intermitent tripper

[mr leffe]

i have an intermittent problem with my lighting circuit. the mcb trips intermitently not always with the same switch but most often in the living room where there are 15 20w halogen lights. There are also a further 21 20w halogens through out the flat plus 4 ordinary lights and 2 extractor fans on the same circuit. the mcb has even tripped when nothing has been on. the mcb also buzzes occasionally. i have tried some very basic fault finding removing lamps in turn, trying another mcb, isolating the extractors and checking switchs for any shorts all to no avail. i have had no problems with the lighting for 3 years since the halogens were installed and nothing has been added to the circuit.
please help

 

[Damocles]

Are you quite sure that upstairs are not getting their electricity supply off your lighting circuit? Something else loading the circuit quite heavily could explain what is happening. This is not a joke, such things have been done.

If you have really changed the mcb and this is still happening, then it is difficult to see what can be going on which would explain it tripping with nothing turned on. Is there a socket connected to the lighting circuit intended for a lamp but with the fridge plugged in?

It might just be possible to try switching off all other mcb, turn off everything you know about on the lighting circuit and check to see if the electricity meter still moves.

 

[mr leffe]

thanks for the tips i will check that out. in the mean time i seem to have solved the problem by replacing the mcb with the original old school wire style cartridge. any idea why this seems to have solved the problem?

 

[plugwash]

first there is the question of what is inside that rewirable

just because it *says* 5A doesn't mean it is loaded with 5A fusewire

also there are some patterns (very brief shorts like those from blowing lamps being one) which will take out a mcb but not almost any type of fuse

 

[ban-all-sheds]

Why go back to a fuse? Surely it would have been better to put a bigger MCB in, say 40A?

If your MCB was tripping under circumstances other than when bulbs blew, then curing it by replacing the protective device with one which does not activate is an appallingly bad idea....

 

[mr leffe]

the cartridge fuse has 5A fuse wire.
surly replacing a 5A fuse with a 40A fuse is the more appaling idea?

nearly as bad as pony little truisms

 

[Damocles]

Your original comment about buzzing might suggest the mcb is working hard, or something funy is happening to the load on it. Assuming we can now dismiss the neighbours, the fault must be something still connected.

You have got a lot of halogens, which sometimes have a bad reputation for causing tripping. 12V halogens have transformers, so conceivably one has developed a fault. Is there any pattern to which lights are on when a trip occurs. If all the halogens are the same, maybe more than one transformer has the same problem?

Except you say the mcb trips when nothing is turned on. This seems very unlikely, could it have tripped when something was switched on or off?

 

[ban-all-sheds]

the cartridge fuse has 5A fuse wire.
surly replacing a 5A fuse with a 40A fuse is the more appaling idea?

'twas meant to be sarcastic....