Had a floating pump go very very bad today and cleared two DNO fuses. Given we've got 100A fuses in a switch fuse and they have 100A in the cutout it's always 50/50 but this time their fuses were faster.

Reported the fault and in under twenty minutes they had a guy on site. Who re-fused the cutout with no hassles and left us to play

So, perhaps the DNO's aren't quite as bad after all.

Didn't stop me getting slightly damp and covered in the remains of a well burnt 40kw motor but at least the supply was back.


Stu

I deal mostly with Scottish Power networks and have to say that in the majority of cases the guys on the ground are really accommodating, especially on emergencies.

That said, on a call out at the weekend, it took SP 30 hours to respond to a high Ze on a TN-S supply - I suspect however this has more to do with cost savings by the parent Co, Iberdrola. Now they have an external dig, with no start date offered!

Who was the designer? Should there have been a charge by "they"?

Regards

It is not an ideal design, but sometimes cant be readily avoided.
If the motor needs 100 amp fuses to avoid blowing them on starting, then the fuses in the customers installation cant be downsized.

It would be very extravagent to ask the DNO for a 160 amp or 200 amp service, for a load of less than 100 amps, simply to avoid operating the cut out fuses on hopefully rare faults.
Most motor faults result in an overload that should operate the thermal overload relay without blowing fuses. In case of a short circuit then operating the cut out fuses has to be accepted.

I would normally expect the DNO to replace blown cut out fuses without charge, provided that this is a very rare event.
If it happens regularly, then that suggests that either the service is too small, or that the customers installation is defective.