and D. Testing C/D to a ground (metal box) shows curent. Testing C/D to A/F shows current. No reading is obtained when I test C/D to either B or E. So it appears C/D is the hot, A/F is the neutral. B and E could be travelers to the fixture (maybe - no idea).

I could undo the pigtails on the hot to determine which cable is the source, not sure if I need to. How can I test which unpowered cables go between the other switch and the fixture?
 
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Old 02-10-08, 05:16 PM
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Sorry - left something out (easier to see with map):

Downstairs - non-hot wires from cables 1,2, and 3 are pigtailed and go to terminals A & D.

Upstairs - non-hot wires from cables 1 and 2 are pigtailed and go to terminals A & F.
 
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Old 02-10-08, 05:52 PM
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To attach a picture you need to host at some place like photobucket.com and then link it.
You also need to disconnect everything and determine for sure which wire is the hot. You also need to determine where the cables go. For example does cable A go to light or other switch box? While you have everything disconnected determine if anything else on the circuit is not working.
 
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Old 02-10-08, 06:41 PM
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Ok - see link for Photobucket:

http://s250.photobucket.com/albums/g...-wayswitch.jpg

Disconnecting pigtails now and will test remaining circuit.

How do I determine where the cables go?
 
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Old 02-10-08, 07:10 PM
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Don't label the terminals ABC. Find the COMMON terminal and label that one. The other two don't need lables. They are travelers. Identify the whites and blacks also.
 
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Old 02-10-08, 08:12 PM
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Did you download the picture?

How do I identify the common terminal - can I assume the one different-colored screw is the common? If so, C&E from downstairs and B&E from upstairs are common terminals. However - this is an old house, with Bx metal-sheathed cable with cloth-covered wires, and old switches. I don't necessarily trust that the original electrician used the different colored screw as the common.

Downstairs - Black wires are all pigtailed together that go to B&F. Whites are all pigtailed together that go to A&D. For cable 4, black wire is C and white is E.

Upstairs - Black wires are all pigtailed together that go to C&D. Whites are all pigtailed together that go to A&F. For cable 3, black wire is B and white is E.

Hot comes in from cable #1 in the downstairs box - disconnecting this pigtail now stops power from going to any other outlet/light on this circuit - including the upstairs set of switches.

How can I now test where the other cables/wires go? Do I do this by connecting pairs of black wires (that were previously pigtailed) one at a time?
 
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Old 02-10-08, 09:02 PM
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I answered my last question by pairing the blacks in the downstairs box together 2 at a time. Cable 2 feeds the upstairs switch (among other things). The upstairs switch power is not dependent upon the downstairs switch.

I have a theory - each switch has one hot, one neutral, and ONE traveler. Both upstairs and downstairs, the traveler is attached to the common terminal. Loop goes switch-fixture-switch.

If downstairs common is switched to neutral (meaning switch is flipped and common connects with neutral), and same thing upstairs, the light is off, as neither switch is delivering power to the fixture.

If downstairs common is switched to hot, and upstairs common is switched to neutral, then the light turns on. Power goes through downstairs hot, through switch to downstairs common, through downstairs cable 4 to light, then returns through upstairs cable 3 to common, which is switched to nuetral, thus completing the circuit.

If downstairs common is switched to neutral, and upstairs common is switched to hot, the light is also on, as the whole thing reverses - power goes through upstairs hot to common (through switch), through upstairs cable 3 to light, back through downstairs cable 4 to common, which is switched to neutral - again completing the circuit.

However, if both upstairs AND downstairs have common switched to hot, light is off, as there is no neutral for the power to return. But this means there is still power at the light, even though it is off. I'm very worried about what danger this could cause, as in essence, the light is getting 220 volts of power, with nowhere for it to return!

Admittedly, this is an amateur theory, but the best I can come up with. Thoughts? Has anyone encountered this before? I take it this is the creativity of old-school electrical work when 3-wire cable wasn't at hand (or when they were lazy).
 
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Old 02-10-08, 09:22 PM
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It sounds to me like something the "OLD TIMERS" would call a "California 3 way" .

the hots cancel each other to turn off the light.

It is neither safe or legal in this configuration, and may become too involved very quickly. If you arent comfortable with any of this , have a pro sort it out.

you are absolutely correct....The fixture can still be live , even with the light off.
 
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Old 02-10-08, 10:11 PM
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I did look at the Photo the OP proivided and it is a californa 3 way [ there are other name for this as well but it the same way ] and it is illegal to use this kind of connection it was banned way back 1920's [ not sure excat year they banned but they carried that pratice into late as 50's and still in use but not safe anyway ]

as long both hot lead are on the same phase [ leg] the lamp will read 0 volts even thru it is hot that why it dont short it out but put in the light bulb and one side of shell will be hot and centre concat will be netural until someone change the switch postion then it will reversed like shell is netural then centre concat is hot.

[ this is common curpit espcally after upgrading the service when the owner mention light bulb exploded because it change the leg postion and when you get right spot you will end up 240 volts KABOOM there go the light bulb unless you get smart put in 240 volt bulb ]

and that useally result is rewire it to proper legal 3 way connection.

the californa 3 way is very tricky to trobleshooting and not all electricians are faimaur with this set up.

Merci, Marc
 
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Old 02-11-08, 06:09 AM
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Wow...now what the hell do I do? Now that I've identified it, is it illegal to put it back together the way it was? If not, I'll be forced to rip the wires out of the walls - walls that are freshly painted. Any suggestions?
 
