Interior Ceiling Lights Problem

[Tigersden]

2012 Big Country 3450 TS has two rows of lights in ceiling and one switch for each row (labels read "kitchen" and "living")

1. Noticed that wall surface near switch felt warm but lights were working. Shortly thereafter neither switch would light.

2. Confirmed that fuze #2 in fuze panel (ceiling lights) was good. I noticed that, with the fuze removed, the red indicator light opposite the fuze glowed brightly when the light switch(s) were in off position. Same light glowed dimly with switches in on position (grounding problem somewhere ??).

3. Removed the wall switch and checked voltage across terminals on both switches (which are mounted together in a single plastic housing). Voltmeter showed 12.5V across both when either switch was in the off position. Read 0 volts with switch in off position which is what I would have expected. Checked the voltage on a nearby similar switch (which is working fine) and found it to be the same 12.5V.

4. Pulled wiring out from wall to confirm that wiring was twisted tightly within wiring nut.

Any suggestions about what I should try next?

 

[danemayer]

Hi Tigersden,

First of all, I'm assuming other 12V stuff is working ok - like bedroom and bathroom lights, refrigerator, thermostat, etc. If all 12V systems are out, you have a different problem.

If the fuse is not blowing, and you have 12.5V at the switch, but the lights don't come on, it sounds like a wire carrying 12.5V is open on the way to the string of ceiling lights, or the ground coming back to the fuse panel is open.

Try measuring voltage at the first light fixture. If you have 12.5V there, you likely have a problem with the ground wiring. In that case, I'd check for a loose wire on the backside of the fuse box. The ground wires all tie into screw-down terminals on the back.

If the 12.5V is not present at the first light fixture, you're losing it somewhere on the way to the ceiling. Look for a wire nut near the switch or near the first light fixture. If you find them, check voltage with the wire nut taken off. Make sure the wires are making good contact.

 

[RuralPastor]

Bill, it sounds like a defective switch or supply to the pair. Resistance builds up heat--which opens the circuit--then cools down and closes. I would change it before it gets too hot. Ideally, the fuse should protect the wire from overload, but loose connections can be dangerous. If not the switch, then the problem seems to be a loose connection somewhere in the circuit. Mark

 

[Tigersden]

Thanks Dan - I'll try this and let you know how it turns out.

 

[cookie]

I agree with Mark, you may have a bad switch or two.
I would jumper the two wires on the back of the swich and see if the lights come on.
If you had any bad wiring, you would not see 12 volts across the terminals of the switch. There would be no path to neutral.

Peace
Dave

 

[brianharrison]

There is a switch on the light fixture as well (on the end). I had a situation where the dear wife switched off both pairs of lights at the fixture.

Barring that, and assuming they are fluorescents, if one tube burns out and I have had the ballast not able to power the other older one. Try two new bulbs, then change out ballasts once you have determined 12V supply through wall switch, at fixture, at ballast, at pin connections for tubes.

Brian

 

[Tigersden]

Well, I guess I have exceeded my personal capabilities for resolving this - I have an appointment to complete warranty work so I will have this looked at by the pros at that time.

My thanks to all who have responded with suggestions.

 

[wdk450]

Maybe I misunderstood your voltage readings across the switch, as they seem wrong. Reading ACROSS a switch that is OFF and has 12 volts power supplied, and a ground at the end of the load, I would expect to read 12 Volts. If the switch is ON, the switch contacts act as a short between the two probe points, and you should read 0 Volts. BTW, if the load side wiring is open or the ground is bad, you will read 0 volts across the turned OFF switch.
Now if you are reading voltages to ground, with the switch OFF you should read 12 volts on the supply wire to the switch, and 0 volts on the load wire from the switch. With the switch ON you should read 12 volts at both wires of the switch.