Faulty cable?

[leezer3]

Would like a second opinion please
Three days ago, I did a small amount of socket moving. Basically:
* Blank faceplate, where the original socket position was blocked by the old boiler.
* Cables running through chocblocks in this faceplate, and down to a surface mounted backbox.

I removed the blank faceplate and original backbox & substituted for a 2x singles backbox.
I then terminated cable #1 into a FCU on the first position. Cable was very tight, so I elected to terminate cable #2 into chockblocs, and then install links to a single socket and the FCU.
A little messy, but nothing AFAIK wrong with it.

All of these links I did with a small section of the inner cores of the original T+E salvaged from running down to the surface mounted backbox, with the reasoning that it was better to keep the color scheme consistant within the socket.

I checked for stray voltages and misplaced continuity between cables, and then put everything back together, followed by a voltage test at the socket & FCU- everything looked normal.

Last night then, the breaker for these sockets (16a radial) & by extension the main RCD tripped.
Opening up the socket again, I found a discolored section on the linked live, which when removing the wire pretty much snapped.

I've replaced the three wires from the offending link with a brand new section of T+E, and all appears well again.
I'm thinking faulty wire, either a nick in the insulation, or snapping when bent by the frontplate. *Don't* think I nicked it with the screws or between the backbox and frontplate, but it's always a possibility.

Apologies for the essay, but would appreciate a second opinion on what went wrong. Replacing the whole lot including stuff in the walls is obviously a possibility, but one I'd obviously like to avoid, as that goes well outside my area of comptence as a reasonable DIY-er

 

[ericmark]

I would guess a lose connection. I have in the past found that chock blocks have had either wires stuck in threads or faulty threads so what seems tight is in fact a lose connection. Using maintenance free connectors either spring or crimp is better in places where you are likely to forget there was ever a connection.

As electricians the loop impedance tester is a valuable tool as it often highlights faults when used on a regular basis. One gets to know what to expect and reading which are higher than expected normally point to pour connections as do variable readings.

The fact that we have to enter the readings on the minor works certificate means we always use them. The cheap DIY versions like the Martindale EZ150 Earth Loop Plug Socket Tester only have 6 lights (3 green and 3 red) so between 1.7 ohm and 5 ohm there is no indication as to where the reading lies so they will not alert one in the same way as a proper tester and even the cheap ones cost £45.

 

[leezer3]

Cheers, I'm keeping an eye on it, but all seems fine at the minute.

Can't say I much like the idea of crimps, getting a crimper into a backbox is probably a pig of a job

It's situations like this I sometimes think I need some more tools, but the trouble with that is that I'd be using it a couple of times a year at best, with a significant investment for something that's worth using.
Suppose I could rig up a flying lead and test to the main earth block, but the problem in this instance was with the live core