LED light, switching /earth issue

[Philip Porter]

Hi,

I have an LED landing light, which has 9 G9 LED bulbs. The unit has two switches, one upstairs and one downstairs. Ive found that when the upstairs switch is in the closed circuit position, but the light is off due to the downstairs switch being in the open position, there is still a very small current going to the bulbs. Try this the other way around and there is no illumination at all. My first thoughts were around the earthing resistance for the downstairs switch, which i intend to measure with my multimeter to check that, other than this i think that it could be due to long wiring runs and the cables being close next to each other. Anyone experienced similar? Whats the best course of action for this? Im trying to avoid running another separate cable if possible, due to just having decorated.

Many thanks in advance
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[Vortigern]

Two thoughts: Use a snubber, switch the strapping cables around. More likely to be a snubber though.

 

[SparkyAndGeorge]

Hi there have been many discussions on this subject on these forums. Look up 'capacative coupling' and read up on it. First of all, try changing the lamp to a reputable manufacturer such as Crompton or Phillips.

 

[Philip Porter]

Hi there have been many discussions on this subject on these forums. Look up 'capacative coupling' and read up on it. First of all, try changing the lamp to a reputable manufacturer such as Crompton or Phillips.

Thanks, just had a look, ive got the same bulbs in two other downstairs hall lights and no issue there, again one of those downstairs hall lights has two switches, only difference is the distance as far as I can tell so capacitive coupling seems likely.
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Two thoughts: Use a snubber, switch the strapping cables around. More likely to be a snubber though.

Thanks for that, ill certainly give this a go.

 

[Lucien Nunes]

Agree that a snubber network may be the easiest solution; it simply absorbs the small capacitive leakage current to prevent it lighting the lamps.

With 2-way switching there are no open or closed positions; the two switches change over between L1 & L2. When the lamp is off, one or other of L1 & L2 is at the same potential as the common terminal. If the strapper cable between the two switches is triple and earth, then two of its insulated cores are adjacent (hence have greater capacitance) and one is spaced away from the other two by the CPC (hence has less). Thus the capacitive leakage current past the switch will depend on whether the two adjacent cores are at the same or opposite potentials, which in turn depends on which of the two 'off' permutations is selected.

There are other similar possible causes with different cable configurations.

 

[marconi]

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