Simple task - right? Wrong!!

[K8MHZ]

My sister showed me a light switch in her garage that she had to wiggle the handle a little to make the lights stay on. It was a 3 way with it's mate in the house. Obviously a burnt contact in the switch.

Simple swap, right?

Wrong.

I pulled out the old switch and all the terminals were the same color. I couldn't ring it out because it showed open all around when the switch was in one position due to the burnt contact.

OK, no problem, I will just figure out which wire has a load on it. I found it and connected that to the common. Turned power back on and to make sure of things, yes, new switch works great. Then I went in and turned the switch in the house off. Switch in garage wouldn't turn lights on. Double checked, switch in house is a 3 way. So I look to see how the garage switch is wired. Now, in addition to this switch, there was also unswitched loads. I could hear the refrigerator running and it stayed on when the lights were off. The overhead only had three wires, not enough for a switched three way along with an unswitched circuit. The messenger wire was not part of the circuit and wasn't grounded. To make things more fun, the wires on the outside of the garage were spliced to a white, a black and a blue. Inside, I had no white. I had red, black and blue. After some serious head scratching I figured out the 'white' wire was actually the red wire bleached white by the sun.

So I decide to check to see which terminals are hot with my trusty Greenlee tick tracer, which works VERY well. When the lights were on, there was no indication of power at all from my tracer. Also no 'real' voltage at all from white wires in box to any terminal when the lights were on using my DVOM.

Now am I really cornfused. So I start hand tracing cables and lo and behold, right next to me I find a fuse panel totally obscured with stuff hanging in front of it. It was fed from the bottom. That explains how I got the switched and switched circuits. It also provided me with a for sure neutral, not just a white wire I was hoping was a neutral.

Re-checked. When lights were on, no voltage from switch to N on any terminal. When lights were off, 120 on all terminals to N.

Then a light in my head comes on. I have seen this before. Using a hot terminal in the fuse box, I verified my suspicion. The switch was switching the neutral, and the hot was present all the time at the lights. This was verified by my tick tracer.

So that is another piece of the puzzle. But what about the fact that the inside switch was only working as a single pole?

Since I was more concerned about the switched neutral, I got my sister to the garage and showed her, using the tick tracer, that there was still a hot wire at the lights when they were OFF and I needed to come back and fix that. I also told her I had to figure out why the inside switch all of a sudden stopped working like a 3-way.

She thinks about it for a minute and says, 'It's always been like that.' At least as long as she lived there.

When I go back to fix the switched neutral issue, I think I will make a video of the strange voltage readings a switched neutral can produce, and how such a scheme affects my trusty tick tracer. It's pretty bizarre seeing a voltage reading disappear when the load is switched ON and come back when it is switched OFF.

Also, my DVOM read the usual phantom voltages on the circuit so I am going to also bring along my solenoid tester and show how it is not tricked by phantom voltages.

This was a fun one. Although a bit frustrating, it was a good mental workout on a nice spring day.

 

[ptonsparky]

Worked on more than one "it's always been that way" usually after I fix it and figured out there was NWIH it had been right for some time.

 

[JFletcher]

My sister showed me a light switch in her garage that she had to wiggle the handle a little to make the lights stay on. It was a 3 way with it's mate in the house. Obviously a burnt contact in the switch.

Simple swap, right?

Wrong.

I pulled out the old switch and all the terminals were the same color. I couldn't ring it out because it showed open all around when the switch was in one position due to the burnt contact.

Dont most 3 ways (that arent dimmers) have the two travellers directly across from each other? If you had continuity between two terminals in the non-burnt position, the terminal w/o another on the opposite side would generally be the common.

And I got fooled by a switched neutral once, lit me up like a Christmas tree. my NC tester showed nothing, I broke the neutral wires, got hit putting them back together..wth? So with them broken (it was a fixture j-box), I now have power on one of the neutrals... put them back together under a wire nut, nothing.

Good story tho Mark. Enjoyed reading it. I played trim carpenter today, made more mistakes in one room putting in quarter round shoe molding than a carpenter probably makes in a year haha. Cut long and recut if need be, inside and outside corner measurements can be tricky. At least it wasnt crown that needs compound cuts....

Look forward to the video. and yes, it was (and still is) beautiful here.

 

[K8MHZ]

Worked on more than one "it's always been that way" usually after I fix it and figured out there was NWIH it had been right for some time.

Back when I was working on cars I had one in that I had to do an entire dash pull in order to fix the heater. When I got it all back together, my 'road check' revealed that the wipers wouldn't come on. So I called the lady that owned the car, told her it was back together and when I had the issue about the wipers figured out I would call her so she could pick up her car.

About 20 minutes later, a young man shows up and wants to pick up the car, which belonged to his mother. I explained to him that after I got the dash back in, the wipers wouldn't come on and that's what I was dealing with.

The kid looked at me asked why, since they hadn't worked since they bought the car.

