House wiring question

[Farmhand]

House wiring question: The main stairwell in our house has a light at the top of the stairs and another at the bottom of the stairs. The light at the bottom of the stairs has been intermittently going dark and coming back on. I replaced the fixture but the problem continues. I removed the switches at the top and bottom of the stairs, cleaned them with Deoxit and the problem continues. Granted, the switches are several decades old. I’ll try replacing the switches, but I wanted to ask all of you if you’ve run into this and what you think the issue might be. Worst case scenario, I’d have to pull new wires. I really don’t want to do that in 102-year-old house.

 

[teal'c]

I'd try a different bulb.

 

[Bill Ashton]

Farmhand, does your house still have knob-and-tube wiring? Might be time to consider pulling those wires! My home is about 110 years old, and we are slowly gutting her room by room. Found gas pipes in the wall. Some old Romex type wires, but in one case "someone" had been chewing on them

Knob-and-tube isn't unsafe per se, but any conversion between it and Romex might be, plus the fact you have no ground wire, a pretty big deal. Good luck!

 

[Grenadeslio]

Another thing to look at. Only with the power off, look inside the light socket, see the tab at the bottom? That's the hot, the outer screw shell is the neutral if wired correctly, sometimes they are reversed but for this fix that's another issue.

Often the bottom point of a light bulb is just a blob of solder, some are larger than others. Some in fact are so large they crush the tab at the bottom of the light fixture socket so flat that subsequent lamps make poor contact. This usually leads to constant premature lamp failure in the light fixture while others last much longer, even if on the same switch etc. This arcing can also damage the light socket, if so it needs replacing. If not, then just bending the tab back up so it's no longer crushed flat to the bottom usually fixes this sort of problem.

Of course there's always the chance the conductors in the wall and or ceiling are defective, but easiest things first.

If the lighting is fluorescent then ignore the above unless Edison base like a standard appliance bulb, EI: screw in compact fluorescent lamps.

 

[Farmhand]

I changed out the entire fixture hoping that would solve it. The current wiring is not knob and tube. I haven’t found any in the whole house fortunately. I will replace the switches and see what happens. If all else fails , I’ll hire an electrician.

 

[Grenadeslio]

I changed out the entire fixture hoping that would solve it. The current wiring is not knob and tube. I haven’t found any in the whole house fortunately. I will replace the switches and see what happens. If all else fails , I’ll hire an electrician.

Ya, the mad cow missed that entirely.

 

[roger2]

Wires don't go bad. Joints inside electrical boxes can and do go bad.

Try a different bulb first as suggested by teal'c. But most likely it is either the switch or the joints (connections) inside the box that the intermittent fixture is mounted to.

You didn't mention whether the two lights in the stairwell are tied together. If they are, and if both switches operate both lights, and if only one fixture is failing, then the switches are not the problem. But if the bottom fixture is solely controlled by the bottom switch, then a new switch is the next thing to try after a different bulb. Really, the switches should be replaced regardless just because of their age. New switches are not expensive at all. The cheapest ones are less than a buck, but do go for something above bottom-of-the-line and you will only be out a couple bucks.

If not the bulb and not the switch, then very likely it is the wiring joints inside the box. Re-doing those joints is often a tedious task. Usually there are too many wires crammed into too small a box. Sometimes the wires are cut-off too short, making them difficult to work with. And insulation on older wires can contain asbestos and/or it can become brittle and easily cracked when twisting on wirenuts.

If you do get to the point of re-doing the joints inside that box, pictures posted here would be helpful.

 

[Alobar]

Since you replaced the fixture it has to be either the lamp (you didn't say you replaced that) or the switches or the wire connections. If the 2 switches are a 3 way system I would replace both of them. Also do you have a multi meter? Check for power first at the switch, and light. (carefully) Could be a loose connection on a neutral too, so tighten that as well. Don't assume a white wire is a neutral and visa versa.

 

[Grenadeslio]

Are the lamps incandescent, fluorescent, LED?

 

[Alobar]

I should also mention be careful around open neutrals. If you grab a open neutral and inadvertently touch a ground while the circuit is otherwise energized you can get lit up. Ask me how I know!

 

[SeniorSteve]

The original poster says the light at the bottom of the stairs goes out intermittently. Nothing was mentioned about the light at the top of the steps. If in fact the light at the top of the steps is fine, it would rule out the switches as that would affect BOTH lights. The lights have to be connected in parallel which would mean there are two wires, (and a ground) going between the top lamp and the bottom lamp boxes. I don't know if the power is introduced at the top or bottom, but it should be only in one place. My guess would be a loose wire nut in the upper lamp box.

Edit: just read roger2's post above, I must have missed it. He described how I was thinking.
Thanks Roger,
Steve

 

[Alobar]

The original poster says the light at the bottom of the stairs goes out intermittently. Nothing was mentioned about the light at the top of the steps. If in fact the light at the top of the steps is fine, it would rule out the switches as that would affect BOTH lights. The lights have to be connected in parallel which would mean there are two wires, (and a ground) going between the top lamp and the bottom lamp boxes. I don't know if the power is introduced at the top or bottom, but it should be only in one place. My guess would be a loose wire nut in the upper lamp box.

My 2 cents
Steve

Good point!

 

[biscuithead]

The original poster says the light at the bottom of the stairs goes out intermittently. Nothing was mentioned about the light at the top of the steps. If in fact the light at the top of the steps is fine, it would rule out the switches as that would affect BOTH lights. The lights have to be connected in parallel which would mean there are two wires, (and a ground) going between the top lamp and the bottom lamp boxes. I don't know if the power is introduced at the top or bottom, but it should be only in one place. My guess would be a loose wire nut in the upper lamp box.

Edit: just read roger2's post above, I must have missed it. He described how I was thinking.
Thanks Roger,
Steve

I’d hazard another guess...

It sounds like a three way switch situation.
Gotta find out if it is fed below or above, then follow the switch-leg. Also need to see if they drug a neutral through both boxes. It could be a problem of a dropped neutral. Maybe a neutral splice in a switch box, if neutral is present.

Whenever I’ve trouble-shot an issue like this it is always the neutral , and that is always the last consideration.

Electrician is needed, or lots of luck.

 

[Farmhand]

It is a three way switch situation. It’s also a situation where the boxes are two small, the wires are tw short and incredibly stiff, and that probably is an asbestos jacket. I’ll try to make time to take everything back apart and get some pictures.

 

[Grenadeslio]

It is a three way switch situation. It’s also a situation where the boxes are two small, the wires are tw short and incredibly stiff, and that probably is an asbestos jacket. I’ll try to make time to take everything back apart and get some pictures.

The insulation will most likely be brittle and crumble off when you mess with the wires. Just be prepared for a more extensive repair than you think it's going to be.