Pandora's Box Fault Finding

[johnnyuk]

Hi all

I don't appear to be able to post in the DIY forum so apologies if this is the wrong place.

I live in a block of flats with an external CU for the external (and some internal) circuits, which are 90% lighting with a couple of sockets here and there.

The RCBOs keep tripping on three of the circuits and when they trip they tend to trip other RCBOs at the same time. Before I get an electrician round I want to do a bit of circuit mapping and basic fault finding to make their life a bit easier. Predictably:

• no circuit diagrams
• what is written on the CU is a mess and doesn't seem to bear any relation to what is actually on each circuit
• mods have been made by residents to various circuits who clearly did not have the necessary knowledge
• there's also a bar heater and a water heater on the circuit which live in a shed externally
• there's clearly water ingress to a number of badly fitted external lights which have perished gaskets and missing fixing screws

Before I start I wanted to post a picture of the CU just to get any kneejerk comments from the forum - it seems to be a mix of RCBOs and MCBs which I've not seen before. The three circuits that are tripping are marked but I will see what they trip when I start investigating. One trips immediately, the other two after a few seconds.

I'm a keen amateur but not qualified so do have my own megger, budget clamp meter and a lot of experience in construction.

Any initial thoughts on the attached image before I start doing basic investigations? Will start by mapping out the circuits, then inspecting the external lights for obvious faults, then probably get the megger out.

 

[Mike Johnson]

First thoughts are I can't see any test buttons on those RCBO's are they covered by your labels, but the most glaring fault is the external sockets off a MCB, dangerous and not in regulation, unless that MCB is powered off one of the RCBO's.

The most common tripping fault is water ingress into external lights/sockets, I would strongly advise getting an electrician in.

 

[johnnyuk]

Thanks Mike yes the test buttons are covered by the labels - updated image attached. The RCBOs I believe are Lewden 16/30/SP

Just done a quick check and like I say the labelling is a joke. The external socket is actually on the RCBO-protected circuit labeled "Garage Lights R1H".

 

[johnnyuk]

Let me do a bit more investigation and I'll see if there is a clearer question I can ask the forum.