On 12/05/18 08:08, Brian Gaff wrote:
I'd have thought with the current state of electronics, it could be arranged
that the earth was mainly from the house and a circuit between the local
ground and the main earth could be monitored and the whole lot cut off if
the potential rose to outside tolerances.

Non starter - you are absolutely not allowed to have switching elements
in the protective conductor.


In the murky past I've actually just bonded the incoming earth both to any
local mass and a ground rod, and nothing ever went bang or caught fire!

You can do that (and may have to if you run a backup generator, and it
*might* be a feature of the upcoming 18th Edition of the Wiring Regs)

I can see however that there could be circumstances where a earth is
effectively from live to earth and it would be hoped that before the whole
lot failed or caught fire, the local fuse for that circuit be it breaker or
whatever would trip and isolate it all.

Againt, you're not allowed to put fuses in the CPC.

Of course there are other issues as has been mentioned before to do with
nasty noise on the mains etc, but that would probably only affect somebody
looking for electronically quiet supplies.

I do sometimes wonder as complexity goes up in this apparently simple
wiring, if we are not making things so awkward nobody will understand it and
just ignore it, which is also a danger.
Most folk around here I notice still just string some mains cable down
their fence and fit a 13 a socket in the shed.
Brian