Went to an infant school for power tripping out in a classroom, turned out to be a portacabin block with RCD main switch board, moved all sorts of clutter and took the boxing in off so I could get board cover off *roll eyes*. Quick global insualtion test with L&N linked on the whole board, very low, 0.1* ish. Ok break it down, turned out to be a newish looking 2.5 twin dobbed in with something else on a 16A. Test rest of board, fine so needed to find out what this supply fed as it wasn't marked
Traced where cable seemed to be going, heading towards the toilets, find with voltstick that saniflow spur is now dead. Test at spur, same reading, so thats the issue, was about to disconnect the saniflow, put everything back together and pass it back for a plumber to attend to swap the thing out, when I tested the thing in isolation and it was fine. I think at first I convinced myself I'd fallen into the trap of the fault being to true earth and the test to CPC, but verified that wasn't the case. It was then I noted yellow liquid in the back of the back box. The spur was badly positioned just behind the toilet and the little darlings had been missing and pissing on the spur. I changed the spur like for like now, explained the issue to the class teacher (who was a little mortified) I said we could change it out to a weather proof one (I didn't have one on van at the time) but perhaps they should look at house training the kids first. They did want it changed, so I put on my job card that it requires a visit to fit an "I-PEE rated spur", I don't think my colleague he went back found it that funny tbh (But fairs fair, he had been out the week before, reset the RCD and decided it was all fine as he didn't want to try and make space to get in the DB)