Jim Lux wrote:
>> The power company also grounds the
>>neutral connection at the transformer to earth ground.
>
>Not necessarily.. for the same reason as you have a single interconnect
>between neutral and ground. You don't want neutral return currents
>flowing back to the transformer via the ground path.
>
>Also, if the neutral opens between your house and the transformer
>(which does happen, particularly on an overhead service), you don't
>want the entire neutral return current flowing through ground. You'd
>rather have the voltages on the two sides become unbalanced. Radical
>voltage fluctations may destroy equipment, but at least it doesn't
>create a shock safety hazard.
Interesting... the power companies in the UK take a different view. In
the event of a neutral break in their local distribution system (230V
single-phase, neutral close to earth potential) they'd rather have the
return current flowing back through earth than create a shock hazard due
to the neutral becoming hot.
Therefore they almost always earth the neutral at the transformer,
and/or anyplace else they conveniently can. Having made that policy
decision a long time back, they have created the expectation that
neutral will be safe to touch when doing household wiring work, so now
they're perpetually locked into that policy.
--
73 from Ian G/GM3SEK
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