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Old 02-11-08, 06:58 AM
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Sounds like a carter or california three way. It also looks like the upper cable 4 and lower cable 3 go to the fixtures.
I think they also splat and each cable feeds each fixture.
How many cables are in the fixture boxes? It is beginning to look like the problem might be one of the switches is bad.
If we can figure out which cable go to which fixture I can probably draw this up.
 
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Old 02-11-08, 12:13 PM
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If not, I'll be forced to rip the wires out of the walls - walls that are freshly painted. Any suggestions?
Not necessarily. As I said earlier , It can get very complicated , but it is do-able. You have to make the call as to whether or not your comfortable doing it.

As Joed said, we need to know what cables are where and what they do, which ones are actually live , and which ones are "Crossfed" from a different location. No promises, but it may be possible to correct this with what you have.

Side note.... I didnt realize it at first, but as Marc(French277) said, The 220 situation would only occur with breakers on different legs. DONT REPOSITION ANY BREAKERS UNTIL THIS IS FIXED......There likely may be more of theses circuits in the house.....
 
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Old 02-11-08, 10:13 PM
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Ok, first the good news. I disconnected ALL wires at each switch and fixture location. And wouldn't you know - the last two wires, which happened to be at the 2nd fixture, had one wire which was loose and broke off in my hand??? This explains the original open neutral at the 1st light, as this acted as the return in this California three-way setup. Now this finally makes sense. I pulled the box out of the ceiling, made a fresh connection, and put it back up.

I re-attached a cleaner diagram of all connections - http://s250.photobucket.com/albums/g...witch_0001.jpg

There are no 3-wire cables - all are 2 wire.

From downstairs, cable 1 is the source. It feeds cable 2 which goes upstairs to the set of other switches, as well as feeding a few other outlets. Cable 3 feeds other outlets downstairs, so we can ignore. Cable 4 feeds the fixtures. Both switches have one terminal attached to the hot and one to the neutral from the source cable 1, and the common terminals are attached to wires in cable 4, which goes to the first fixture.

At each fixture, there are two 2-wire cables. At the first fixture, the whites (from different cables) are attached to the fixture, and the blacks are connected to each other. At fixture 2, the whites are connected to each other, and the blacks both go to the fixture.

The white and black from fixture 2 then feed to cable 3 in the upstairs box. In this box, cable 2 is fed from downstairs cable 2, so it carries a hot and neutral. Upstairs cable 1 feeds other outlets, so we can ignore. Like downstairs, the upstairs switches have one terminal attached to the hot and one terminal attached to the neutral both from cable 2, and the common for each is attached to the wires from cable 3.

I tested eveything one connection at a time - this is definitely the way it is wired.

Is there a way to re-wire this without the California 3-way setup? I realize now I can't get 220 there, as it's on one circuit breaker. But what is the danger if I use the old setup? Can I be electrocuted by touching the fixture or bulb? I can't see any other way to get this to work.
 
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Old 02-12-08, 12:48 AM
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the issues here are these.....

Electrical code specifies that the center contact be hot, and the "Shell' neutral, on a light fixture.

2) Only hot wires are permitted to be switched,(Switch controlled) not neutrals

Yes there is a "SHOCK HAZARD" from replacing a bulb.
with the lamp off..the both contacts are live. Unintentionally touching the fixture or its mounting, could close a path to ground thru your body.

You have 3 options,...Either correctly rewire it, remove it and abandon the wiring, or get it to work again and forget it...

Problem with the last two..abandoning it may eliminate a code required light source, depending on the room and its layout. Repairing the existing......Is a decision you need to make, taking into consideration the shock hazard and legality of such a configuration. unless your house was built in the very early 1900's, A grandfather clause for such ,I would think would be a fat chance.

I will completely admit, I am horrible at trying to "Think-OUT" a wiring diagram.I'm pretty much useless unless it is in front of me...So I wont spin you in circles by trying some lame concoction. Im sure one of the pro's will make sense of this, and tell you how to proceed. I could be wrong, but i dont see anyway to do this without running at least one new 3 wire cable.
 
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Old 02-12-08, 08:20 AM
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Here is a picture of what you have. I can't see any way to fix this without new cables between the switches. Upstairs is on the left.
The power comes in on the left. I have not included the cables 1&3 in the upper box that go to other receptacles. If you put it all back together it should work.


 
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Old 02-12-08, 11:05 AM
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Ok, I think I'll just put it back together as it was, and be mindful when changing the bulb. I'll know which switch combination will be the "double-hot", so I can at least use this knowledge to be safe. Of course, I could always turn off the breaker when changing the bulb. Is there any chance the entire fixture will be energized even if I ground it, or only the shell and neutral? If the latter, this further reduces the chance of getting zapped.

This was quite the brain-tickler - thanks to everyone for helping me figure this one out. I certainly couldn't have done it otherwise.
 
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Old 02-12-08, 11:09 AM
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The chances of getting shocked when changing the bulb are slim.
The switches would need to be in the hot-hot positon. You would need to touch the metal shell of the bulb AND a grounded object at the same time. Plus you don't change the bulb that often.
 
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Old 02-12-08, 12:51 PM
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I know it is a headache try to sort it out but down the road when you do the remodeling it will be good time to replace that set of wire and redo it to work properly and safer.

Merci, Marc
 
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