Help with old house switch box wiring

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  #1  
Old 11-27-05, 10:52 AM
pbillante
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Question Help with old house switch box wiring

I need some help troubleshooting an old switch box's wiring setup. The house was built in the 20s/30s and I don't know how old this wiring is, but my guess is its original.

I moved a line in my basement for the power to my dining room light. This involved removing part of the old BX cable that connected to the breaker box and replacing with Romex. The dining room light works fine, but now my entry light switches/lights don't work. I assume this is because the power supplies those lights also (I didn't know that at first).

When I opened the entry lights switch box cover to see if I could troubleshoot it, I found an old wiring setup that I couldn't understand how it worked. Here's a diagram I made of the connections:

<P><img src="http://us.a1.yahoofs.com/users/41c650e3z281e2ac0/54d8/__sr_/e847re2.jpg?phYYgiDBFObGkfVc" /><p>

<P><a href="http://pg.photos.yahoo.com/ph/pbillante/detail?.dir=54d8&.dnm=e847re2.jpg&.src=ph">Link to diagram</a><p>

All four of the lines entering the box are old BX cables. The switches are newer and I tested to make sure they are o.k. Two of the BX cables have three wires, the other two have two wires.

I was able to verify using a tester that the rightmost cable coming into the box is a hot lead, but for some reason the other two wires in that cable are not connected to anything.

Can anyone give me an idea where to start to troubleshoot this? Does this wiring make sense?

I already tried:
* Checking the switches (they are o.k.)
* Reversing the polarity on the new line I put in. (no difference)

Thanks!
 
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  #2  
Old 11-27-05, 11:03 AM
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Can you show us a BEFORE and AFTER drawing, of what you moved from where?, by chance? I like looking at pictures, anyway. Breaks up the monotony.

I follow where the line side to switch 2 is coming from and also is feeding switch one. That is your hot side, for both switches, power has to go through each of these switches and come out of the screw directly above the hot screw on the bottom of each switch., then go to a light, then return and connect up to a neutral wire. I just showed you how to get power to the light or lights, but you don't identify neutral wires. Only a ground wire (and you can't use that). We have to identify some of those other wires that are not hot at 110, and can determine are neutral.

2 and 3 are wired incorrect. You can't have just one wire and another wire, with that other wire going to ground. Neither 2 or 3 shows a neutral wire.

If you have a two-wire, and not a three-wire (three-wire has hot + neutral + ground, where two-wire only has hot + neutral), wired house, you have incorrectly taken neutral wires and wired them to the ground screw of the light switch. For two-wire systems, you wold have no wires attached to the ground screw of the switch, and that appears what you have incorrectly done.

I have to go to work now on doing an apt. make-ready and cancome back later maybe. Soemone else can jump in here and help you. Many smart electricians here.

This thread is fun, as with the picure, this maze you created can be unraveled and correctly put back together.

------------------------------------------------

Drivers licensed
 

Last edited by ecman1; 11-27-05 at 11:22 AM.
  #3  
Old 11-27-05, 11:42 AM
pbillante
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Thanks ecman, but I guess I should have explained better. The wiring diagram/picture shown of the switch box is what I found when I opened it up. I actually didn't do that wiring. I think it was done by the original electrician, and now I'm trying to figure out what he did. So, essentially this is still the BEFORE wiring as far as this box goes.

(Also, the wires shown in the diagram are all cloth-wrapped wires in BX cables and I can't tell what is what for most of them.)

The change that I made wasn't in this switchbox at all, but was in the basement. I just changed out a section of BX cable that was connected to the breaker box with a new section of Romex cable.

The problem is that now after my change in the basement cable, the lights in this switchbox diagram that previously worked fine, don't work anymore. Hmm...

Thanks!
 
  #4  
Old 11-27-05, 12:02 PM
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Originally Posted by pbillante
I assume this is because the power supplies those lights also (I didn't know that at first).
Shame on you. You should know what each and every breaker controls and what breaker controls each and every light, receptacle and appliance. This information could save your life and, of course, helps you avoid mistakes like this.

Originally Posted by pbillante
I just changed out a section of BX cable that was connected to the breaker box with a new section of Romex cable.
Obviously you did more than this (perhaps without realizing it), or you didn't get the connections the same when you were done.


The wiring in the switch box is certainly confusing, and would be wrong by today's code.

