Hi,
Our house had completely new wiring installed about 1.5 years ago. This morning (and I guess it happened when a light switch was turned on somewhere) one of the RCDs in the CU tripped.
After switching off all MCBs on this side of the RCD, resetting the RCD itself then switching each MCB back on, I've isolated the problem to one of our downstairs lighting rings.
On this ring, there are 15 regular CFL downlighters, 4 water resistant ones (bathroom), 1 bathroom mirror (also florescent, but with heating pad) and - unknown to me up to this point (qualified spark fitted the new system) - two lights that sit outside our front door (25w halogen). MCB is 6A.
As soon as I switch the MCB for this ring on, it trips the RCD (the MCB remains un-tripped) - it doesn't matter if all of the load is switched off (note that I can't switch the heating pad of the mirror off, and therefore even with all switches off there is a small load).
The obvious thing for me was the outdoor lights suffering from water ingress due to the rain last night - though we have disconnected the live from their indoor switch and still get the trip.
Does this sound like a dodgy MCB (note again that the MCB doesn't trip, only the RCD if that MCB is switched on - is that expected?) or is it still possible that the outside lights are causing a problem, even with the live disconnected from the switch?
So far we have disconnected all of the hallway lights (5 CFLs) and the bathroom (4 water resistant CFLs) as well as disconnecting the outdoor light's live. Still tripping.
Another note - if the circuit is left for a while then switched in again, the trip takes 10 seconds to happen - then after resetting, will trip instantly again (so magnetic trip vs thermal trip - does this give any clues?).
Final note - we've not had a single trip in this house for the entire 1.5 years. 3 weeks ago, a utility company came and replaced our old style main fuse bulkhead (metal type) with a plastic one (inc. digging up the driveway to connect). After that, the electricity company came and changed the meter. Since then we've had a single trip in the kitchen (which was fine after a reset), plus this new trip. Is it possible they changed the type of earthing during this process and something has gone weird?
Thanks in advance for any help!
Edward.
Our house had completely new wiring installed about 1.5 years ago. This morning (and I guess it happened when a light switch was turned on somewhere) one of the RCDs in the CU tripped.
After switching off all MCBs on this side of the RCD, resetting the RCD itself then switching each MCB back on, I've isolated the problem to one of our downstairs lighting rings.
On this ring, there are 15 regular CFL downlighters, 4 water resistant ones (bathroom), 1 bathroom mirror (also florescent, but with heating pad) and - unknown to me up to this point (qualified spark fitted the new system) - two lights that sit outside our front door (25w halogen). MCB is 6A.
As soon as I switch the MCB for this ring on, it trips the RCD (the MCB remains un-tripped) - it doesn't matter if all of the load is switched off (note that I can't switch the heating pad of the mirror off, and therefore even with all switches off there is a small load).
The obvious thing for me was the outdoor lights suffering from water ingress due to the rain last night - though we have disconnected the live from their indoor switch and still get the trip.
Does this sound like a dodgy MCB (note again that the MCB doesn't trip, only the RCD if that MCB is switched on - is that expected?) or is it still possible that the outside lights are causing a problem, even with the live disconnected from the switch?
So far we have disconnected all of the hallway lights (5 CFLs) and the bathroom (4 water resistant CFLs) as well as disconnecting the outdoor light's live. Still tripping.
Another note - if the circuit is left for a while then switched in again, the trip takes 10 seconds to happen - then after resetting, will trip instantly again (so magnetic trip vs thermal trip - does this give any clues?).
Final note - we've not had a single trip in this house for the entire 1.5 years. 3 weeks ago, a utility company came and replaced our old style main fuse bulkhead (metal type) with a plastic one (inc. digging up the driveway to connect). After that, the electricity company came and changed the meter. Since then we've had a single trip in the kitchen (which was fine after a reset), plus this new trip. Is it possible they changed the type of earthing during this process and something has gone weird?
Thanks in advance for any help!
Edward.