RCD tripping issue (again) - Earth Leakage?

[endecotp]

If it was an Earth to neutral “short” the RCD would trip immediately

Well “e-to-n fault” then.

A single LED light, or other load taking less than 35mA, can be connected between L and E without tripping its RCD.

I don’t think anyone else had picked up on the comment that it trips when something else in the house is turned on. Do we know how many RCDs there are, and whether these “other things in the house” are on the same or a different RCD?

 

[Murdochcat]

Well “e-to-n fault” then.

A single LED light, or other load taking less than 35mA, can be connected between L and E without tripping its RCD.

I don’t think anyone else had picked up on the comment that it trips when something else in the house is turned on. Do we know how many RCDs there are, and whether these “other things in the house” are on the same or a different RCD?

Quite so but a diyer won’t think of those points either

Cumulative leakage is a bigger issue these days, especially with single up front RCDs

 

[ericmark]

If it was an Earth to neutral “short” the RCD would trip immediately

I think we all know, not really referring to a dead short, but a low resistance connection, between earth and neutral, your comment is likely to confuse a non electrician.

 

[Milleniumaire]

Quite so but a diyer won’t think of those points either

Cumulative leakage is a bigger issue these days, especially with single up front RCDs

Not true in my case.

As a diyer, I am well aware that a number of MCB's are connected to the same RCD and I'm fairly sure I have stated that when lights or devices on any of the MCB's connected to the same RCD as the garden circuit, are turned on, this has caused a trip. Prime example is the garage lights.

Scenario:
I turn on the switch for the garden lights and they work. I go into the garage and turn on the lights and the RCD trips. The RCD covers the garage electrics and the garden lights.

Our consumer unit was installed in 2014. It is plastic (not that this makes a difference, apart from not being upto current regs, until someone decides plastic is better than metal) and is the dual RCD type. One of the RCD's protects 5 MCB's, including the garden lights, and the other RCD protects 6 MCB's.

One of the reasons I am keen to upgrade to a consumer unit using RCBO's, apart from the fact that 4 additional MCB's are affected every time the RCD trips, is that this "may" result in a lower earth leakage per RCBO, rather than the leakage being across 5 MCB's/1 RCD. I suspect this is wishful thinking and there will still be an issue to resolve on the garden circuit, but you never know!

 

[SUNRAY]

Well I'm confused.
Your drawing shows 8 cables in the main box, I see 7 - is that a me-issue? It is a bit scrappy but not unreasonable.
Currently I see cables linked as below:

I believe I see:
an incoming switched feed connected to a PUMP circuit (C4) highlighted in green.
an incoming switched feed connected to a WALL LIGHTS (C5)circuit highlighted in blue.
a BUSH circuit connected to nothing highlighted in black.
a TREE circuit connected to a 'PUM' circuit highlighted in orange.

If this is the case only the wall lights and the pump can work.

I think you are saying you have been working on C1 which appears to be disconnected currently.

I see 3 blacks sleeved green/yellow and 4 cables containing green/yellow wires. All earth wires are linked
I see 3 greys sleeved blue.

Where is the 'missing circuit' (I assume the socket)?

You say this box is the original work and all the other pics are of extended work. Which circuits contain the grey earth/black neutral and where are the extensions terminated any chance of a pic of that junction box?

Have you verified there are no E-N or E-L faults and what test kit do you have?


Sorry lots of questions some of which I assume you have answered some but there's already a lot out there to absorb. This is a big system to faultfind on remotely and I'll not be surprised if it doesn't get resolved on here.

 

[Collectors]

Have a check on any of the flexes as squirrels & rats love cable as its oil based & a protein. We had a few with this problem & yet we never found a dead one. Same with cables in the loft, they could strip back to the copper yet no dead ones.

 

[SUNRAY]

I once worked in a workshop with a 3ph supply (Not relevant) in a metal dist-board and had quite regular "false trips".
A couple of months in I had a slack day ...

I found 2 faults:
1) the Earth and Neutral bus bars were incorrectly used meaning the neutral was bonded to the enclosure. The installation was in steel trunking and conduit and at each socket the earth wiring was connected to the metal containment - creating multiple links between neutral and earth.

2) The most surprising lack of issue the ring final was connected via an add on RCD. However only one leg of the ring Line , the other leg was via a second MCB but a radial circuit connected in it's place.

There was a sequence of events when starting work to prevent the RCD tripping, it was a total fluke that the radial fed a redundant FCU and pretty much all of the load was within a short distance of the RCD but attempting to use a drill at the other end of the workshop it tripped everytime. Correcting the RCD wiring was the easy find and fix and made a big difference the incorrect busbar use was not so obvious as they looked so similar.

 

[mikehammer69]

Not true in my case.

As a diyer, I am well aware that a number of MCB's are connected to the same RCD and I'm fairly sure I have stated that when lights or devices on any of the MCB's connected to the same RCD as the garden circuit, are turned on, this has caused a trip. Prime example is the garage lights.

Scenario:
I turn on the switch for the garden lights and they work. I go into the garage and turn on the lights and the RCD trips. The RCD covers the garage electrics and the garden lights.

Our consumer unit was installed in 2014. It is plastic (not that this makes a difference, apart from not being upto current regs, until someone decides plastic is better than metal) and is the dual RCD type. One of the RCD's protects 5 MCB's, including the garden lights, and the other RCD protects 6 MCB's.

