25-06-2014, 06:57 PM
In days of old, when Knights were bold, etc, etc, a typical UK Domestic Installation consisted of a Substation feeding a Street or Streets with 3 Phase. Each house got a Phase and Neutral and provided its own Earth, typically the incoming Lead Water Pipe or other suitable arrangement. Thus every third House was on the same Phase. The snag is that any unbalance Current flows back down the Neutral, and there would be Voltage on it. At out last house you could often find 30 Volts on the Neutral, and bear in mind that it's backed up by the Sub. If you lost the Neutral somewhere, typically due to corrosion or damage, the whole of the 'Dowside' would rise to Phase Voltage. It was generally OK when the consumption by each House was low, but as lots of high Loads were added the problem got worse. The solution was to bond the Neutral to the incoming Earth, provided with the Supply, at each Meter point, hence 'Multiple Earthing'. Now any unbalance Currents flow to Earth at each House. I believe it was also driven by the use of Plastic Water Pipes where you could no longer rely on the incoming Pipe to provide you with a decent Earth. Note that Bonding the household Metallic Pipes to Earth is NOT to Earth the Supply, it's to Earth the Pipes - Eqipotential Bonding - so you won't get a shock between Neutral and a Pipe.
There's a proper explanation on the Net.
Come on Lawrence, you're good at finding these things.
Alan
There's a proper explanation on the Net.
Come on Lawrence, you're good at finding these things.
Alan
