2 way lighting wiring fault

[Francophile]

Hi, first time post.

I wonder if someone could save my sanity.

Changed lamp for a LED one and discovered it was glowing slightly even when "off".

Turns out 50v there at all times.

Wont bore you with fault finding and running of new cables.

Eventually I have temporarily run in new live and neutral from the consumer unit.

New cable between switches. Switches are fine.

I still have 50v..have tried a second meter and anyway the LED is on still.

What with City losing (in injury time again) and now Spurs winning this weekend can't get much worse!

 

[mikep]

I would try disconecting each switch just to see if the 50volts goes, may be leakage across one of them, or inductance on the switch wires as you don't need anything at all to light led's.

Isolate the 3 core and Earth from the main drop cable see what happens then to work out if it's on the drop or the strappers.

My bet it's inductance.

Mike.

 

[NozSpark]

you have what is called capacitive coupling..

It's basically the switch cables are picking up an induced voltage from adjacent cables; a normal incadesent lamp dumps the current (which is very small) to neutral; ; IIRC you can fit a 2uf capacitor across the L & N at the fitting to stop it.. wait for confirmation from someone else before you do this though!

 

[bengie]

we found a similar problem at work a few years ago with phillips CFL lamps, every 30 seconds or so they would give a 1/2 second flash and it was just what the man above said, basically electricity getting lnduced into an adjacent cable(thats how transformers work don't you know).

 

[mikep]

I had a Worcester boiler which kept firing up, 80volts on the switch wire, wired in a small bulb to dump the inductance, phoned up bosch they actually fitted a capacitor on the SW L to stop it being too sensitive.

put the old bulb back in.

Mike.

 

[Evans Electric]

What they said + didn't someone posted on here recently that a certain make of light switch was passing a voltage when off ???

 

[Francophile]

Thanks for all the help chaps.

Guess I'll be putting a traditional lamp back in!

Had convinced myself there was neutral fault somewhereheadbang

Kind of wish I'd asked two days ago before I demolished half the house....

Tried telling the OH it needed decorating anyway... :innocent

Think you need a "doghouse" smile!

 

[batty]

Always ensure cpc's are connected, had this on a job cpc was not connected on a joined cable were switch had been moved this was enough to make low energy lamp in bedroom go on and off intermitently.