John Rumm wrote:
Andrew Mawson wrote:

and you're worried if perhaps there is a safety issue - and perhaps
sound a little panicky G (and should all that snow have melted SO
quickly arround their transformer last winter)

As Andy mentioned in another post, there is a potentially serious safety
issue here.

All the circuits in your house will be protected by overcurrent devices
which you expect to open fast enough to clear a fault should one occur,
and without the wiring in the house suffering damage as a result. With a
much lower than expected voltage, you can no longer rely on this being
the case since you are outside the design parameters of the circuit and
cable, and it will take longer than expected to open the protective device.

The problem is compounded if you have a supply with Neutral and Earth
combined at the origin of the installation. Your high supply impedance
will also translate into a high earth fault loop impedance. Which in
turn could leave metal work rendered live due to a fault, in that state
for much longer than expected (assuming the circuit is no RCD protected).

If you refer to appendix 2 of the on site guide, this lists the maximum
allowable impedances for different protective devices. Note that this is
the impedance measured at the far extent of the circuit in the property,
not at the CU, and hence includes the loop impedance of the house wiring
as well as that of the supply.

For example a 30A rewireable fuse is only safe with impedances up to
0.91 ohms. A type B 32A MCB 1.2 ohms


I think most pole mounted transformers simply have an earth strap
running down the pole..connected to neutral ..and a local earth spike.