Three-fault Friday

Not as fun as sloppy-seconds Saturday but that’s another video entirely. Instead, we have Friday fault finding faff following friggin’ fitter’s fishy fittings flippin’ flooding!
Yes, I give you not one fault, not even two, but three (count ‘em!) and all at the same site! We were called after a duff drainpipe drenched the foyer and basement bathroom.
See pinned comment for erratum!
One: RCD fuse unit seized.
Two: An aged breaker more sensitive than a left-wing metrosexual carrying an iPad in a rainbow-coloured man-bag to deliver a diversity training course at the BBC.
Three: Bathroom lights that pop as you plonk your buttocks onto the windowless basement bog.
Energising known bad wiring isn't ideal, a point laboured in the ending, but it’s important to verify a fault condition before undertaking remedial work so you can confirm what’s reported is accurate and you know you’re making a difference when wielding the tools. Once verified, we get the tester onto it and pull out some numbers. Is there resistance to earth? Does it pass an IR test to earth? If it’s a line/neutral fault, what’s the resistance between those cores before we remove loads?
With the baseline data, we hopefully know what kind of fault we’re looking for and perhaps where to start looking. Here, the location was given away by an audible report in the bathroom. We'd been told it was the lights at fault as they had been seen wet, but the downlight holes merely provided an escape for the sound.
Usually a faulty circuit doesn’t give a clue as to quite where the failure is, so we figure out the likely halfway point, disconnect it and see which half the fault is on. Repeat until it’s cornered. Here, there were no points to break it down as all rooms had downlights caulked to the ceiling, their removal risking damage to finishes and, as we found, even extracting them didn’t guarantee access to any logical junction arrangement.
The JB we found in the bathroom served the fan and lights. The CPCs were presumably disconnected because the downlights were originally 12V MR16s. At some point the transformer(s) had been binned for a GU10 conversion leaving cabes & accessories on 230V. The faulty cable was tee'd off before that junction from somewhere we haven’t seen. It looks like that cable provided a non-fused non-isolated L-N-PE to the fan point, albeit disconnected and hiding in the wall. Maybe it had been there since the bathroom was fitted 20 years ago? It wasn’t visible until we wanged a hole in the fan liner, so it appeared the fan had just one cable going back to the JB. We had no way of knowing there was another cable there until the liner was opened.
We only had two ends of the circuit to work with - the CU reporting a fault downstream & the JB in the bathroom with a fault upstream. There were no other junctions to find without smashing out walls/ceilings. It was fortunate that visual and audible cues were present. Had that cable been obscured, we’d have nothing to go on.
This is a rare example of dead testing can only getting us so far as there wasn’t enough of the circuit accessible to work with.
The damage could have been worse: Four 20mm holes in the ceiling for the camera; the fourth hole betraying the location of a JB in the wall. A section of wall was cut for access. Finally, the fan liner had a chunk taken out of it and a hole was opened in the tiled wall for us to gain access.
One may argue we were wrong to re-energise even with the fault found, after all there are cables without CPCs, a live cable above the bath in a gel box, a JB still in the wall and non-fire rated downlights. Well, we’re not here to cure all the ills of others and we’ve only so much time booked to a job and limited permission from the client on what they'll put up with. Our brief is to find the fault & get the lights back on. That we did. We found a load of other cack requiring rewiring/repair/replacement, but all we can do is inform the client and urge them to book us, or any reputable spark, to put right. We can't force them to do so. Some may say it's better to leave the circuit disconnected, but the homeowner was pulling a floor lamp into the bathroom off a non-RCD socket so they didn’t have to bathe and crap in darkness. What’s safer, getting the lights on, even with their problems, or leaving the client with a trailing cable trip hazard, operating a Class I floor lamp potentially with wet hands? If we refused to restore lighting, they would have found someone else who could.
Is the place safer now than before we turned up?
Yes. It is.
We advised the client of what's needed, but there are no more C1 conditions and it’s up to them whether they go to the effort and expense of paying heed.
The Metrel MI3152 is on loan in a deal where we get to play with something shiny we can’t afford, & Metrel get their wares shown to the five subscribers I have here on this channel. Then we hand it back to ‘em slightly worse for wear. Everyone’s a winner. Sort of.