One of the reasons I am keen to upgrade to a consumer unit using RCBO's, apart from the fact that 4 additional MCB's are affected every time the RCD trips, is that this "may" result in a lower earth leakage per RCBO, rather than the leakage being across 5 MCB's/1 RCD. I suspect this is wishful thinking and thereA will still be an issue to resolve on the garden circuit, but you never know!

There will still likely be be a problem

 

[Milleniumaire]

Well I'm confused.
Your drawing shows 8 cables in the main box, I see 7 - is that a me-issue? It is a bit scrappy but not unreasonable.
Currently I see cables linked as below:View attachment 420655I believe I see:
an incoming switched feed connected to a PUMP circuit (C4) highlighted in green.
an incoming switched feed connected to a WALL LIGHTS (C5)circuit highlighted in blue.
a BUSH circuit connected to nothing highlighted in black.
a TREE circuit connected to a 'PUM' circuit highlighted in orange.

If this is the case only the wall lights and the pump can work.

I think you are saying you have been working on C1 which appears to be disconnected currently.

I see 3 blacks sleeved green/yellow and 4 cables containing green/yellow wires. All earth wires are linked
I see 3 greys sleeved blue.

Where is the 'missing circuit' (I assume the socket)?

You say this box is the original work and all the other pics are of extended work. Which circuits contain the grey earth/black neutral and where are the extensions terminated any chance of a pic of that junction box?

Have you verified there are no E-N or E-L faults and what test kit do you have?


Sorry lots of questions some of which I assume you have answered some but there's already a lot out there to absorb. This is a big system to faultfind on remotely and I'll not be surprised if it doesn't get resolved on here.

SUNRAY, thank you for getting into the detail of my garden electrics configuration. I agree, the circuit diagram has one more circuit than the photos are showing and I've now realised this is because the photos are a few years old and don't include the outdoor socket that was added in 2021. Here's a new photo I have just taken:

Garden Wiring Box New.jpg

• Milleniumaire
• Today at 8:38 PM

Here are the mappings of the circuits in my diagram to the garden wiring box.

In the garden wiring photo, as you say, there are 7 cables entering the box from the bottom, which are, from the left to the right:

a) From house switch 1 (pump on/off). SWA wires are coloured brown (L), black with earth sleave (E) and grey with blue sleave (N).
b) From house switch 2 (lights on/off). SWA wires are coloured brown (L), black with earth sleave (E) and grey with blue sleave (N).
the above are both labelled "MAIN X 2" in the box
c) PUMP LT- Circuit C2 - SWA wires are coloured brown (L), black with earth sleave (E) and grey with blue sleave (N).
d) PUMP - Circuit C4 - SWA wires are coloured orange (L), blue (N) and green/yellow (E).
e) TREE - Circuit C1 - SWA wires are coloured orange (L), blue (N) and green/yellow (E).
f) BUSH X 2 - Circuit C3 - SWA wires are coloured orange (L), blue (N) and green/yellow (E).
g) WALL LTS - Circuit C5 - cables wires are coloured brown (L), blue (N) and green/yellow (E).
h) Rightmost SWA cable - Circuit C6 (outdoor socket). SWA wires are coloured brown (L), black with earth sleave (E) and grey with blue tape (N).

As you say there are two incoming SWA cables at the left, labelled MAIN X 2. Both these cables come from a double switch in the house, so each cable is connected to one of the switches, allowing separate control of the garden water feature pump and all the garden lights.

The top (white) terminal connector shown in the wiring box are for the pump (C4) and the lower, slightly larger terminal connector is for all the lights except the festoon lights (C6), which are plugged into an outside socket fixed to the right side of the wiring box.

I apologise as the photo shows some of the lighting connections have been removed in order to test certain circuits. Normally all the lighting circuit cables would be connected to the live and neutral terminals in the centre of the wiring box. In the new photo I've just added, the BUSH x 2 (C3) and WALL LTS (C5) are currently disconnected.

 

[Milleniumaire]

You say this box is the original work and all the other pics are of extended work. Which circuits contain the grey earth/black neutral and where are the extensions terminated any chance of a pic of that junction box?

The following junction boxes contain SWA wires that are black, brown and grey: J1, J2, J3. These are all on C1. I have already provided photos of these. The pump (C

All the original underground connections were moved above ground into junctions boxes J1, J2, J4, J6, J7 and J8. Junction boxes J3 and J5 were added later, hence the use of resin connection boxes to add these to the relevant circuits.

I will attempt to take photos of the inside of the remaining junction boxes tomorrow just to give a full picture.

Have you verified there are no E-N or E-L faults and what test kit do you have?

I haven't got any test kits. All I have done is try to isolate individual garden circuits in an attempt to determine if any one circuit is causing the issue. This has failed, since the RCD tripping is currently happening regardless of which circuits are connected, so there appears to be no pattern to identify a particular part of the garden system that is causing the issue.

I'm therefore at the point where I need to engage an electrician with the relevant testing equipment so they can try to identify the problem. However, a few years ago, the last time I hired an electrician to look at this wiring, he spent around 4 hours working his way around all the fittings and didn't isolate where the issue was, simply telling me there was dirt inside the wall lights and it needed to be cleaned out!

The festoon lights are a constant issue and despite being "outdoor" quality, the bulbs regularly fail, either due to water ingress of just dimming light! We've probably spent as much on new bulbs than on the original cost of the lighting! On one occasion, when they constantly caused the RCD to trip despite replacing faulty bulbs, replacing the 3rd length (there are 3 daisy chained together) fixed the issue!