Wikipedia:Reference desk/Archives/Miscellaneous/2024 October 4
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October 4
[edit]Light flickers when turned off
[edit]Our restrooms now have light switches thet glow when turned off. I noticed that if I turn off the light and shut the door so it is dark, the light flickers just enough to see it slightly faster than once a second. I assume that with the light switch off, the light has no power. Is it that the glowing light switches periodically send electricity to the light or is it a sign that the switch is broken. Note, all of the bathroom lights on these switches flicker. In the back office where they don't have a glowing switch, it doesn't flicker. So, I am certain it is something to do with the fancy glowing switch. For clarity, by "glow" I mean that the rectangle of plastic around the switch is like a little orange light that turns on when you turn the switch off. 68.187.174.155 (talk) 15:25, 4 October 2024 (UTC)
- Maybe a motion sensor? ←Baseball Bugs What's up, Doc? carrots→ 23:04, 4 October 2024 (UTC)
- A light switch has two contacts that can be "closed" (bridged) to close an electric circuit that includes the electric lights. While the circuit is open (switch is "off") there is a voltage difference between these two contacts. This can be used to power a sentinel light, and also an electronic circuit that produces pulses that periodically close the circuit briefly. --Lambiam 06:03, 5 October 2024 (UTC)
- Why would the same style lights blink ever so slightly when on a glowing switch but not blink at all on a regular switch? (If that is what you answered, I'm sorry that I simply don't understand your answer.) I've been searching and what I've seen claims that there is a capacitor in the bulb that causes a slight flicker depending what else is on the circuit, but again, that is the bulb. If the bulb flickers, the bulb flickers. In this case, the bulbs only flicker when using the new switches that glow when turned off. Searching, this looks exactly like the kind of switch we have, but I can't claim it is that specific model. 68.187.174.155 (talk) 12:25, 5 October 2024 (UTC)
- First off don't trust me one bit on wiring, if you aren't comfortable enough to have already pulled the switch to see what's happening probably best to get someone to fix the problem for you. These are LED lamps that are flickering correct? Incandescent bulbs can run off alternating current, they are just heating up and glowing, light-emitting diodes need direct current to work. The driver circuit will convert household AC to DC, and you can see a photo of the circuit on that page. That looks like a capacitor to me in the very center, and here is someone disassembling a $1 LED lamp to look at the circuit, which looks to me to have a bog-standard rectifier and Capacitor input filter.What's probably happening is stray voltage is charging that capacitor which will eventually reach a high enough voltage to power the rest of the circuit which will then discharge the capacitor. So not 'flickering' but 'flashing' at your regular interval of slightly faster of 1/sec.Another possibility is that you might have a dead-end switch where the wiring first goes to the fixture and then to the switch. I think this might cause this problem with a lighted switch and LED lamp but not all all sure. Another possibility is that you have older wiring which does not have a ground wire or the ground to this circuit could be faulty. Without popping the switch and testing things the simplest way to solve the problem would be to replace at least one of the bulbs which are on the switch with an incandescent. You might try a different make of LED bulb and it might solve the problem or at least give a different flashing rate for variation. fiveby(zero) 22:51, 5 October 2024 (UTC)
- The OP is talking about multiple lights in "our restrooms", so presumably at his/her place of employment. I doubt that he/she is in a position to start taking the light fixtures and switches apart or replacing the bulbs. The best practical option would be to ask for an explanation of this (probably normal) phenomenon from the establishment's Facilities Maintenance Department*.
- (*That's what it would be called in the UK, where I used to work in that sector; doubtless it will be something different in the US. I'm talking about qualified electrical (& mechanical) engineers, not janitors who can change a light bulb.) {The poster formerly known as 87.81.230.195} 94.6.86.81 (talk) 00:23, 7 October 2024 (UTC)
- You are correct. I am referring to public restrooms in a library, which have new light switches installed. Before the change, I never noticed the faint blinking of the lights and the same type of lights are not flashing on the old switches that do not illuminate. I believe the answer is that the circuitry inside the switch that makes it glow also causes the circuitry inside the light bulb to periodically charge up and flash the bulb. This isn't really a problem as anyone who enters the restroom will likely turn the light on right away and never notice the flashing. It was just a curiousity. I would bring it up with maintenance, but they are located at the main library, not our remote branch, so I rarely see them. I'm not really certain when they came in and swapped out the switches. 68.187.174.155 (talk) 17:54, 7 October 2024 (UTC)
- At the American community college where I work, "Maintenance" are the people who are qualified to work on the switches while "Facilities Management" are the janitors. --User:Khajidha (talk) (contributions) 13:15, 9 October 2024 (UTC)
- The last UK Facilities Maintenance company I worked for (at a client's large manufacturing and administration site) either directly performed, or sub-contracted and controlled, services including catering (the site had a large canteen), grounds maintenance, civil engineering (i.e buildings repairs, maintenance and refurbishment projects), electrical and mechanical maintenance and repairs (of everything except the client's specialist manufacturing machinery), HVAC maintenance and repairs, running the on-site power plant, porterage, internal and external postal distribution, cleaning (i.e. janitorial services), pest control, organising visits of external inspectors (for example of of lifting equipment, water systems and and cooling towers), manufacturing effluent disposal, and a great deal of entering data concerning all the above into the client's work records system. {The poster formerly known as 87.81.230.195} 94.6.86.81 (talk) 04:35, 10 October 2024 (UTC)
- First off don't trust me one bit on wiring, if you aren't comfortable enough to have already pulled the switch to see what's happening probably best to get someone to fix the problem for you. These are LED lamps that are flickering correct? Incandescent bulbs can run off alternating current, they are just heating up and glowing, light-emitting diodes need direct current to work. The driver circuit will convert household AC to DC, and you can see a photo of the circuit on that page. That looks like a capacitor to me in the very center, and here is someone disassembling a $1 LED lamp to look at the circuit, which looks to me to have a bog-standard rectifier and Capacitor input filter.What's probably happening is stray voltage is charging that capacitor which will eventually reach a high enough voltage to power the rest of the circuit which will then discharge the capacitor. So not 'flickering' but 'flashing' at your regular interval of slightly faster of 1/sec.Another possibility is that you might have a dead-end switch where the wiring first goes to the fixture and then to the switch. I think this might cause this problem with a lighted switch and LED lamp but not all all sure. Another possibility is that you have older wiring which does not have a ground wire or the ground to this circuit could be faulty. Without popping the switch and testing things the simplest way to solve the problem would be to replace at least one of the bulbs which are on the switch with an incandescent. You might try a different make of LED bulb and it might solve the problem or at least give a different flashing rate for variation. fiveby(zero) 22:51, 5 October 2024 (UTC)
- Why would the same style lights blink ever so slightly when on a glowing switch but not blink at all on a regular switch? (If that is what you answered, I'm sorry that I simply don't understand your answer.) I've been searching and what I've seen claims that there is a capacitor in the bulb that causes a slight flicker depending what else is on the circuit, but again, that is the bulb. If the bulb flickers, the bulb flickers. In this case, the bulbs only flicker when using the new switches that glow when turned off. Searching, this looks exactly like the kind of switch we have, but I can't claim it is that specific model. 68.187.174.155 (talk) 12:25, 5 October 2024 (UTC)