What is the hardest fault you have ever had to find?

[Top Cat]

Thought i would start with one i had 30 years ago!

Office block, loads of fluorescent's etc all the ground floor not working, rewireable fuse.

Fuse wire disintegrated so fault not overload.

Meggered everything, clear L-E, N-E. but picking up control gear for L-N.

Thought i would try just putting new fuse wire in! Tried it and everything worked OK.

Three weeks later same call.

Thought i better do it properly this time so took down all flo's, checked gear inside, disconnected gear. Meggered again, no fault apart from L-N.

Checked with staff to see if any other rooms. Oh yes , a store cupboard.

Found an enclosed light fitting with 100 W lamp in it. It was the sort with the aluminium "pie dish" reflector. I found that it had chock block connectors behind it that had half melted to the earthed pie dish.

Turns out they hardly use the store cupboard and if someone left light on for more than 15 minuets the chock block would get hot, melt against pie dish and blow fuse, then as it cooled the plastic would retract and hey presto no fault!

 

[mark ju]

This was years ago, back when we first started fitting RCD's to domestic properties, mid 80's?

A couple had recently moved into a newbuild property and after a couple of weeks the rcd started tripping. Always evening time. It would reset then trip 20/30 minutes later. They ended up the first night sitting there with no power (lights were fine) until morning.
We turned up for work and i kid you not, three of us stripped that house apart, changed the rcd and generally went round in circles. Could not find any problem at all...then it happened that night, and the next. Even had the boss in with us, checked everything again, no problem. On the forth morning when we got there it transpired that it had tripped again. So me and a mate decided to stay on after work and see what happened. We were there when the RCD tripped, and upon meggering the suspect ring, the fault was slowly clearing but it became apparent it was somehow related to the central heating being on. Reset the RCD and when it tripped again, we were in there quick. Turned out that in the utility room which was one of those type on the side of the house in line with the garage, the two three cores from the programmer were run behind the truss and they were crossed over. As the boiler heated up, the truss twisted slightly and pinched one of the three cores. As it cooled it released it and the fault disappeared! Two minutes in the small loft area and uncrossing the cables, problem solved. That was a right b*****d to find, must have spent altogether twice as long looking for that fault as it took to do the install.

 

[Guest111]

worked on a nursing home and the outside lights (bollards) kept tripping out went up there quite a few times and tested but couldnt find the fault as the staff were not allowed to call me in and if it happened at weekend it would be monday when I was told about it.Finally I left instructions that I was to be called as soon as it tripped even if it was late at night,as it was now getting silly when they rang I went out and it had rained so tested IR and it was low to both neutral and earth from live.Went back the following day to check everything and several hours later found 3 armoured cables joined with push fit connectors in a piece of waste pipe filled with a blue jelly wrapped in tape and buried.found this was the previous sparks preferred method for U G joints in cables.

 

[Farmelectrics]

hope you hit them for a call out lol

 

[Wiredspark]

Hardest fault to find?????

Trying to find a fault with the misses cooking when I had come home late on a Friday and had my heart set on a Chinese for dinner.

 

[ipf]

This was years ago, back when we first started fitting RCD's to domestic properties, mid 80's?

A couple had recently moved into a newbuild property and after a couple of weeks the rcd started tripping. Always evening time. It would reset then trip 20/30 minutes later. They ended up the first night sitting there with no power (lights were fine) until morning.
We turned up for work and i kid you not, three of us stripped that house apart, changed the rcd and generally went round in circles. Could not find any problem at all...then it happened that night, and the next. Even had the boss in with us, checked everything again, no problem. On the forth morning when we got there it transpired that it had tripped again. So me and a mate decided to stay on after work and see what happened. We were there when the RCD tripped, and upon meggering the suspect ring, the fault was slowly clearing but it became apparent it was somehow related to the central heating being on. Reset the RCD and when it tripped again, we were in there quick. Turned out that in the utility room which was one of those type on the side of the house in line with the garage, the two three cores from the programmer were run behind the truss and they were crossed over. As the boiler heated up, the truss twisted slightly and pinched one of the three cores. As it cooled it released it and the fault disappeared! Two minutes in the small loft area and uncrossing the cables, problem solved. That was a right b*****d to find, must have spent altogether twice as long looking for that fault as it took to do the install.

Lesson learned.........Don't get your wires crossed ?

 

[mogga]

"hardest" wasnt "hard" in the end working with the cooncil
wonans RCD was tripping every day at lunchtime when she used her kettle
tested everything ,all OK
Tested her kettle before and after boiling all OK
2 days later gaffer told us to go over in the morning and follow her routine
she got up had a coffee,made a coffee for her bedridden hubby,made him another coffee before work
made him a flask for during the day
when she got in made herself a coffee made him a coffee n it tripped
checked everything and the spout of ketle was pointed under wall units causing abuild up of steam hence tripping rcd
By time we got there originaly steam had dries up n all clear
turned kettle 45% problem sorted

 

[the pict]

Not a fault as such more errors on the part of people with half a brain, someone chopped a ring and fed it up into the attic where they were GOING to put a extra hot water tank off the RFC no less, but didnt bother but left the cable coiled up in a corner live, I found the break as it were on a continuity check but it took a whole day to find the other end they had joined the cable in a round jucntion box and pulled it up the cavity
Pict

 

[MarkieSparkie]

... I now found myself underneath 100 tonnes of molten iron burning it’s way out. PANIC!
It wasn’t only me in panic mode, is a “clutch” of managers/directors in headless chicken mode the right term? The entire works was shut down for a week for us to do the repairs.

Flock or brood of chickens, mate ... Flock the most appropriate in this case ... As in lets get the flock out of here!:jester: