H
Herisson
I'd be very grateful if someone can help with this.....
I've added a diagram to help explain. This is single cabling not a ring (I'm in France). All the cabling is underground which is split into 3 at a junction box by MCB's. There are 5 spurs above ground on the cable in question and each has it's own RCBO.
I have an RCD (Type A) on the distribution board (RCD 1) which intermitently trips. Sometimes it takes an hour sometimes 24 hours, rarely shorter or longer. I was actually standing at the board by chance on one occasion when it tripped and it refused to go back on again despite several attempts, after a few miutes it went back on ok and stayed on for a few hours.
Using the MCB's I isolated the problem to the cable in the diagram. Having switched off all the RCBO's at each spur the tripping continued.
To try and isolate the problem further I disconnected the cable at each spur working backwards from spur 5 until the tripping stopped. This occurred after diconnecting the cable running to spurs 4 & 5 at spur 3.
To allow the continued use of the system up to and including spur 3 (and the other 2 MCB circuits) I installed an RCD (let's call this RCD 2) on the cable from spur 3. With this switched off there were no trips. Once switched on RCD 1 started tripping again.
Other than one RCD being more sensitive than another the reason for this is beyong my knowledge, so I interchanged RCD 1 and RCD 2. The trips were then on RCD 2 at the distribution board.
The installation has been untouched for 2 years and the connections at the spurs are secure. No power is being consumed during all this and no appliances are connected.
So my questions are:
I've added a diagram to help explain. This is single cabling not a ring (I'm in France). All the cabling is underground which is split into 3 at a junction box by MCB's. There are 5 spurs above ground on the cable in question and each has it's own RCBO.
I have an RCD (Type A) on the distribution board (RCD 1) which intermitently trips. Sometimes it takes an hour sometimes 24 hours, rarely shorter or longer. I was actually standing at the board by chance on one occasion when it tripped and it refused to go back on again despite several attempts, after a few miutes it went back on ok and stayed on for a few hours.
Using the MCB's I isolated the problem to the cable in the diagram. Having switched off all the RCBO's at each spur the tripping continued.
To try and isolate the problem further I disconnected the cable at each spur working backwards from spur 5 until the tripping stopped. This occurred after diconnecting the cable running to spurs 4 & 5 at spur 3.
To allow the continued use of the system up to and including spur 3 (and the other 2 MCB circuits) I installed an RCD (let's call this RCD 2) on the cable from spur 3. With this switched off there were no trips. Once switched on RCD 1 started tripping again.
Other than one RCD being more sensitive than another the reason for this is beyong my knowledge, so I interchanged RCD 1 and RCD 2. The trips were then on RCD 2 at the distribution board.
The installation has been untouched for 2 years and the connections at the spurs are secure. No power is being consumed during all this and no appliances are connected.
So my questions are:
- Does this mean there is a problem with the underground cabling between spurs 3 and 5 and if so, how can it take so long to trip?
- When I interchange RCD's 1 and 2 and the problem is beyond spur 3 why does only the RCD on the distribution board trip and not the one nearer the problem?