How to fix LED fixture not turning off completely when the switch is off - Page 1
Forum section: electronics / beginners

author: drakejest
author_rank: Regular Contributor
timestamp: February 05, 2022, 08:06:13 am
content: I have LED ceiling lights that are not completely turning off even when the switch is off.Sometimes the brightness of the glow is just to much for me and finally decided to do something about it.tried to explain what is going on but did not offer a solution on how to fix the issue. The pcb on8:11looked really similar to what mine uses. The solution to the problem though is on anothervideo by Electroboomsaying to place a 470K ohm resistor on the output of the rectifier.The circuit that electroboom is using is not the exact same circuit as i have. So will it still work? and how do i calculate the value of the resistor for my circuit

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 05, 2022, 05:12:56 pm
content: I think an additional load value has to be a size or bit higher than parasitic leakage. I don't know but I would start with 0.5-1 mA possible value of a leakage current. 1 mA is 220-240 kOhm for 220-240 VAC.I don't think there is a strong need to disassemble a lamp, you just may put resistor in parallel with a whole lamp.Some people use film caps, for example X2 type, about 10-100 nF. They waste much less active power than a resistor but still make a load.

author: drakejest
author_rank: Regular Contributor
timestamp: February 05, 2022, 06:07:15 pm
content: Quote from: Vovk_Z on February 05, 2022, 05:12:56 pmSo there is no specific value then as the wires on a room could have a very higher parasitic leakage than on another room.Quote from: Vovk_Z on February 05, 2022, 05:12:56 pmThe power supply is on an external enclosure, so it is very easy access, and i think this is the best place to put it also so there is no splicing on wires.Quote from: Vovk_Z on February 05, 2022, 05:12:56 pmHmm X2 is not in the search filters where i am buying from (lcsc.com). There are 600V+ rated Polypropylene Film Capacitors (CBB). Will that do? Also what value would be the most 'catch-all' value?I will need to order different values else shipping cost will bankrupt me. The components are very cheap anyway.Is the difference of the amount of wasted power between the cap and and resistors great? A 1.2ma leeak would waste about 1/4 Watt of power, that seems a lot. I do not know how to model the film caps into my simulation though so i cant tell how a capacitor would do. How is it connected? parallel between L and N ?

author: Zero999
author_rank: Super Contributor
timestamp: February 05, 2022, 06:22:51 pm
content: A capacitor theoretically wastes no power at all, since it has no resistance. In reality, it will use some power determined by the resistance of the capacitor and cable.The power can be calculated in a resistor using Ohm's law.P = V2/RI'd use a 10nF capacitor, based on what I know about the capacitance of cables. 600V should give plenty of margin for 230VAC operation.

author: themadhippy
author_rank: Super Contributor
timestamp: February 05, 2022, 07:36:55 pm
content: Or a neon indicator across the lamp terminals.

author: drakejest
author_rank: Regular Contributor
timestamp: February 06, 2022, 08:30:50 am
content: Quote from: Zero999 on February 05, 2022, 06:22:51 pmSo is a capacitor better? wont the resistor be guaranteed way of controlling of how much the leak will be? or its a thing that a 10nF capacitor will do the job the same but waste less power?

author: Zero999
author_rank: Super Contributor
timestamp: February 06, 2022, 08:54:09 am
content: Quote from: drakejest on February 06, 2022, 08:30:50 amEither a resistor, or capacitor will work. A capacitor will not waste as much power, as a resistor.

author: drakejest
author_rank: Regular Contributor
timestamp: February 06, 2022, 01:32:29 pm
content: Quote from: Zero999 on February 06, 2022, 08:54:09 amI do not understand how the capacitor is able to solve the problem could you please explain it to me? Are we relying on the internal resistance of the capacitor for it to work?I forgot to ask how is the capacitor connected>? is it in inline with the live terminal or parallel between live and neutral?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 06, 2022, 02:06:01 pm
content: You switch your light on/off using a solid state device? If you use an ordinary switch I can't see how the LED stays on.

author: Zero999
author_rank: Super Contributor
timestamp: February 06, 2022, 02:13:35 pm
content: Quote from: drakejest on February 06, 2022, 01:32:29 pmA capacitor works on the same principle as a resistor. It passes a small current determined by its impedance.Z = 1/(2πFC)Where:Z is the impedance in OhmsF = frequency HzC = capacitance Farads.The capacitor doesn't dissipate any power because the current leads the voltage by 90º, so when the current is at the peak, the voltage across it is zero and power = v*i. The capacitor charges and discharges, causing power to be transferred between the capacitor and back to the mains again. The net power dissipation is ideally zero, yet in reality it's a tiny amount due to the resistance in the wiring.Here's a simulation showing the power dissipation in a 10nF capacitor connected across the 240V mains (a peak voltage of 340V). Note the phase shift between the voltage and current and that the power dissipation cycles between positive and negative, as power is transferred to and fro between the capacitor and the mains. The average power dissipation will be zero. I've included a resistor for comparison. Note how the power dissipation in the resistor is always positive and the current is in phase with the voltage.Look up power factor.QuoteIn parallel with the LED lamp.

