On 17/04/2018 12:29, NY wrote:
"newshound" wrote in message
o.uk...
Unless you read it in the context of US (and possibly French and other
continental?) systems, where neutral isn't.

So in America and (parts of) mainland Europe, is neutral not connected
to earth potential at some point in the distribution chain?

About the only situation where it might not be the case is with an IT
style feed from a generator or inverter. That may have both sides
floating with respect to true earth. I am not aware of any actual fixed
distribution systems that operate like that though.

I can see that a earthed-centre-tapped transformer for supplying 220V in
addition to (2x) 110V supply will have a higher potential between live
and neutral than between live and earth, and hence higher current,
higher ability to kill etc.

Yup you will get higher shock currents between the two ends of the
centre tapped transformer than between one end and the centre. However
both will be lethal in the wrong circumstance.

But is the potential between 110V (or 220V
in Europe) live and neutral significantly greater than between live and
earth?

No, if anything it may be slightly less (depending on the earthing
scheme). Under load the neutral will tend to rise a little in voltage
near the load end, and the line fall a bit, reducing the potential
difference. If the earth is independently connected back to the
transformer or substation (i.e. TN-S) Then it won't see this voltage rise.

(that's why a neutral to earth short often causes a RCD trip)


--
Cheers,

John.

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