Dave Plowman (News) wrote:
In article ,
Gerard Bok wrote:
His 240 volts are likely to be one leg of a 380 or 400 volts
3-phase system.
Kill it's neutral and the lights all shine. Briefly :-)

How? Remove the neutral and you have no current flow in a single phase
system like all houses in the UK have. You only get your '380 or 400
volts' between phases in a three phase installation.


Yes but remember that electricity is often distributed as far as your
street in 3 phase - your house might be on L1, the next house on L2 and
the next L3. Of course, losing the neutral connection WITHIN YOUR HOUSE
will not cause an overvoltage situation, simply a power failure.
However, losing the neutral further up the distribution system e.g. at
the pole transformer or substation could cause overvoltage because the
neutrals of all the houses will still be commoned together and the
houses are not all fed from the same phase. Therefore you could have
415V across yours and your neighbours house installations, the common
neutral serving as the link. What you now have is a potential divider
in electronics terms and unless both houses had absolutely identical
appliance loading, one house is going to get a greater share of the
voltage than the other possibly resulting in damage to appliances.

--
Tim Phipps

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