Socket Spur

[CRANEPB]

I have added a spur from an existing socket that is on a ring. I have performed continuity tests to confirm that the existing socket is part of a ring. There are 2 cables coming into the existing socket.

I have an older style CCU where overcurrent protection is provided by fuse wire that is mounted in a removable module to BS3036. I identified the module for the associated ring which was rated at 30A and removed it from the CCU to provide isolation. After I had completed the work I put the module back in the CCU. As I pushed the 30A module into the unit I witnessed a spark in the CCU. I removed the module. The fuse wire was still in tact. However when I inspected the wiring for the spur it had been damaged. Why was the spur wire damaged and not the wires associated with the ring? Is this because the ring distributes any current overload throughout the ring. One thing I must add and that is my wife had just turned the hot tap on which is heated by a combi boiler which I did not realise was on the same ring. The boiler is protected by a separate fused point which did not blow. Any help would be greatly appreciated!

 

[securespark]

What sort of damage?
Could it be coincidental?

There is always a "splash", spark, arcing whatever, when you replace a fuse on a circuit where current is being drawn. That is normal.

Describe the damage that happened to the spur wiring.

 

[CRANEPB]

Thanks for the quick response. There was a black mark on the wall around the socket where the spur was being taken from. When I removed the socket the insulation on the live and neutral wires going to the socket spur had overheated and was out of shape (melted also when I went to disconnect the wire they broke about 3cms from their respective termination points. Something I should also highlight is that I replaced the ring socket with a new one when I added the spur.

 

[ban-all-sheds]

You must have shorted something out when you wired it up.

Do it all again, with more new accessories and cable. Check the ring cable very carefully for damage.

 

[plugwash]

it sounds like there was some degree of undesired connection but not a dead short (a dead short would have blown the fuse)

either that or whats in your rewirable carrier is not fusewire

 

[CRANEPB]

I rewired the spur and everything works. As you stated there must have been a short in my original spur wiring. One thing that should be noted is that my measuring instrument has the facility to detect a live conductor, measure voltage, detect resistance (impedance?) and continuity. However when I disconnected the supply to the ring I was working on I placed one prong of the instrument on the metal enclosure of the original socket the instrument detected that this was a live element (with the power disconnected??) When I placed the other prong on one of the wires associated with the original ring the instrument was detecting a resistance. Do these factors help in concluding what happened with my original spur wiring?

 

[Millennium_Boy]

Pull the circuit fuse, stop using the affected circuit, and call a qualified electrician to check it over.