weird house wiring problem

[Inspector507]

Danny,
Yes that is a back-fed switch or a switch loop ( makes a loop at the switch and comes back). They will work that way even though I would have made the white coming down the hot feed. But yes it will work that way.

 

[Mosey]

Thanks for the help so far! This has been frustrating. I was expecting the hard part to be pulling a new wire through without having to bust up the drywall, so once I got that done I thought I was headed down easy street. Thank goodness for wire fish tapes! The wiring was supposed to be much easier than all this. Anyway, it may be a few days before I get any more done on it, but I’ll let you all know what I find out.

 

[beenthere]

Is running a hot wire to a switch on a white wire according to code? I learned to keep the black hot until after a switch, such as Mosey pictured. I also thought code now says to paint the switched-white black or wrap it with black tape at both ends to indicate it is or can be hot.
(Like Mark in NH's Dad taught him)

 

[MossRoad]

It is a common practice to do it the way it was pictured as long as you mark the white wire with black on each end. The wire is considered hot all the way to the light, where it picks up the neutral. All it is is an extension of the black hot wire before it gets to the light fixture. You will probably find that any house that supplies the feed to ceiling lamps by way of the attic is wired like this.

 

[Inspector507]

beenthere,
There was no code "requirement" to do it that way or any other way. But it was, and still is common practice (at least in my area of the US). The National Electrical Code changed in 1999 to require the installer to idenitfy that white wire as an ungrounded conductor. You can still do it that way as long as you re-indentify it.

 

[PTRich]

I have helped people repair wiring in many old houses before. Some houses used "spider webs" in the attic for hot feeds to the lights and supplied a ground thru a switch for lights, a very dangerouse method. When ever I "fix" wiring in old houses now I replace everything, that way I know it is done right, all the way from the panel to the box. In houses that are very bad I have put in a sub panel for all replaced wiring (I like very neat and orderly panels). You may want to check your oringional wiring, It may be 14-2 because it is just a light. I would use 12-2 for a fan (in fact I use at least 12-2 in everything now).

PTRich

 

[Inspector507]

PTRich,
14-2/with ground is fine as long as you observe the loading and over-current requirements

 

[MossRoad]

That's the way we did it. I put in a sub panel off the old piece of junk and moved all of the major appliances to that with all new wiring. Then I started moving the lighting circuits. When most of the stuff was on the new box, I had a disconnect switch installed under the meter and the feed switched from that to the new box. Then the old box became a sub panel and I am slowly removing the rest of the old lighting circuits from that. We went with 12 also.

 

[Mosey]

I did get a chance to work on this a little bit last night. I got some new switches and did the same ohm-meter tests that I did with the other new switch. I connected one lead of the ohm-meter to the “+ LINE +” (the screw with a black coating on it) side of the switch and the other to one of the switch terminals on the other side (no label and it’s a bright brass colored screw). When I turn the switch on, it goes to 0 ohms, like it should. When I turn the switch off, it goes to infinity, but not right away, it gradually goes up and takes about 12 seconds to get to infinity. All of the new switches behaved the same way. So, I don’t think there is anything wrong with the switch, although there’s still the possibility that I have the wrong type of switch for my application. I called the company that makes the switch, Eagle Electric in NY, 800 441-3177 and talked to a guy named Nick and told him which switch I have, 271W-BOX Combination 2 Single Pole Switches. I told him what it did when I tested it with and ohm-meter and he said the switch was probably bad and to return it. So, he doesn’t really know what’s going on either!

I also did some double checking in the bathroom, with the original switch still in place. With the switch turned off, it reads 125V from the black wire to the metal box (ground) and 0V from the white wire to the metal box. With the switch turned on (light comes on), it reads 125V from the black wire to the metal box and 125V from the white wire to the metal box. With the switch turned off, it reads 125V from the black wire to the neutral side (longest slot) of the plug that’s in the bathroom (which is on a separate circuit) and 0V from the white wire to the neutral side of the plug. With the switch turned on, it reads 125V from the black wire to the neutral side of the plug and 125V from the white wire to the neutral side of the plug. So, it must be wired correctly. If the light was wired backwards, with the switch turned off I would have 125V from the white wire to the neutral side of the plug. Do you agree?

I also got a hold of my brother (who has been out of town in my time of need!). He build and wired his house with the help of his father-in-law who is an electrician. My brother is also stumped.

 

[Inspector507]

Danny,
The present wiring does sound correct. I have no idea why the new switch doesn't work.

