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Caravan hook up
Former Community Member
Hi I am fitting a caravan hook up on the wall next to the dno incomer box. No wires exposed. Do I still require an earth rod. The earth bond will be prob 1 ft long inside so not exposed. I know if I fit the box away using swa then yes earth rod would be used.
as the risk of loose of earth would be very reduced as its so short
The issue isn't the risk of a break in the PE/c.p.c. between the intake and the caravan (that wouldn't immediately produce danger unless there was a simultanous L-PE fault in the caravan or there was high earth leakage equipment installed) - the worry is a break in the distribution network's combined neutral & earth (CNE or PEN) conductor. If that happens it would not only mean the loss of earth, but as there's almost certainly some loads connected, the severed neutral/CNE would be immediately pulled up to something approaching full mains voltage - and as the installation's earthing system is connected directly to the CNE under the PME system a single fault can cause all earthed metalwork to be very hazardous live - and for an indefinite period (i.e. until someone notices, calls the DNO and they send someone out in a van to fix it). That's not too bad inside a building where everything should be bonded together anyway, but outside where someone is likely to be in contact with the general mass of the earth, it's a different story.
That's why it's only an issue with PME (TN-C-S systems) - true TN-S systems don't have the same immediate hazard.
as the risk of loose of earth would be very reduced as its so short
The issue isn't the risk of a break in the PE/c.p.c. between the intake and the caravan (that wouldn't immediately produce danger unless there was a simultanous L-PE fault in the caravan or there was high earth leakage equipment installed) - the worry is a break in the distribution network's combined neutral & earth (CNE or PEN) conductor. If that happens it would not only mean the loss of earth, but as there's almost certainly some loads connected, the severed neutral/CNE would be immediately pulled up to something approaching full mains voltage - and as the installation's earthing system is connected directly to the CNE under the PME system a single fault can cause all earthed metalwork to be very hazardous live - and for an indefinite period (i.e. until someone notices, calls the DNO and they send someone out in a van to fix it). That's not too bad inside a building where everything should be bonded together anyway, but outside where someone is likely to be in contact with the general mass of the earth, it's a different story.
That's why it's only an issue with PME (TN-C-S systems) - true TN-S systems don't have the same immediate hazard.
