New led lamps glow when switched off

[RobTi]

Just removed the central ceiling light and fitted 3 led down lights, but didn’t have any lamps to hand, so I fitted 3 old coloured led gu10 ones, now no dimmer fitted just a standard switch but the lights are dimly glowing when off

 

[bernardgreen]

When the switch is OFF the capacitively coupled power from Live to Switched Live is enough to "glow" an LED lamp.

A dimmer often draws some curremt through the lamps when OFF.

The solution is to provide a by-pass around the lamp for this capacitively coupled power.

A capacitor in series with a resistor across the supply to the LED will in almost all cases solve the problem. The capacitor absorbs the capacitively coupled power without the voltage being high enough to affect the LED.

0.1 microfarad 400 volt capacitor polyester and 100 ohm 1 watt resistor have proved sucessful. I would also fit a 1 amp fuse in series as well

400 volt as it has to cope with the approx 320 volt peaks of 230 v AC It cannot be an electrolytic or polarised capacitor.

Contact suppressors such as the one below provide the necessary circuit in a single convenient package. The use across LED lamps is not their intended purpose but they do provide the function required.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0209241

 

[RobTi]

will it be okay for tonight will get new lamps tomorrow or should I just disconnect for tonight ?

 

[SUNRAY]

I've seen this arrangement,especially in new builds several times:

One house basher has told me it's the main reason he does the Neutral joint at the switch rather than loop in at the rose.

 

[bernardgreen]

It will not do any harm left over night.

 

[bernardgreen]

OUCH, Having Line and Neutral either side of a change over switch can result in a prolonged plasma arc when the moving contact moves from Live to Neutral.

The arc is created between Live and the moving contact when the moving contact breaks the circuit. This arc must extinquish before the moving contact reaches the Neutral.

With some modern switches the amount of movement may be less than the 3 mm required to break the arc.

 

[RobTi]

Okay plumber talking here, ex council house which was required aroun 30 years back no neutral at switch at ceiling I have 3 neutrals I to connector block and another neutral with a red sleeve into another connector block

 

[bernardgreen]

another neutral with a red sleeve

A black or blue wire is not always Neutral, the red sleeve suggests that black or blue wire is a Switched Live or maybe a Permanent Live.

 

[SUNRAY]

OUCH, Having Line and Neutral either side of a change over switch can result in a prolonged plasma arc when the moving contact moves from Live to Neutral.

The arc is created between Live and the moving contact when the moving contact breaks the circuit. This arc must extinquish before the moving contact reaches the Neutral.

With some modern switches the amount of movement may be less than the 3 mm required to break the arc.

In which case they don't conform to current regs and should not be being installed.

When I sorted my 2 way + intermediate system I used the above method but inserted a resistor between neutral and switch, I probably wouldn't bother with a resistor the next time.

 

[SUNRAY]

Okay plumber talking here, ex council house which was required aroun 30 years back no neutral at switch at ceiling I have 3 neutrals I to connector block and another neutral with a red sleeve into another connector block

So the black with red marker sleeve is more likely switched live and the most effective (and cost effective) method is Bernards 'Snubber' circuit.

 

[RobTi]

Update popped A couple of lamps from another room and these work okay as they are only a year old so must have been the old lamps