MCB Keep tripping

[naz786]

Hi everyone

I went to have looka job where the lighting MCB keep tripping after few mins,

Its 3 story house with only 1 lighting circuit. i had look around every thing seems to be ok and changed mcb still tripping, There is a second floor bathroom where they had a leak about 3 weeks ago. but mcb only started tripping 2days ago.

by the way its Split load CU

Any idea or help would be much appreciated

Naz

 

[SPECIAL LOCATION]

Hi everyoneI went to have looka job where the lighting MCB keep tripping after few mins,

Its 3 story house with only 1 lighting circuit. i had look around every thing seems to be ok and changed mcb still tripping, There is a second floor bathroom where they had a leak about 3 weeks ago. but mcb only started tripping 2days ago.

Any idea or help would be much appreciated

Naz

What is Everything?

what actual bits about this everything are ok..

and how do you judge OK..

3 story house.. only one light circuit???

How many lights are actually ON the circuit..

possible max wattage? (thus current)

Have you just "Looked" or actually tested anything?

What's your Insulation resistance test results..

Distinct lack of "electrical info here to go on"

so could be anything TBH...

Dodgy cable..

Dodgy fitting..

Dodgy junction box..

need more meat on the bones to chew over.

we are ruddy good on this forum...

But don't think any of us have got to the level a time-space-continuum-mind-readers..

able to see into a fault at a remote property!

Damp can take a while to ingress into something...

how do you know there is still no leak..

WHY did you change the MCB?

that would have been the last thing on my list..

MCB is most likely doing exactly what it has been designed to do IMHO!

:| :C

 

[naz786]

Hi SPECIAL LOCATION

I only had quick look, Mcb trips even if all the ligths are off.

They said they have had this problem before, then it stopped

there are about 14 lights on the circuit + 3 downlights.. Im going back there Monday to carry out testing. Will do IR test on monday.

Any pointer would be great help

ty

naz

 

[SPECIAL LOCATION]

Hi SPECIAL LOCATION I only had quick look, Mcb trips even if all the ligths are off.

They said they have had this problem before, then it stopped

there are about 14 lights on the circuit + 3 downlights.. Im going back there Monday to carry out testing. Will do IR test on monday.

Any pointer would be great help

ty

naz

Trips with NO loads on....

Got to be some current flowing somewhere for it to trip?

Sounds like a defect on some part of the permanent live conductor of the circuit..

either down to earth or neutral... (is there an RCD on the circuit?)

Check for any squashed or trapped live conductors...

e.g. back of a switch box

behind light fittings etc..

I would expect your insulation resistance will show low between 'L' and either 'N' and/or 'E'

:C

 

[naz786]

No RCD as its split load cu.

It trips with no load on as you said, would this have somethign to do with the leaks they've had recently.

Thank you very much for your help mate

ty

Naz

 

[sparkytim]

Could well do, its always good to get some "history" of whats been going on.

Learnt my lesson to always ask first anything "unusual happened" before you launch in. I had a call out one bank holiday to loss of supply on Ring main and after pinning it down to fault between two sockets AND lifting floor boards above, proved fault in cable going down wall close to Warm air circulation vent, "Oh I just re drilled the fixing for that this Morning, wonderded why the drill stopped"

Customers don't you just love em!

HOWEVER you also can get Red herrings so just go about things in a logical way, have a good look FIRST for anything obvious AND then Isolate at supply end and Test, break down circuit to prove whats ok and whats not.

 

[naz786]

Thank you sparkytim

 

[Lurch]

Learnt my lesson to always ask first anything "unusual happened" before you launch in.

First thing to ask. 99% of faults are user induced or they will have that key bit of information whether they know it or not.

 

[batty]

Might be an idea to split circuit up when its fixed would be a bum if the lights trip when you are upstairs if the cu is on the bottom floor and the torch is on the bottom floor.

 

[steptoe]

Hi SPECIAL LOCATION I only had quick look, Mcb trips even if all the ligths are off.

They said they have had this problem before, then it stopped

there are about 14 lights on the circuit + 3 downlights.. Im going back there Monday to carry out testing. Will do IR test on monday.

Any pointer would be great help

ty

naz

after client error and actions that should be FIRST test to carry out, anything else is a pure waste of everyones time.

including mine for reading this when you havent even carried out the most basic of tests.

 

[naz786]

Thanks every one, going back there tomorrow morning will post back what i find.

many many thanks for your advice and help

Naz

 

[Andy™]

Hi everyoneI went to have looka job where the lighting MCB keep tripping after few mins,

Its 3 story house with only 1 lighting circuit. i had look around every thing seems to be ok and changed mcb still tripping, There is a second floor bathroom where they had a leak about 3 weeks ago. but mcb only started tripping 2days ago.

by the way its Split load CU

Any idea or help would be much appreciated

Naz

so, you get called to fault find, and your first thought is 'better change that MCB rather than IR test the circuit'

then your next thought is to go post your problem on a forum instead of any basic testing?

maybe you were not thorough enough changing the MCB. i would sugget replacing the CU