To help us figure out the situation, completely describe the wiring at each of the lights. by completely, I mean describe each and every connection.

Also, describe exactly how you replaced a section of BX in your basement. You said one end is in your panel. Where is the other end of the cable? What and how is it connected to?
 
  #5  
Old 11-27-05, 03:16 PM
pbillante
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Hi racraft,

You asked if I could describe each and every connection to the lights. I have not disassembled all of them (yet) -- as they used to all be working fine.

For the entry way lights (in the diagram), the exterior light is connected via a two conductor wire. The interior entry light, I have not disassembled, so I don't know.

The dining room light is a chandelier, it is working fine. I would rather not take it down unless I really must. It is also on a single-throw switch.

As far as the old BX cable I replaced in the basement -- one end was terminated at the panel. The other was terminated in a metal junction box nailed to a joist in the basement. I only replaced the section of cable between the panel and this junction box. On the other side of the junction box was a BX cable that went up the wall toward the switch to the dining room light. I did not do anything to that cable.

Is there a series of steps I could use to check the wires at the switch box?

I still have the old BX cable that I removed. I'm going to try hooking that back up just to see if I can get it to work at all.
 
  #6  
Old 11-27-05, 03:31 PM
pbillante
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o.k. -- here's an update. I've been able to get the entry lights to work again, but I still can't explain why. All I did was screw the switches back into the box (I was giving up) and reset the breaker. Apparently, the connection between the switch ground and the box is required.

(I had previously pulled the switches slightly out of the box to have a look at the wiring - hence the diagram above.)

Any idea why this wiring diagram works? I don't know what any of the incoming wires to this box is connected to. And, it doesn't give me a good feeling that this "works" and has been working like this for years...
 
  #7  
Old 11-27-05, 03:42 PM
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Undo the bottom screw at switch 2 for testing.

Test the wire that is leading to that screw that comes FROM #4 inlet-outlet at the top right of switchbox. I want to see if that is the incoming hot feed for sure, for starters. And the ONLY hot feed.

Do you have an outlet in the vicinity of this switchbox or copper plumbing or a radiator? Do this: Take an analog volt meter set to 250 volts setting and touch one probe to that wire I had you disconnect. Then touch the other probe end into an outlet nearby (ground prong if you have one would be prefered), or a radiator (this makes a good ground), or a plumbing pipe. If your volt meter does not reach, you can use a piece of romex or a whole extension cord to use as an extender of the voltmeter to be able to get to a known neutral wire or ground (I have all my extension cords marked on each end so that when I do jumper testing I know I have the same continous wire at each end. But for polarized extension cords, you can simply use as the big prong on one end, and the big slot on the other end of the extension cord.) I want you to be positive that the other end of the probe is to a neutral or ground, while testing that disconnected wire.

IF that wire is indeed an incoming hot feed - do not hook it back up yet. Touch your voltmeter probe, still set on 250 volts setting, to every other terminal that is in that switchbox to make sure there is not 2 separate hot feeds coming into that box, with the other probve still of course on your greoud or neutral somewhere. (I am trying to unravel a couple mystery wires in box 2 and 3 and the extra wire you have in box 4.)

......................................

I just got back from that condo and touch up painted almost the entire place in this time, plus hung some blinds. This is my first stop here, back at the board here.
 

Last edited by ecman1; 11-27-05 at 03:52 PM.
  #8  
Old 11-27-05, 04:01 PM
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Per your lastest update post:

Obviously if it works, you have no short - so, it works. Be happy.

But don't go doing all this fiddling stuff without knowing what you are getting into. For example - it is posible, unlikely, but possible, that not just 2 separate hot wires are in that box, but possibly from 2 different circuits. By playing switcharoo with unidentified wires, you could potentially create a 220 volt situation. Like I said, this is unlikely, but in wiring I have seen some pretty goofy stuff, and I always like to know exactly what I am dealing with before blindly undoing this, and hooking up that.

I know a licensed elctrician who when rewiring a duplex apartment house with wires he didn't fully identify, he created 220 in downstairs outlets and fried this guys amp, tv, and other things!
 
  #9  
Old 11-27-05, 04:04 PM
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Are these normal toggle switches, or is there something special about them?

I suspect some creative wiring that should at the very least be identified. The only way to do that is to examine the wiring at the the two lights that these switches control.

I also suspect, but am not convinced of, a ground being used as a return. If this is the case then you have a very serious problem that needs to be addressed.
 
