Light Fault

[m4tty]

Hi,

Was at a customers house wiring new immersion and testing cable - all ok.

Asked to check a front room light which wasent working. First checked at dimmer switch to see if live which it wasent then dropped the light fitting to see what was up there. Just a single cable with live neutral and earth. Voltalert fluke pen showed live but mft proved it was dead.

Why did the fluke voltpen show live when it's range is 200v upwards and the mft proved it was dead?

After I told the nice lady the floorboards are gonna haveto be lifted to find the junction box she told me that her daughter had a playstation dancemat in the room above and the light fitting started flickering then it went all together. So it must be a loose connection in the jb in the ceiling . Any thoughts ?

Cheers

 

[Manator]

Possible JB connections, but I would not rule out cable damage. The cable may just run above the joist in a notch, the dancemat placed above it, then the constant jumping has damaged that cable. Be careful because the cable may well still be live, hence the Volt stick picking up the presence of a voltage.

 

[SPECIAL LOCATION]

Volt pens can pick up all sorts of strange fields to make them illuminate..

Maybe a ring main cable just the other side of the ceiling board not far from your volt pen?

Or is the break in your circuit in the neutral at a hidden box..

i.e.

Live cable = 230v

Lamp = 230v

Neutral = 230v

break somewhere further along the neutral leg..

Volt pen = Glow

Meter between L&N 230v - 230v =0v?

maybe?

:coffee

But I spose you are going to shatter my theory and say you were testing between an Earth NOT L&N!!? X(

 

[Manator]

+1^

 

[m4tty]

Thanks for the reponse guys. The light fitting when dropped had over 2 meters of cable up in the ceiling so when fitting lowered it was nearly on the floor. The voltpen picked up voltage about a meter from the floor mid room so not much chance of a nearby ring main cable but thanks for teaching me that one for future. Also i tested between l-n and l-e and n-e, got 0V on all. Thanks again

 

[batty]

Fluke voltsticks are usually realiable I would take an earth off a nearby socket and then test with a voltage tester at light you may have dropped a neutral and earth somewhere it does sound like dancemat has something to do with fault.

 

[chrishaworth]

It's fairly common for some of the lighting circuits in an old building to have a cpc but for the supply to the lighting JB to be missing it. I'd agree with the neutral being disconnected and be very careful with the line conductor.

Cheers. Chris

 

[Evans Electric]

Don't forget , M4tty, Voltsticks will light up on anything , can be very useful but you have to follow up with a tester.

They are great for locating a cable , say from a bunch of T&Es , with someone flicking the breaker on & off.

 

[ProDave]

If your volt stick light up, my bet as already suggested, is a lost neutral (from that junction box)

Check voltages with a meter and wander lead from known good neutral.

Or a neon screwdriver :coat

 

[SLIPSHOD & SLAPDASH]

Fluke voltsticks are usually realiable I would take an earth off a nearby socket and then test with a voltage tester at light you may have dropped a neutral and earth somewhere it does sound like dancemat has something to do with fault.

Ditto, that will also test the Rcd (if fitted). I recon it could still be live but a broken neutral and no earth

 

[xrford]

Voltsticks can even pickup static if you rub them over jumper or clothing quickly...handy at times but definitely stick with your meter, at first i thought the wiring through the fitting may have broken or come loose but still doesn't explain loss of volts...