I've just seen this article in E&T highlighting the increased incidence of reported broken PEN's from 57 in 2003 to 474 in 2021. It seems they are becoming less of a rare event.
David
I've just seen this article in E&T highlighting the increased incidence of reported broken PEN's from 57 in 2003 to 474 in 2021. It seems they are becoming less of a rare event.
David
In my view we should return to TN-S, with 4 core street mains and and with wire armouring used as the earth.
Option one. Old style mains with the wire armouring exposed and in direct contact with the general mass of earth. This approach gives a very low earth resistance since the armouring provides both a metallic earth path back to the transformer AND numerous fortuitous additional earth connections along the cable.
Option two, use the more modern type of 4 core cable with a plastic outer covering. This protects the wire armouring against rust. If selecting this option then extra connections to earth should be provided at each joint.
We could now add to that bring back TN-s campaign, some basic condition monitoring at the substation, and a little box with a SIM card that rings in its earth leakage current readings, electrode resistances and instantaneous HV and LV load currents, for the price of digging a decent foundation, thus allowing the DNO transformer and cables to be preemptively maintained and overload to be realized before the paint blisters off the transformer.
Unfortunately the same acute constriction of the wallet that gives us the broken PEN problem in the first place probably means this is also off the table. But I agree, it would be good.
The safest alternative is probably to stop worrying about earthing altogether and adopt a similar approach to that now taken for garden appliances outdoors, and make everything 2 pin and double insulated.
Mike.
We could now add to that bring back TN-s campaign, some basic condition monitoring at the substation, and a little box with a SIM card that rings in its earth leakage current readings, electrode resistances and instantaneous HV and LV load currents, for the price of digging a decent foundation, thus allowing the DNO transformer and cables to be preemptively maintained and overload to be realized before the paint blisters off the transformer.
Unfortunately the same acute constriction of the wallet that gives us the broken PEN problem in the first place probably means this is also off the table. But I agree, it would be good.
The safest alternative is probably to stop worrying about earthing altogether and adopt a similar approach to that now taken for garden appliances outdoors, and make everything 2 pin and double insulated.
Mike.
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