50v on ceiling rose live when switched off

[m4tty]

Hi,

Been round a neighbors house who's hallway ceiling rose is showing 50v l-e and 50v l-n when the light is switched off. I tested it with my mft and got the same results. Is this inductance? It makes the energy saving bulb flicker after it's turned off for a while. I think it's induced voltage ? What do you guys recon?

If it is, can I take a reading from an analogue meter? I've got a robin sa9083 which I could try or am I barking up the wrong tree.

Cheers

 

[ProDave]

Try the analogue meter, a lot less prone to spurious readings.

50V L-E is quite feasible due to leakage or induced voltage.

But my suspicions are aroused by 50V N-E That should not be. So some checks needed. What's N-E reading in the CU? if that's reading 50V there's some bigger problems here. What sort of earth?

And if N-E is NOT 50V at the CU, then there's some big wiring problems with the light.

 

[m4tty]

Thanks for replying Dave it's not 50v n-e it's 0v n-e. Inductance from another cable ?

 

[ProDave]

Thanks for replying Dave it's not 50v n-e it's 0v n-e. Inductance from another cable ?

Oops, sory I misread you. Hope I haven't caused confusion.

Yes it's probably leakage or induced voltage. Try the analogue meter and see.

Is it a damp house? could even be damp in the switch. Might be worth trying a replacement switch.

Finally, with the lamp removed and switch turned off, try an IR test on the switched live.

 

[Andy™]

probably inductance as above

 

[Revved Up Sparky]

Have you tried isolating all other circuits and just leaving that lighting circuit energised?- to see if it makes any difference to the reading?.

What about the continuity of the cpc ? r1+r2/ Zs. I've had some weird voltages on lighting circuits- and sometimes found that the cpc had no continuity and thus there was no earth path back to the CU.

 

[m4tty]

Have you tried isolating all other circuits and just leaving that lighting circuit energised?- to see if it makes any difference to the reading?. What about the continuity of the cpc ?.... what is the r1+r2 / Zs?.

I will do these tests and report back my findings. Thanks mate

 

[Evans Electric]

I'd be interested in the answer to this TBH. 50v between L - N

You wonder if the switch is tracking across or dampness in switch box. Lets face it , if that switch is off , 3mm gap and all that , the damn lights should be brown bread.

Customer fetched me back to a similar problem , job I had done in their bathroom , GU10 downlights flickering when off .

Customer had replaced the plastic ferrule on the end of the pull switch cord with a really heavy polished marble thing which was almost closing the switch but not quite.

 

[Manator]

The strange ones are the best.

 

[Evans Electric]

Hey Prodave , you've turned green !!

 

[wozz]

If you have a martindale voltage indicator that will tell you the truth.

 

[m4tty]

Cheers wozz ain't got one of them tho what about a fluke t100? Will that lie to me too lol?

 

[SPECIAL LOCATION]

]

Hey Prodave , you've turned green !!

Watchout.... you may have made him angry..

Thats what happened to the.......

"INCREDIBLE HULK"

isn't it?

:C opcorn

 

[batty]

I'd be interested in the answer to this TBH. 50v between L - N You wonder if the switch is tracking across or dampness in switch box. Lets face it , if that switch is off , 3mm gap and all that , the damn lights should be brown bread.

Customer fetched me back to a similar problem , job I had done in their bathroom , GU10 downlights flickering when off .

Customer had replaced the plastic ferrule on the end of the pull switch cord with a really heavy polished marble thing which was almost closing the switch but not quite.

Standard switches don't have the 3mm gap thing only double pole ones I have always thought if we did used double pole switches on lights it may save a bit of electric but probably barking up the wrong tree

 

[Andy™]

3mm gap only needed if its designed as an isolator, not just functional switching

most switches are probably only 1 or 2mm at most

 

[Evans Electric]

[quote name='Andy

 

[m4tty]

Ive been back to this house again today and tested with an analogue meter a Robin SA9083 MK18 and there is definitely 50V on the line conductor at the ceiling rose when switched off. Am going to change the switch at the bottom of the stairs for a normal switch as the current one has a timer and photocell built into it which switches the light on when it gets dark and may be letting voltage through when switched off? If this doesnt work what else can you suggest to find where the voltage is coming from.

I could try switching other CPDs off to see if the voltage disappears?

Also the guy who lives there asked me to ask on here if its been costing him money as if 50V has been sitting there trying to light the incandescent bulb up but not succeeding has this been consuming power?

Thanks

Matt

 

[steptoe]

volts are free,

its the amps that cost you money,

turn off the main switch, you still have 230v at it, but NO amps.

 

[m4tty]

volts are free,its the amps that cost you money,

turn off the main switch, you still have 230v at it, but NO amps.

Can you expand on that a little please steps cant get my head round it being abit thick lol

 

[steptoe]

until you start putting a load on then NO electrons(?) move, so no energy being consumed,

think of a hosepipe, there is water in it, but until you open the nozzle no water is being used.