RCD tripping issue (again) - Earth Leakage?

[Milleniumaire]

Instant tripping won’t de detected by an Earth leakage test ……,

It doesn't always trip instantly, sometimes it takes a while, sometimes turning on something else in the house e.g. the garage lights, causes the trip.

The randomness of the tripping seems to indicate it is an earth leakage issue.

 

[Murdochcat]

You need continuity , then IR tests

Nothing else will help you

 

[ericmark]

putting 500V through the house wiring is not something I would want to do as I'm almost sure I will damage something and then I'm in a worse situation!

As said there is a 250 volt range.

If not tripping all the time, then clamp-on may help, but I went all RCBO, seemed a better option, as my consumer unit I need to go outside and down steps to get to.

 

[333rocky333]

"You’ve probably inadvertently connected lighting L-E or something similar"

Definitely not. I've checked this. On some of the SWA the earth is Grey and on other the earth is the usual yellow/green, so I'm 100% sure I didn't connect the wrong wires. Besides, the 2 new light fittings I originally added, which seemed to start this issue, have been removed. Even after removing some of the other circuits e.g. unplugging the festoon lights (C6) and/or disconnecting the wall lights (C5), the remaining lights will work but will eventually cause a trip, either after a length of time, or when a light etc. connected to the same RCD is turned on. I say "after a length of time", but it is possible someone switched something on!

you sure grey is the earth, convention these days is black earth and grey neutral however in the early days either way was often used
edit just see pics and some are different

 

[CountryFan]

There doesn't appear to be any pattern as to what causes the RCD to trip, except that the garden lights are on.

Have you checked for moisture ingress? Those wires that are loose in J3 - any connected to earth/cpc?

 

[Milleniumaire]

Have you checked for moisture ingress? Those wires that are loose in J3 - any connected to earth/cpc?

I can confirm the two lots of loose wires in J3 are from the two light fittings and they aren't currently connected up to the circuit (C1).

 

[ericmark]

If you have a neutral to earth fault, the turning items on/off often does not work.

As the load increases the resistance in the neutral wire means the voltage differential between neutral and earth also increases, which in turn means the current in any path between neutral and earth also increases.

Net result is, only way to find, is using a meter.

So the options are buying a meter and DIY, or get an electrician who has the meters.

 

[Milleniumaire]

you sure grey is the earth, convention these days is black earth and grey neutral however in the early days either way was often used
edit just see pics and some are different

I will open up all the junction boxes and double check, but I'm pretty sure the SWA that has grey, black and brown are the only ones in the garden as they are "extensions" of the original C1 circuit and were added when the underground junction boxes were moved above ground. Based on the photos I posted above for junction boxes J1, J2 and J3 on C1, the grey wires are consistently connected to earth.

You are correct in that the original wiring in the Garden wiring box is done in the way you say; black - earth and grey - neutral.

I could change the wires being used in junction boxes J1, J2 and J3 to be the same, but I'm 99% sure none of these particular wires go back to the Garden wiring box.

Thanks for pointing this out.

Edit: Looking at the photo of the Garden Wiring Box, circuit C1 is the third cable from the right. The SWA wires for this cable are coloured green/yellow, light blue and orange/brown so this particular SWA cable does not have a grey wire.

This SWA cable feeds the underground 3 way resin jointing box on C1. From this jointing box the same SWA (green/yellow, light blue and orange/brown) runs to J2 and I see in the image of J2 the same colour wires. Also from the underground jointing box is a short run of SWA which has wires grey, black and brown, feeding J1.

In J2, the green/yellow earth from the "supply" SWA is connected to the grey of the SWA that runs to J3 and in both J2 and J3 the grey is treated as earth.

So, while I take your point that ideally the grey should have been used as neutral, it is consistently being used as earth in J1, J2 and J3.

While I could change this in J2 and J3, it isn't possible to change it in J1, since the SWA feeding that junction box is connected to the buried resin jointing box, in which grey is connected to green/yellow.

 

[Milleniumaire]

If you have a neutral to earth fault, the turning items on/off often does not work.

As the load increases the resistance in the neutral wire means the voltage differential between neutral and earth also increases, which in turn means the current in any path between neutral and earth also increases.

Net result is, only way to find, is using a meter.

So the options are buying a meter and DIY, or get an electrician who has the meters.

Yes, I agree I am at this point.

I'm not experienced enough to further trouble shoot this issue myself and even if I was, I prefer the idea of the earth leakage clamp meter since it is "non invasive" and so much easier (and quicker) to use, as far as I can tell.

As much as I would like to understand what is going on and continue trouble shooting, I think I'm going to go down the route of having the consumer unit upgraded.

The garden lights and fountain pump have been a constant source of frustration over many years so maybe an upgrade and help from an electrician will sort it once and for all.

 

[ericmark]

All my garden sockets, are either plugged in, so easy and quick to disconnect if a fault is suspected, or on their own dedicated RCBO.