What was the fault?

[bernardgreen]

When you say tripping. Can we assume it was MCBs tripping on current overload or was it RCDs tripping.

Because if it was RCDs then it opens up so many possibilities in other circuits that share the neutral bars.

 

[IJWS15]

You miss the point - the forum is already clogged with stuff the DIYer doesnt need to know, and you have added to that.

Just my 2p

As a DIYer I find these posts interesting and informative. Anyone not interested can press "go back".

 

[Lectrician]

No RCD's - All wiring is PVC/PVC in galv trunk.

After a little poke around in the cherry picker, found a nasty enclosure used to join some cables where the trunking had been altered previously.

As soon as I opened it up and realised some of the lighting cables had been joined I kind of knew what the problem was!

Phase to phase boom. Obviously not always arcing across, as would last days, and not a good clean fault as switching on one row would bring on the other!

 

[ban-all-sheds]

They don't look too small to carry the current - what caused the original failure? Screw not tightened?

 

[Lectrician]

They are 4mm terminals, forget what rating they usually are for din rails, but ample.

I would have suspected a loose terminal, but the terminal was tight, or appeared to be. Often difficult to judge if a terminal is tight enough after an overheat.

Glad it was *pretty* quickly sorted!