23 Nov
2014
23 Nov
'14
5:46 p.m.
On 23/11/2014 22:12, Brent Hilpert wrote:
The benefit of the North American split-phase system
vs EU/Britain is
you have the energy & copper-efficiency of 240V available for heavy
appliances, but you have the safety factor throughout the house of
never having more than 120V between you and earth.
That's not as much of a safety factor as many people think, indeed
possibly not at all. It's true that 230V will give you more of a jolt
than 120V, and more so because human body resistance drops slightly at
higher voltages. Nevertheless, there's a strong argument that a 230V
jolt is more likely to throw you off the conductor whereas 120V may be
more likely to make you latch onto it. It depends how you touch it,
obviously, but evidence suggests that (EHT excepted) the region around
100V-130V is about the most dangerous. I recall reading a discussion of
that as part of the European harmonisation of voltages, in connection
with 110V for site equipment. Evidently that was in part why the idea
of one live and one neutral with a single simple MCB or RCD was rejected
in favour of the split 55-0-55 system (proposed by the UK).
--
Pete
Pete Turnbull