How time flies! Back in August 2019 I was having issues with the garden lights causing an RCD to trip as discussed in the following post:
Strange RCD tripping issue
I did eventually resolve this but it required an electrician to work through the fittings to try to identify the issue. He didn't seem to have the correct equipment i.e. I didn't see him do any earth leakage testing, but he spent a lot of time disconnecting each light fitting and reconnecting it. He pointed out that some of the flush fitting wall lights, which are clipped into an enclosure that is buried into the wall, was full of gung i.e. dirt, dead insects etc. all of which probably got in through the cable entry point in the back of the enclosure. I therefore cleaned them all out. I can't remember if this fixed the issue at the time, but over the years I've continued to have problems with these garden lights causing the RCD to trip and I've done various things to try to resolve them, including:
1. Replacing all the underground galvanised steel junction boxes that were installed by the original electrician (in 2017) to connect SWA cables to light fittings. These were filled with gell. The connections for light fittings were moved above ground and junctions boxes used and any remaining underground SWA connections were done using resin filled jointing kits.
2. Replacing parts of the festoon lights (3 lengths connected together).
3. Keeping the inside of the wall lights connection box clean.
4. Ensuring the festoon string bulbs are replaced when they fail, which seems to be far too often!
All of this seems to have ensured the RCD hasn't tripped, until now!!
A couple of weeks ago I added a couple of new garden lights, both wired into the same above ground junction box at the end of an existing SWA cable run. As soon as I turned the garden lights on, the RCD tripped. I disconnected both new lights, turned the garden lights on and to my surprise it still tripped! I've now been unable to resolve this despite playing around with the lights and disconnecting (live and neutral) various connections in the outside garden junction box. On the odd occasion where the lights stayed on for any length of time, they would eventually trip or turning on another appliance or switch protected by the same RCD would cause them to trip. When the mcb for the garden lights is off, there are no issues.
This therefore looks like an earth leakage problem, but I have no idea why it should have started when the two new light fittings were attached or why it has continued after they have been removed!
I have checked every junction box and every wall light and there is no sign of damp in any of them. There are two underground resin junction kits, but I find it hard to believe they are suddenly causing an issue.
Here's a diagram I produced showing the layout of the various garden light fittings and garden water feature pump. 1.5mm twin and earth SWA is used for most cable runs, except the wall lights as the external waterproof cable was run directly behind the wall and filled with rubble, before soil was added. All connections to lights and the pump are done above ground in a junction box, using SWA glands and earthing nuts.
I suspect I will need to engage an electrician, but would appreciate your thoughts on what else I might do to try to identify the problem.
Strange RCD tripping issue
I did eventually resolve this but it required an electrician to work through the fittings to try to identify the issue. He didn't seem to have the correct equipment i.e. I didn't see him do any earth leakage testing, but he spent a lot of time disconnecting each light fitting and reconnecting it. He pointed out that some of the flush fitting wall lights, which are clipped into an enclosure that is buried into the wall, was full of gung i.e. dirt, dead insects etc. all of which probably got in through the cable entry point in the back of the enclosure. I therefore cleaned them all out. I can't remember if this fixed the issue at the time, but over the years I've continued to have problems with these garden lights causing the RCD to trip and I've done various things to try to resolve them, including:
1. Replacing all the underground galvanised steel junction boxes that were installed by the original electrician (in 2017) to connect SWA cables to light fittings. These were filled with gell. The connections for light fittings were moved above ground and junctions boxes used and any remaining underground SWA connections were done using resin filled jointing kits.
2. Replacing parts of the festoon lights (3 lengths connected together).
3. Keeping the inside of the wall lights connection box clean.
4. Ensuring the festoon string bulbs are replaced when they fail, which seems to be far too often!
All of this seems to have ensured the RCD hasn't tripped, until now!!
A couple of weeks ago I added a couple of new garden lights, both wired into the same above ground junction box at the end of an existing SWA cable run. As soon as I turned the garden lights on, the RCD tripped. I disconnected both new lights, turned the garden lights on and to my surprise it still tripped! I've now been unable to resolve this despite playing around with the lights and disconnecting (live and neutral) various connections in the outside garden junction box. On the odd occasion where the lights stayed on for any length of time, they would eventually trip or turning on another appliance or switch protected by the same RCD would cause them to trip. When the mcb for the garden lights is off, there are no issues.
This therefore looks like an earth leakage problem, but I have no idea why it should have started when the two new light fittings were attached or why it has continued after they have been removed!
I have checked every junction box and every wall light and there is no sign of damp in any of them. There are two underground resin junction kits, but I find it hard to believe they are suddenly causing an issue.
Here's a diagram I produced showing the layout of the various garden light fittings and garden water feature pump. 1.5mm twin and earth SWA is used for most cable runs, except the wall lights as the external waterproof cable was run directly behind the wall and filled with rubble, before soil was added. All connections to lights and the pump are done above ground in a junction box, using SWA glands and earthing nuts.
I suspect I will need to engage an electrician, but would appreciate your thoughts on what else I might do to try to identify the problem.
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