Light Problem

[tatom]

In the kitchen, I have a 2 foot florescent tube. One night I noticed when the light was turned off, that on one end, there was a faint glow. Maybe there is some power leaking to the tube? Any ideas?

[Beacher]

I get the same sort of thing happening. I have 3 circular florescent lights in my living room and when I turn them off at the wall switch, 2 of them will remain glowing -- not just at the end but all through the lights. The only way I can get them to turn off completely is to switch off the breaker that feeds that circuit. I've just always assumed that it was caused by crappy substandard and ungrounded wiring, but if anyone can shed some light (so to speak) on the actual reason it's happening, I'd sure like to know.

[trogers]

Replace the starter. It's a small round cylinderical thingy inserted into the fixture near to one end of the tube. Twist and remove it.

[Tywais]

Usually it's due to the light switch is switching off the neutral and not the hot side of the power. In other words, incorrect wiring.

[Beacher]

Replace the starter. It's a small round cylinderical thingy inserted into the fixture near to one end of the tube. Twist and remove it.

Thanks for the advice, and I know the part you're talking about, but I don't see why enough power to keep the lights illuminated should still be getting to them when I turn them off using the wall switch. To my logic, once I flip that switch at the wall, no power at all should reach them. Please don't interpret that I don't appreciate your advice or I'm being difficult to deal with, I just don't see how replacing the starter will help.

[trogers]

There is some remaining power in the ballast (or transformer) for a short period of time after power is turned off. It's a defective starter that is letting power to flow to the tube and causing the glow. I do not think it is defective wiring.

[Beacher]

There is some remaining power in the ballast (or transformer) for a short period of time after power is turned off. It's a defective starter that is letting power to flow to the tube and causing the glow. I do not think it is defective wiring.

Thanks again, but these suckers don't glow for a short period of time, they'll keep glowing forever if I don't kill the power at the breaker.

[Tywais]

Thanks again, but these suckers don't glow for a short period of time, they'll keep glowing forever if I don't kill the power at the breaker.

As I mentioned above, the hot side is not being switched off at the power switch but the neutral. This leaves the hot side connected to the ballast and as such to the tube. It takes very little current to activate the phosphors in the tube and side wall leakage through the glass to the environment (air) which is at ground potential can cause it to glow.

[Beacher]

Thanks again, but these suckers don't glow for a short period of time, they'll keep glowing forever if I don't kill the power at the breaker.

As I mentioned above, the hot side is not being switched off at the power switch but the neutral. This leaves the hot side connected to the ballast and as such to the tube. It takes very little current to activate the phosphors in the tube and side wall leakage through the glass to the environment (air) which is at ground potential can cause it to glow.

Thanks for this. So, what is the solution? Can it be easily fixed by taking off the switch plate and doing something simply there?

[lopburi3]

Yes but it is better to have an electrician do it. You may have to turn on power to find which line is hot feed if wires are hidden and you would need a testing screwdriver or volt meter to do that.

Another thing that can happen is shorting in feed wire making both wires hot - had that happen when a rat bit through wire so both were bare and enough power crossing to make lite stay on regardless of which wire was being switched. That took me awhile to figure out and did not trip RCD because it was not a ground loss and not normally enough to trip the breaker.

[Beacher]

Thanks all.

I think I'll get the building engineer to look at the situation again and ask that he check some of the things mentioned.

[Crossy]

A bit late, but I'll chime in with another vote for a switched neutral. If it's not then there is something seriously wrong with the wiring that requires looking at pronto!

You can easily check by using your trusty neon-screwdriver to find the hot in your light with it switched on, this hot should go away when you turn off the light.

You will either need to fix it at the switch or at the ceiling depending upon which way the switch was wired. Your sparks will should may might probably won't know how to fix it

[Beacher]

A bit late, but I'll chime in with another vote for a switched neutral. If it's not then there is something seriously wrong with the wiring that requires looking at pronto!

You can easily check by using your trusty neon-screwdriver to find the hot in your light with it switched on, this hot should go away when you turn off the light.

