Downlighters tripping RCD

[CraigL43]

Hopefully some of you more experienced people can assist. One lighting Cct with 12 Downlighters off the same RCD functioned well for 5 years. Cct now trips when power applied, It was after about circa 5 minutes before it tripped. Now it is off without any reset.
What i did do.... I have isolated each lamp out of the Cct (G10), and tried to understand which position was causing the CCt to trip. No joy....... Changed each lamp and also left disconnected to try and remove the lamp from being the problem. I thought maybe defective RCD, but i don't think so..... Possible rodent problem in the ceiling..........Don't want to get seduced by this this as taking the ceiling down will be problematic. Any Advice appreciated!!

 

[ImpededLoop]

If the RCD is tripping it'll be a fault to earth (cpc). The time delay could indicate moisture. Is there an outside light on the circuit? Removing the lamps won't rectify an earth leakage fault.

 

[littlespark]

The supply cables should be accessible from the hole that the down light fits in. There should be a joint box between the lamp holder tails and the fixed wiring.

From there, you can disconnect legs to separate the down light string and go along from the first one, get it working, then connect the second. Eventually you’ll find which one is causing the trip.

Be aware that rcds trip with a neutral-earth fault as well as live- earth

 

[brianmoooore]

IF the RCD shares this lighting circuit with other circuits, the fault may be an earth to neutral one on any of the other circuits, with the tripping caused by the normal inrush of 12 lamps.
IR tester needed, along with someone with enough experience to interpret its results.