 

[PaulT]

While I'm sure no electrician, it seems like some information is missing to solve this mystery. I have never read any postings regarding how the light is currently (no pun intended) wired. Danny, you previously said you were assuming how the hot and neutral was being supplied from a junction box. Are you sure that there is a junction box in between the three wiring locations (switch, light and panel)? Since you said there is only one wire in the switch box, I think we can all assume it "back fed". I would recommend examining the wires that are feeding the terminals on the light as your next step, followed by looking in the junction box, if indeed there is one in between. Is it possible that the old switch has hot isolated from ground (somehow), and the new switch has hot closed to ground? If neutral and ground are crossed somewhere else in the circuit, wouldn't that cause this behavior?

 

[Mosey]

I’m not 100% sure if the junction box is there like I assume. The cable from the light does not go to the switch box, it goes off in another direction (toward the breaker box). The cable from the switch goes off in the same direction. My next step is to dig around some more in the blown in insulation and find that junction box, if it exists, and take a look inside.

 

[Mark_in_NH]

The power from the panel ( or somewhere else ) is coming into the exhisting light fixture. It has to, in order for the light to pick up the neutral.
The electricity is coming down to the switch on the Black conducter in the romex, it is then traveling back to the light fixture on the White conducter.
The new switch, which is merely, 2 stacked single pole switchs receives power for both switchs, from usually one source. You can seperate this ability or function ( if so desired ) by removing the break away tab between the 2 dark colored screws.
If Danny installs his Black conducter to one of the dark colored screws and the White conducter (which is called the switch leg) to one of the brass colored screws, for either the top or bottom switch, then in all proper electrical theary and assuming the switchs are functioning properly, the light should work just fine.

 

[Inspector507]

Danny, the light has worked all these years with the old switch in place, and I see nothing that makes me think the wiring is incorrect. No matter whether there is a junction box buried or not, the ohm-meter readings you took should be correct also. That leaves one thing, the switch. Buy another brand of switch, making sure it is a combination switch with 2 single poles. Put your "hot" feed on the side with the dark coloring, marked LINE. Put the return on the other side. There is no reason that won't work.

 

[Mosey]

Good suggestion Jerry. Now comes the disadvantage of living out in a rural area. The small city (Columbus, IN) where I work and shop (mostly at Lowes!) doesn’t have much to choose from. Lowes only has this one brand. In the last 5 years, Lowes has run the 2 hardware stores (Ace and True Value) and 2 lumber stores (Wicks and Wolohans) out of business. Walmart has basic switches, but not these double ones. We’re supposed to be getting a Menards next year, but at this point I’ll have to wait until I get a chance to run to either Seymour (20 miles south) and try the hardware store there, or Greenwood (suburb of Indy) and go to a Home Depot or Menards up there.

 

[heehaw]

my bet is on a bad switch!!
heehaw

 

[MossRoad]

You said that when you put in the new dual switch, exactly like the old switch, just to test it, the light stays on even if you flip the new switch to either side, correct?

I know this sounds stupid, but have you tried flipping the other switch? Or tried flipping all the combinations of both the switches? Maybe the terminals are not next to the switch that they are suppossed to operate. Maybe the terminals are joined together somehow. Anyway, if the original switch was an on/off switch, and the new switch is an on/off switch, it has to work. It is just that simple.

Once I had a switch that was supposed to be 3-way switch and it was really an on-off switch. That caused lots of troubles. There are not two doors to this bathroom anywhere, are there?

 

[AndyR]

It may be worth your while to spend $30.00 on one of those circuit tracing probes. They work by plugging in (or wiring in) a signal source module and the using a detector module to find the wire in the rat's nest of your particular situation. Still sounds like something funky /w3tcompact/icons/crazy.gif going on with your existing wiring.

 

[ByuBill]

I am definately not an electrician, don't even understand half of what was said in these post. In your very post you said something that caught my eye. <font color=blue>From the ground on the switch to the box, it read 125V!</font color=blue> I am not sure that anyone other than PaulT picked up on this. I just can't for the life of me ever remember seeing a switch with a ground ( green ) screw on it. Maybe I have missed something along the way./w3tcompact/icons/hmm.gif I do have a switch in my bathroom like you are wanting to install. Only it also has a third switch for a heater. Just to check, I took it out and looked. Nope, no ground on it either. All of the bare wires are twisted together inside the box (plastic box) My question, Do you have a three way switch?

 

[Inspector507]

ByuBil,
If your switch in the bathroom is more than 2 years old or so, it may not have a place to connect the ground to it. The Code changed in 1999 to require all switches to be grounded, "bout time.