Turns out the shafts were seized in their housings. Which made trying to find an electrical problem keeping the wipers from working a ball.

:rant:

 

[templdl]

This usually happens to me as I was just about to walk out the door to go home. "Oh, I forgot to ask if you could take a look at this or that." And you do and.....

 

[K8MHZ]

Dont most 3 ways (that arent dimmers) have the two travellers directly across from each other?

So far, yes, and that is how I wired it and got it right the first time. But then, just when you 'assume' you know how things are 'always' made, you run across one that's different. In fact, these two were mirror images of each other.

Also, remember that when I got it hooked up, it didn't work like it should have (because of the other switch) and that made me suspect of my assumption.

But I did get it right the first time.

 

[ggunn]

This usually happens to me as I was just about to walk out the door to go home. "Oh, I forgot to ask if you could take a look at this or that." And you do and.....

It happens to me just about every time I am about to walk out the door to go on vacation.

 

[growler]

Then a light in my head comes on. I have seen this before. Using a hot terminal in the fuse box, I verified my suspicion. The switch was switching the neutral, and the hot was present all the time at the lights. This was verified by my tick tracer.

Did they mean to swith the neutral or is it possible that polarity just got revered by accident somewhere before feeding the light ? It would end up being the same except unintentional.

 

[K8MHZ]

Did they mean to swith the neutral or is it possible that polarity just got revered by accident somewhere before feeding the light ? It would end up being the same except unintentional.

It could be either. The house is old and has been added on to more than once. Way back in the day, it was commonplace to switch the neutrals. I have seen it more than once, but always in homes that are older than I am.

 

[kwired]

My guess is you have what once was a "Carter three way" between the house and garage. Your mentioning of only three conductors between the house and garage yet also having unswitched loads in the garage gave that away as soon as I read it. It may not be wired correctly anymore but probably what was initially there.

I've seen this a few times on old remote buildings that had power years ago. You bring L1 and L2 to the "traveler" terminals of the three way switches - also gives you unswitched 120 volts in the remote building. The third wire between buildings is from the common off the three way in the main building. Both commons hit the light on the remote building and it is on when opposing polarity is presented, off when both sides are same polarity. Is no longer code allowed mostly because the shell of the lampholder is not always connected to the grounded conductor, but there are a few other issues no longer allowing this switching method anymore, plus it was done before equipment grounding conductors were even heard of.

 

[growler]

So I start hand tracing cables and lo and behold, right next to me I find a fuse panel totally obscured with stuff hanging in front of it. It was fed from the bottom. That explains how I got the switched and switched circuits.

My guess is you have what once was a "Carter three way" between the house and garage. Your mentioning of only three conductors between the house and garage yet also having unswitched loads in the garage gave that away as soon as I read it. It may not be wired correctly anymore but probably what was initially there.

Yes but he goes on to explain that he finds a fuse box that is being fed from a different circuit. This explains the unswithed load.

These overhead conductors could be a hot and two travelers with the power originating in the garage ( fuse panel ).

 

[kwired]

Yes but he goes on to explain that he finds a fuse box that is being fed from a different circuit. This explains the unswithed load.

These overhead conductors could be a hot and two travelers with the power originating in the garage ( fuse panel ).

I missed that and was assuming three wires from the house was all that went to the garage. This had me thinking that was only way to have a three way from house plus an unswitched load in the garage.

After reading again I caught this: "When I go back to fix the switched neutral issue, I think I will make a video of the strange voltage readings a switched neutral can produce, and how such a scheme affects my trusty tick tracer. It's pretty bizarre seeing a voltage reading disappear when the load is switched ON and come back when it is switched OFF." Don't know if that is throwing him off for some reason but that would be normal when dealing with a switched neutral.

Open the switch(es) and you have an extension of the ungrounded conductor through the load, touch that conductor and you will get a shock if you are not insulated from ground. Close the switch and it is now solid connection to the grounded conductor and the voltage drop is across the load.

 

[K8MHZ]

After reading again I caught this: "When I go back to fix the switched neutral issue, I think I will make a video of the strange voltage readings a switched neutral can produce, and how such a scheme affects my trusty tick tracer. It's pretty bizarre seeing a voltage reading disappear when the load is switched ON and come back when it is switched OFF." Don't know if that is throwing him off for some reason but that would be normal when dealing with a switched neutral.

To those that have experienced a switched neutral and realized that's what they are dealing with, the voltage readings seem 'normal'. It's those readings that made me look into the possibility of a switched neutral and that's what I found.

I didn't mention it in my first post, but there were also phantom voltage readings of 40 - 70 volts. I would like to demonstrate the differences between a DVOM and a solenoid tester when dealing with them.

To those that have never had the pleasure of dealing with a switched neutral, the voltages I mentioned would indeed seem 'bizarre'.

Also remember that besides the switched neutral, there is a three way switch in the house acting like a single pole, so in one position neither of the travelers have the required (in this case) neutral. That gives some interesting voltage readings at the garage switch, too.