  #10  
Old 11-27-05, 04:16 PM
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Originally Posted by pbillante
o.k. -- here's an update. I've been able to get the entry lights to work again, but I still can't explain why. All I did was screw the switches back into the box (I was giving up) and reset the breaker. Apparently, the connection between the switch ground and the box is required.

(I had previously pulled the switches slightly out of the box to have a look at the wiring - hence the diagram above.)

Any idea why this wiring diagram works? I don't know what any of the incoming wires to this box is connected to. And, it doesn't give me a good feeling that this "works" and has been working like this for years...
Your first paragraph: Not a code situation! That means that the switchbox has turned into a live neutral and not just a ground. Tht means under the right situation, you could get partially (most likely not fully, but partially shocked when you touch the switch/box.) I have never heard of such a situation before - having to make contact between the switchbox and switch to make the circuit go. Is the metal box got bx cable or conduit at the inlet-outlets at the top? I presume so, and that is how the return circuit is being completed. But this is not kosher.

Now comes the million dollar question of how to rectify this, to continue the neutral by another avenue. I'm goona look at that drawing again. But I know this right now: if nothing else, you should unhook the neutral wires off of switch #1's ground screw on the far left and nut those wires together. Because we already know that the bx is acting as a neutral-ground, that means your switches are being grounded when you tighten them in the box. So, to rectify this, you may have to run a separate neutral wire, wired with those other wires that I said to wire nut together, and run the wire down the wall, through the floor, into the basement and to the panel box neutral bar to complete the missing neutral -if it indeed is missing, which seems awfully strange.

But of all those wires in that switchbox, I can't hardly believe that there isn't a neutral wire there that is independent of the bx armor to make it's way back to neutral in the panel box. You will have to analyze this as to why on earth that could possibly be.
 
  #11  
Old 11-27-05, 04:25 PM
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In the #4 inlet-outlet hole at top right of switchbox - what are the two wires to the farthest right that you have black dots on the bottom of? What is with them? I have pretty much figured out that there are no other wires to the left of those wires that can be a neutral. So I have my eyes on those 2 unidentified wires. Please respond.
 
  #12  
Old 11-27-05, 05:53 PM
pbillante
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The two unidentified wires coming in from cable #4 are just capped -- not connected to anything at all. I thought that was quite bizzare given that the hot lead came in on the same cable. I put a wirenut on top of each and wrapped it in electrical tape before I closed the box.

I would have to guess that one of these two is a neutral that returns. But, how can I verify?

(Also there's not much slack with these wires in the box -- maybe 3" on each -- so I've been avoiding disconnecting and reconnecting.
 
  #13  
Old 11-28-05, 06:11 AM
dcohalla
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old house switch box wiring

I too have an "older" house, with copious peculiar wiring. You know the kind, inline splices, inline switch tie-ins, no junction boxes. Just finished re-wiring my kitchen and dining room last Saturday. Had to replace all the runs and remove all the old...
I have found it helpful to do the following:

1. turn off breaker/remove fuse for that circuit
2. Pull the light fixtures down so that you can see the wiring
3. Do some basic continuity checking (hence the power being off)

and/or

go up in the attic, if possible, and observe how the wiring is run. (warning: you might want to "buck up" before you do up in attic...what was once acceptable wiring practices will create some serious rectal puckering for most folks... )


Find out how the fixtures are wired and what wire goes to which switch and it helps complete the understanding for what is what. I noted from your diagram that we only have 1/2 the picture. I have found some VERY interesting wiring schemes between fixtures in my house...perhaps you might find the same.

Even if you don't do the continuity checking, just seeing how the fixtures are wired might be helpful.

Just my $.02

Drew
 
  #14  
Old 11-28-05, 02:34 PM
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Now that I am starting fresh, today (first post today to anybody) - I think we need to go back to the beginning and start anew. You had everything working before you fiddled in the basement. Obviously you undid a needed wire.

Why are we bothering trying to diagnose a switchbox/2-light fixture set up that WAS working, until you fiddled with the basement wiring.?

You need to get THAT back right - I would think. Unless you can clear up the whole story for us.

THEN see if you have neutral back at the switchbox once again (my guess is that it was correct, before you moved that basement wire), so that you don't have that weird situation where the switches grounding on the metal switchbox has to complete the circuit.

