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Discuss Lighting problem Melted Cable in the Electrical Forum area at ElectriciansForums.net


New EF Member
Hello, Called out to look at lighting problem in a house, found a section of cable in loft looking melted, see photos. Anyone know what's caused the cable to melt, don't think its over loaded as its only got 7 lights on it, doesn't look burnt to me. Was thinking it may have come into contact with chemicals?





Admin and gender confused
Staff member
Looks like overheating. Is the cable sheath rigid and crispy?


Electrician's Arms
I have seen cable cooked in insulation right next to 50W 12V lamps and transformers, but your pic looks too long a run of heat affected area, implying the conductor really was overloaded. Can you confirm the cable insulation now gone hard and brittle? Or has the cable insulation turned soft and soggy?


New EF Member
Yes its from a lighting circuit 1mm T&E cable. It had usual loft insulation over it. I didn't think it was over loaded as its not got black burn marks, it is sort of crispy but is still a little flexible. Looks like two cables melted together, when trying to separate them the plastic sort of tears away from the copper, it is stiff but not crumbly as I would normally expect from a cooked cable.


Regular EF Member
Has there ever been a loss of neutral on the supply to the property? Working for Dno if there was a three phase system feeding a street for example, and the neutral was lost then this can happen, in fact it is one of the worst problems, as all properties on the circuit have to be disconected and inspected, although with modern 1000 volt cables this shouldn't happen.


Electrician's Arms
Is it a TT property? If there is a N-E fault on the light fitting and a L-E fault elsewhere on the property guess where the fault current goes...

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