Burnt out cables (Pics)

[Lectrician]

Call out to no power to sockets. Found 3036 fuse blown (and by the looks of it, had done several times!).

Voltage operated ELCB in place on a TT system, 5.8ohm Zdb.

Rodent damage in loft, causing earth fault.

The earth fault on the cable would cause around 40amps to flow, damaging the 2.5mm T+E - every so often an L to N fault blowing the fuse with a bang.

Have replaced damaged cable, checked insulation resistance, and have fitted an RCD temporarily while quoting to replace fuseboards initially with a view to a rewire.

Quite shocking - a real fire risk.

 

[JohnW2]

Voltage operated ELCB in place on a TT system, 5.8ohm Zdb. Rodent damage in loft, causing earth fault.

Sounds like one of those cases in which the main bonding has prevented the ELCB from operating in response to the earth fault?

Kind Regards,John.

 

[Lectrician]

Exactly why the ELCB's are to be condemned when seen.

 

[JohnW2]

Exactly why the ELCB's are to be condemned when seen.

Quite so - although, to be fair, I suppose they do what it says on the tin, and what they were presumably designed to do - namely operate if the potential of CPCs rise to 50V (or whatever) above earth potential. However, since such a rise in potential is not really that much of an issue if adequate 'main bonding' is in place, I wonder if such bonding was less in evidence in the days when VO ELCBs were introduced?

Kind Regards, John.