Plus you haven't explained the whole story as to why you did the basement wire job/for dining room light and whether or not you are now using one of the switches in the switchbox you drew, to power the dining room light. You are not saying if the two switches still go to the TWO? outside lights? One outside light per each switch? Or, was it one switch to the two outside lights and one switch already WAS for the dining room light? Where exactly are these light fixtures located that you drew in relation to the switchbox and each other. I need a mental image on all this.

So that people here don't waste our time when trying to help people, things need to be explained very clearly and every possible known thing mentioned.

I actually love and thrive on good mysteries. But I don't like wasting time either with unknowns, where they COULD be made known.

Recently, I was able to talk a fellow handyman through an electrical job he flubbed up after he de-wire nutted piles of wires in a basement than ran all kinds of things. Over the phone, I was able to tell him how every wire had to be! And I did this over the phone, sight unseen. I even 'knew' which black wires had to be nutted to white wires. Also, recently, I used detective work to figure out where I lost a neutral to an outside porch light and GUESSED and was right that there was a plastered over switchbox (no way by looking at the wall would you have known. It was intuition based on no liiving room light or switch for a living room light, nor a second switch for a switched outlet, yet they had a porch light switch inside the door.) and a plastered over ceiling lightbox junction, and those areas probably contained a bad connection. And I was right. I broke through the wall and actually found hidden wires and found the bad connection. So I am able to do this stuff. But I have to have more necessary information. And I could probably say everybody else here trying to help does also.
 

Last edited by ecman1; 11-28-05 at 02:53 PM.
  #15  
Old 11-28-05, 04:36 PM
dcohalla
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old house switch box wiring

Quote: "Also there's not much slack with these wires in the box -- maybe 3" on each --"

As a side note, that seems to have been a popular way to do things "way back when." I too have found in almost all my boxes very short wires/connections. Makes it damned near impossible to redo/undo without pigtailing... and as you have probably found out, there just isn't much room in some of those old metal boxes.

With regard to the problem starting after you undid the basement wiring... I think that's your most likely culprit. Like was mentioned before, sounds as if you have disturbed a neutral somewhere.

If I get into a pickle about why it's not working, it helps me to draw a diagram, similar to what you have done. However, I find it helps to draw the whole circuit-- from panel to fixture/appliance. Label each wire w/color and line, load, neutral, or ground, etc... usually before I have finished the drawing the answer jumps right out at me I am a visual/kinestetic learner though... so YMMV.

Keep us posted.

--Drew
 
  #16  
Old 11-29-05, 07:04 PM
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Nice thread folks. I ran into a similar deal over the summer at my sister's 1920s house and didn't have the time or the right tools to deal with it, like a VOM. First things first, this is a dangerous situation and you would be wise to get an electrician to make it right.

That said, fixing this is a weekend project for the layman. That is, one weekend to diagnose and one weekend to rewire.

I suspect the original problem a long time ago was figuring out how to make a two-way circuit into three-way, or adding separate switches to distant fixtures without having enough hot wires between the various points. The original house wiring possibly brought the hot into the chandelier or one of the other ceiling boxes from which your other lights are powered. Later modifications used a white wire for a hot.

A diagram that helps explain the situation is in Ray Mullins' book Electrical Wiring Residential, 13th ed, page 135, Figure 5-31. The applicable code is NFPA 70 200-10(c) and 200-11. Sorry I don't have a digital camera right now to photograph it, but the basic idea is to keep a downstream device hot at all times and allow two 3-way switches and the fixture that they control in midstream, while only using two wires for the entire run.

I would recommend that you diagram the whole mess. Shut off all circuits appearing in all affected junction boxes and open up every box where the circuit in question appears. Draw a complete diagram and after double- or triple-checking that you have all the power off, use a VOM to verify the paths. When you've verified your diagram see if you can figure out which device was added later.

To make your installation safe, you will probably have to add wire somewhere or live without a switch or fixture.
 
  #17  
Old 12-03-05, 03:57 PM
pbillante
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Thanks all for the troubleshooting help. Using the various techniques suggested I was able to isolate, trace, and identify a route for a neutral back to the panel and correct the problem in the switch box.

Essentially, the dining room chandelier's box had a disconnected cable from part of a prior demolition which I converted into a neutral (after testing) and followed it forward to the switch box and back to the panel. So, the switch box is now using a real neutral instead of using the box and cable sheath as the neutral return.
 
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