Why this extra wire?

[amfisted]

I changed one further single socket for a double yesterday (making three in all, and I think that's enough) and in this case there were six cables coming into the box rather than just three. So I understand why questions were asked as to whether the other two might be spurs, or (horror upon horror), spurs off spurs.
The spark passed the installation last year so I ain't gonna worry about it.

 

[amfisted]

Well, now I am slightly more worried because an RCD tripped during the night, and it was the circuit on which I've fitted the converters. I reset it and so far its remained on (about two hours now), but I'm scratching my head as to what might have gone wrong. Never had any such unexplained fault prior to fitting the converters.

I've been using the converted sockets fairly regularly now for a couple of days, but only one was actually in use during the night; my missus was charging her tablet on it. During the night she'd switched off and disconnected the charger, so I'm thinking maybe she'd struggled to turn the socket switch off, as with these converters the switch is a slightly different size, shape and position, and she has trouble with her hands. Maybe she inadvertently held the switch in the twilight zone between on and off for a split second, and that tripped the circuit.

I have a BEHA Unitest socket tester that I got from a DIY shop a few years back: one of those that illuminates combinations of lights to show whether you have a wiring fault (though presumably, your system would already have tripped if you had). I would imagine that professionals look unkindly on such DIY testing equipment, but at the time it seemed like a good idea to have at least some way of checking fault status without spending too much on equipment which would rarely be used. Anyhow, it displays PE and L lights when plugged into the new sockets, which according to the guide on the front of the tester indicates OK.

My question is this: if there's a fault on the wiring in these converted sockets, why does the socket tester not show a fault status, and why, if a fault exists, did the RCD not trip right away when I restored power after fitting the sockets? I suppose it could be somewhere else in the system and nothing to do with the converters, but this has never happened here before (we've been in this property just under a year) and it would be a bit of a coincidence if an unconnected fault occurred just days after fitting the converters.

Apologies for the length of the post, but I've been criticised in the past for not giving enough detail, so I thought that in this case I would go for overkill.

 

[riveralt]

Check your wires are properly terminated in the new sockets - sometimes you can trap the insulation and sometimes they can wriggle loose when you refit them.
One tightened I was always taught to give them a good yank to make they had all held.
Loose wires making a poor connection can cause heat build up.

 

[amfisted]

Thank you, I'll do that. I do recall that when the system was checked by the spark last year, he found a loose connection in that particular socket which was causing it to warm up. He reconnected the loose wire, but maybe in changing over I've fallen foul of the continued absence of slack. I'll have another look at it.