FLASHING L E D

[DARREN47]

Hi new to all this forum stuff. I'm wondering if any one has come across this following problem and resolved it

wired 2 banks of downlights with 3 core and earth (2 switch lines and shared neutral) switch closest bank on and one light on other bank starts to flash not faulty wiring or fitting

the light fittings used are collingwood fire led 9watt

rang collingwood was informed that would have to change wiring to resolve not realy an option without causing very large expense to myself

 

[Doc Hudson]

Welcome to the forum Darren47, I think you have already had the correct answer by telephoning the manufacture. It sounds like an induced voltage issue along the shared cable. What level of electrical knowledge do you have, (DIY/qualified electrician)? Do you understand the concept of AC voltages being induced into adjacent conductors?

Doc H.

 

[kme]

The issue is with the shared neutral, as suggested above - causes issues with LED loads.......n.b. can also happen with low energy CFL lamps, especially at the top of stairwells, when there is a long switch cable.

KME

 

[rugbymacc]

agree with all the above

....... doesn't take much induced voltage to get these things lit, due to their low energy consumption.

 

[Andy™]

if its really a problem, put a neon from a fused spur in parallel with the flickering lights

 

[peter.smith]

Hello....newbie subscriber here, just Googled the problem and found this forum. Bought 3 Collingwood 9 watt fire led lamps yesterday, 17/09/2010, to replace 3 x 50 watt halogen low voltage devices. Fitted them, and was firstly amazed - so close in light output, a far cry from the units of only 12 months ago. Had the same problem, though, they flicker when switched off. I'm an electronics engineer, so I considered the problem, decided it may be due to capacitance in the wiring - have 2 spco switches and 2 intermediates along a corridor, so a long wiring run. Did some measurements....Fluke Scopemeter in record mode confirmed these things trigger at 78volts, can see the voltage rise gently, then lamps flash & voltage returns to under 30 volts, cycle repeats. Tried Andys approach (above) but neons usually trigger at 180 volts, so this didn't work here. I found a 270 k resistor across lamps seems to limit this rising voltage and cures the problem - works, but I dont think its ideal. These things must run off fresh air, and have very efficient switch mode converters on them. Your comments invited, but I am not convinced by the 'shared neutral' and other wiring theories. New type of low capacitance cabling needed maybe?

Pete

 

[Doc Hudson]

Interesting observations Peter, welcome to the forum. May I ask where you took your reading across, is at the LED fittings or the supply cable? Other thoughts re capacitance issues, as all circuits and loads on the whole installation are parallel back to the supply, potentially could these problems be originated at other parts of the installation?

Doc H.

 

[batty]

I have found in past when low energy stuff flashes its because people have cut cpc's off. Had this with one over a bed and it was because the switch cable had been extended but had no cpc in it it was only about a foot of cable and this was enough to induce a voltage and lamp would flash on and off. Probably differnt with led stuff but a possibility.

 

[DARREN47]

[quote name='Andy

 

[DARREN47]

hi peter sorry missed your post last week i think the issue is with the fittings because once fittings are disconected the voltage is gone.The voltage measured when fittings are connected starts at 49volts rises to 70+ volts then discharges through led tried neon didnt work.have used fittings in other rooms without any problems unless wired with 3 core (2 switch lines and 1 neutral)and same happens . i find it strange that its the bank of lights furthest from supply that has the problem and not the closest

 

[SPECIAL LOCATION]

...... i find it strange that its the bank of lights furthest from supply that has the problem and not the closest

I am unclear on you logic that shorter cable runs from supply would be more susceptible to the problems?

Surely the longer cables will have greater capacitance effect between the two parallel conductors..........

and

a longer wire would also have a greater chance of picking up induced voltages from adjacent cables?

no?

SO longer cable runs more likely to get the problem than the shorter ones?

or has me electrical science head fell off back-wards again?

:|

 

[Lurch]

I am unclear on you logic that shorter cable runs from supply would be more susceptible to the problems?

I was a little confused at first as well, took me a minute to digest it first time round when I was passing through, thought about it on the way home and was going to add something.

 

[steptoe]

I think he was on the logic that closer to the CU would have more juice,

ALA a hose pipe.

not thinking about a hose with lots of little pin holes,

ie the further away(longer) the hose is then more water will be spread out from it.

 

[DARREN47]

thanks for my quick lesson on capacitance of cables but i think your missing the bigger picture my lights are still flickering

 

[Andy™]

thanks for my quick lesson on capacitance of cables but i think your missing the bigger picture my lights are still flickering

go fit something with a filament.

 

[Doc Hudson]

thanks for my quick lesson on capacitance of cables but i think your missing the bigger picture my lights are still flickering

I would have to disagree there, the bigger picture surely has to encompass the likley causes of your problem. Such as the points that have been highlighted in the above posts, also by the fitting manufactures in your original post. It is most likley a wiring problem due to inductive or capacitive effects along the cable runs. Until you address this I can only imagine you lights will continue to flicker.

Doc H.

 

[Andy™]

just a thought, but if its 1 way switching, you could take a neutral to the switch connected to L2, perm live to L1 and sw live to lights to com. this will connect switch live to neutral when not in use, and get rid of any inducted voltage

 

[muffin]

lol that made me think when i first seen that done, perm live in l1 and sw live in com, neutral in l2 just as a connector. different but why not.

sorry but this sort of thread annoys me.

please help.....

sorry, not interested in any replies.....

please help....

 

[Lurch]

lol that made me think when i first seen that done, perm live in l1 and sw live in com, neutral in l2 just as a connector. different but why not.

Saves a trip to the van when you forget to pick the connectors.

sorry but this sort of thread annoys me.please help.....

sorry, not interested in any replies.....

please help....

I'm not saying anything, other than most people will just ignore it an move on. I usually say something to provide the OP with a bit of advice on forum etiquette, but it's too unfriendly apparently so it's frowned upon.

 

[DARREN47]

have resolved it

i rewired them