lighting fault

[Noob2013]

Hi all,

I have a strange lighting fault which I'm trying to get my head round. I popped in to a family members house on the way home from work so didn't have a Meggar. However, i had a multimeter and also carried out an inspection and test on this property a couple of months ago and found no problems.

The fault is on the kitchen/dining lights. There is 4 x GU10 3 spot fittings (fitted with the LED GU10s) There is a 2g switch, each switch supplying 2 lights.There are 2 t&e's at the switch (perminent and switch for each set).

Whenever either switch in the kicthen was switched on the mcb trips.

On arrival, several led lamps had physically burnt out and in a right state! Removed all lamps and still tripping!

Disconnected one light from each set and mcb did not trip! Faulty fittings came to mind but 2 at same time seemed odd!

Replaced the lamps in the 2 fittings still connected and the lights came on. After several minutes they tripped so I thought maybe the cheap led GU10s were the cause.

I used my multimeter for supply at the lights instead. The problem I found was that either switch seemed to give a supply all 4 lights even though the switch wires cannot be connected as they are on separate twin and earth's from switch. I can't get my head around it!

Did a bit of testing with my multimeter and all the cables at each light appear to be in the correct terminals. I also testing it a few months ago and found no dead shorts or issues.

With the mcb off, I switched each switch individually and made sure that it was switching the 2 lights it should and not the other 2.iSo dead testing of the switches seemed like there was no interconnection between them and was switching correctly. But when circuit energised all the switch lives had voltage!

One thing I noticed when mcb off, I had 0.8v DC between the 2 switch lives at switch??

The only thing I didn't try was to physically disconnect the other 2 fittings, possibly faulty too?? back feed on neutral???

I am going back with my Meggar to test everything properly but I have recently done this and everything was fine. Just seems odd that the leds were burnt out and 2 fittings were causing the mcb to trip with no lamps in. Any ideas before I return would be much appreciated as I got to the point were I was thinking WTF!

All I can think is the other 2 fittings are faulty too and giving a back feed through the neutral but again doesn't sound possible with lamps removed and there are no electronic parts (only lamp holders)

Thanks

 

[telectrix]

wtf is a avt?

 

[telectrix]

Not much point in bringing them to the job , if they're going to lie down.

did your dad not teach you anything about the facts of life?

 

[Dave OCD]

...Which is where i am,next to the beach,in Hayle,Cornwall...got an AVT in me glove-box,too...like everyone else...:smartass:

I live about 10 miles from Hayle, weather's not great for a holiday at this time of the year though.

 

[sparksburnout]

AVT = average tart?

 

[sparksburnout]

No but how could that make 2 separate switch lives work from either switch?

If the worst comes to the worst, and all else fails, you could always get an electrician to come and have a look at the problem.

 

[Martin Kerr]

wtf is a avt?

Probably means an AVO , sure everyone's got one in the glove box.

 

[Geordie Spark]

If the worst comes to the worst, and all else fails, you could always get an electrician to come and have a look at the problem.

Finding one of those around here is like finding rocking horse .... manure. :001_9898: :sailor:

 

[PEG]

...well,it's a very common abbreviation,of a device the OP said he was short of...first letter;means "validated",second is the medium,scale or type of an electric characteristic,third is the description of the device role.

And,even on me hols,i always have one to hand:goofy:

 

[PEG]

I live about 10 miles from Hayle, weather's not great for a holiday at this time of the year though.

...Now that is a PROPER Cornish understatement!

Got family down this end,so regular visits are made...some Easters are sunbathing on the beach at St.Ives...others are spent chasing 47Kg LPG bottles around Gwithian Sands....but no problems launching the kids kites this year :lol:

 

[DPG]

...well,it's a very common abbreviation,of a device the OP said he was short of...first letter;means "validated",second is the medium,scale or type of an electric characteristic,third is the description of the device role.

And,even on me hols,i always have one to hand:goofy:

Don't know about anyone else, but I need another clue! Daz

 

[Pete999]

wtf is a avt?

More to the point wtfs a Meggar?

 

[telectrix]

a Bulgar is from Bulgaria, so a Meggar must me from Meggaria. think it's down in Dover.

 

[Noob2013]

UPDATE!

So I went back with my Meggar and found the issue!

Tested between the 2 switch lives at the switch and found a short (not picked up on my multimeter)

Started lifting floorboards to trace the cables and found a screw had just caught both switch lves in each t&e where they went through the joist!

These floorboards were lifted a week or so after I carried out the inspection and test!

The switch lives arcing together must be the cause of the LEDs burning out.

Sorted out the damage cables, tested and everything working bang on!

Appreciate all the advice and input given by everyone

 

[telectrix]

now that's a good result. i assume the cables were just notched into the joists with no mechanical protection. well done for perseverance, and thanks for letting us know the outcome. and welcome to the world of finding awkward faults. :sunny:

 

[Noob2013]

now that's a good result. i assume the cables were just notched into the joists with no mechanical protection. well done for perseverance, and thanks for letting us know the outcome. and welcome to the world of finding awkward faults. :sunny:

The cables were drilled through the joist (not low enough down though) but also the nails were pretty long.

It's always nice to have a fault and find it!