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Service cable and cut out too hot.

broadgage
I was called by a local hospice to investigate "overheating" and found the DNO service cable and cut out to be alarmingly hot, I would estimate the surface temperature of the service cable to be at least 60 degrees. Definite smell of hot PVC.

Enquires suggested that the supply was originally 60 amps, single phase and was upgraded to 100 amps by fitting a larger fuse.


Measured load was just just under 100 amps, it probably exceeded 100 amps if anyone used a kettle.Service cable looks like only about 10mm. Voltage is rather low at 221 volts, but just within tolerance.


Is it worth calling the DNO, or will they simply say "supply working, do not worry" I suspect that the service cable is very undersized, but am aware that DNOs work to different rules.


I have moved combustibles away from the cable and advised reducing the load a bit,


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  • 0
    This might sound like an odd question, but what colour is the cut-out?


    I came across a similar problem (office, 3-phase supply, one phase taking 80-odd amps most of the day, possibly a bit more when the kettle was in use) - 100A fuses in modern-ish black plastic cut-out - terminal had burned out. DNO's explanation was that the black cut-outs, although marked 100A, are only rated for 100A intermittently and are only really good for 60A continuous. They changed to a grey (100A) cut-out and all then seemed well.


    So the presence of a 100A isn't really grounds for assuming that the supply is capable of providing 100A continuously. Personally, I'd call the DNO - but they might be of a mind to treat it as a request for a supply reinforcement and want to charge accordingly.


      - Andy.
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  • 0
    This might sound like an odd question, but what colour is the cut-out?


    I came across a similar problem (office, 3-phase supply, one phase taking 80-odd amps most of the day, possibly a bit more when the kettle was in use) - 100A fuses in modern-ish black plastic cut-out - terminal had burned out. DNO's explanation was that the black cut-outs, although marked 100A, are only rated for 100A intermittently and are only really good for 60A continuous. They changed to a grey (100A) cut-out and all then seemed well.


    So the presence of a 100A isn't really grounds for assuming that the supply is capable of providing 100A continuously. Personally, I'd call the DNO - but they might be of a mind to treat it as a request for a supply reinforcement and want to charge accordingly.


      - Andy.
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