author: themadhippy
author_rank: Super Contributor
timestamp: February 06, 2022, 02:51:09 pm
content: Quotecapacitive coupling in the switch cable,if you wire your lighting circuit so the feed loops in and out to the switches problem solved.If however you loop your feed in and out at the light fitting with a switch line from celling to the switch on the wall,as was standard in uk domestic wiring until recently, the switch cable acts as a capacitor and lets enough current through to tickle the leds

author: radiolistener
author_rank: Super Contributor
timestamp: February 06, 2022, 03:22:01 pm
content: Quote from: drakejest on February 05, 2022, 08:06:13 amjust remove neon lamp from the switch and issue will be solved.

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 07, 2022, 04:35:35 am
content: X2 caps are placed in the "Suppression Capacitors" group at lcsc.

author: drakejest
author_rank: Regular Contributor
timestamp: February 08, 2022, 01:49:31 pm
content: Quote from: Zero999 on February 06, 2022, 02:13:35 pmAhhh i get it now ! so basically the capacitor will draw power by charging itself and the charged power will be pushed backed to mains so ideally i am not billed for anything since the power consumed is returned back to grid. Unlike a resister where the consumed power is turned to heat.Quote from: themadhippy on February 06, 2022, 02:51:09 pmCan you please rephrase is it so that i can understand it a little better, so that i will be aware where to properly place the switch in the circuit? As far as i know how its done in my place is itsLive from the breaker -> long wire to switch -> long wire to LED lights -> long wire Neutral to back to breakerQuote from: radiolistener on February 06, 2022, 03:22:01 pmNo neon light on the switch. it does have glow in the dark plastic which is not electrically connected in any way.Quote from: Vovk_Z on February 07, 2022, 04:35:35 amOhh thank you ~! lcsc has some very cheap stuff but their search filters are so terrible you have to really know what you are looking for. When i typed x2 a few days ago it said it didnt exist. which i have quite a few similar experience in the past.What are X2 by the way? there are also X1 caps. I would assume X2 are better? There is even a Y2.

author: themadhippy
author_rank: Super Contributor
timestamp: February 08, 2022, 03:02:17 pm
content: Quotemaybe.The above is the almost standard way uk lighting circuits were wired for years.Wire A (loop in )goes to the fuseboard,wire B (loop out ) goes to the next light and wire C is the switch wire.The problem is wire c always has one conductor live, and the way the cable is made it acts like a capacitor so a tiny bit of current bleeds across,often enough to cause the leds to glow slightly.One solution is to wire the lighting circuit so the loop in (wire A ) and loop out (wire b) go to the switch,not the light fitting ,getting rid of the long switch wire (c) and instead running a cable from the switch to the lightAn added advantage is it also brings the neutral to the switch which can be usefull in the future

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 08, 2022, 11:09:04 pm
content: Quote from: drakejest on February 08, 2022, 01:49:31 pmYou don't need neither X1 nor Y1/Y2. Use an X2 cap, in parallel with a lamp.

author: drakejest
author_rank: Regular Contributor
timestamp: February 11, 2022, 04:24:26 pm
content: Quote from: themadhippy on February 08, 2022, 03:02:17 pmthe second image really made it all understandable for me, So what im getting that is to minimize the length of wires that doesnt have a neutral along with them. It would be best that all Live wire should a acompanying neutral traveling along with them.

author: drakejest
author_rank: Regular Contributor
timestamp: February 11, 2022, 04:25:28 pm
content: Quote from: Vovk_Z on February 08, 2022, 11:09:04 pmCan you tell me what those rating means ? like for example if you were to rank them from best to worst where would X2 be and what would be at the top?

author: drakejest
author_rank: Regular Contributor
timestamp: February 11, 2022, 05:14:51 pm
content: Quote from: Zero999 on February 05, 2022, 06:22:51 pmIf i could not get a 10nF capacitor, is it better get the next value that is higher?

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 11, 2022, 08:45:36 pm
content: Quote from: drakejest on February 11, 2022, 04:25:28 pmlink #1link #2link #3link #4I don't rank them. I just use X2 caps in between the line and neutral. X1 caps are usually rare or unobtainable so they are not cheap. And similar thing with Y1/Y2 caps - easily obtainable ones usually have small rated capacitance, so they are mainly used when capacitance is lower than 10 nF in places where there is really a need for Y-class type.If you want to rank them then you may rank them by Peak Impulse Voltage - the highest value is 8 kV for Y1 caps.