You will either need to fix it at the switch or at the ceiling depending upon which way the switch was wired. Your sparks will should may might probably won't know how to fix it

Thank for injecting a bit humor into this thread.

I'm afraid that the one choice you didn't cross out seems to be true. I explained the situation to him as he nodded his head, appearing to understand. After explaining, he left and gave me the impression that he was coming back with a voltage meter to check the hot and neutral wiring. Instead, I saw him cleaning the pool 10 minutes later, and he's never come back.

I've got my own solution, anyway -- now I simply use the circuit breaker switch as my light switch. No real problem, and besides, it feels more authentically Thai doing it that way.

[Daffy D]

I have the same with our circular ceiling fittings, they glow ever so slightly all night when switched off. As "Crossy" and "Tywais" already mentioned it's the way the switching is wired.

I've lived in many places over the years and in the majority of cases the switches are nearly always on the negative side. Is this a local cultural thing?

I believe in wiring the switch to the live feed so you don't have all those hot wires running round the house just waiting for a chance to do some mischief.

[longball53098]

Switching a circuit on/off using a breaker as the switch is not a recommended practice unless you install a breaker designed for this use. Also what other lights/plugs are you switching when you do this? Seems a bit inconvenient to me.

As to the "culture" of why it seems so common to mix the neutrals and the hots? Just poor training and education and not caring to check the work when it's complete. The tradition and culture of passing a method down from one person to the next. In a lot of cases they don't know there is any difference. A wire is a wire just connect them and magic the lights come on.

[Beacher]

Switching a circuit on/off using a breaker as the switch is not a recommended practice unless you install a breaker designed for this use. Also what other lights/plugs are you switching when you do this? Seems a bit inconvenient to me.

As to the "culture" of why it seems so common to mix the neutrals and the hots? Just poor training and education and not caring to check the work when it's complete. The tradition and culture of passing a method down from one person to the next. In a lot of cases they don't know there is any difference. A wire is a wire just connect them and magic the lights come on.

Ya, I'm not crazy about the idea of using the circuit breaker as a light switch, but the lights and outlets that are turned off are exactly the ones I want turned off, and the breaker is right above the light switch, so it's not too inconvienient.

As for truly solving the problem, should I kill the power to the wall switch and simply try reversing the wires that are connected to the switch?

[tatom]

After 10 years with a common Issan "fuse box" (a knifeswitch and 1 buse fuse), I got an electritian to install a ground rod and a real fusebox with breakers. The first night, I noticed all the lights had a glow. I called the electritian and he came over and switched the hot and neutral wires in all the switches, problem solved.

It seemed strange to me, but I dont know anything, just that it worked. The reason I started this thread is because now one of the lights is glowing again. I dont think switching the wires is the answer, but then again, what do I know?

[Crossy]

As for truly solving the problem, should I kill the power to the wall switch and simply try reversing the wires that are connected to the switch?

Nah, sadly it doesn't work like that

There are several ways of wiring lighting and dependent upon which has been used where you go to fix it changes.

The first task is to make sure the problem really is a switched neutral. You'll need a neon-screwdriver, the type that lights up on a live wire when you put your finger on the end. You could use on of those battery operated VoltSticks that don't actually need to touch the conductor to work.

At the FIXTURE

1. With the light ON determine which of the incoming wires in the fixture is live (you may need to get creative if it's all taped joints)

2. Turn the light OFF, the live should go away. If it does not or both connections are now hot you have a switched neutral.

OR

At the SWITCH.

1. With the light OFF. ONE of the switch terminals should show live.

2. With the light ON. BOTH should show live, if both show dead with the light on it's a switched neutral.

[tatom]

I only have a problem with the 1 light and my electric bill is only 300 bt a month, so, is there any reason I shouldnt just leave it?

[Crossy]

I only have a problem with the 1 light and my electric bill is only 300 bt a month, so, is there any reason I shouldnt just leave it?

1. That glow from the end of the tube is annoying.

2. The potential danger, even with the light off the wires in the fitting will kill. Not an issue until you want to change the tube.

As always, UP2U

EDIT As noted above. TASK-A find out if it really IS a switched neutral