>On Sat, 16 Aug 2008 09:52:37 +0100, Ben newsam
>gmail.com> wrote:
>

>>On Sat, 16 Aug 2008 08:23:26 GMT, Richard Sherratt
>>NOTHINGHEREbrunsley.com.au> wrote:
>>

>>>There's some complicated maths involved and it's nearly 40 years since
>>>I studied it, so my head is dead. We're dealing with ac current, so
>>>that means we need to understand sine waves. [1] That means that the
>>>voltage is affected by the angle. Clear as mud, right :-)
>>>
>>>Three phase voltage in a 230-240 volt system is actually around 400
>>>volts. One of the times we lived in Germany (Bielefed, I think), the
>>>oven had a three-phase 400 volt supply. Thre square root of 3 is
>>>involved.

>>
>>Yes. I remember, in Germany, that the water heater above the sink in
>>my shower room had a three-phase conection. I asked an electrician if
>>it was safe and he said yes of course but don't mess with it. It
>>didn't look safe to me. I was under the impression that it was about
>>450 volts rather than 400, but it was all a long time ago and my
>>memory might be faulty. I also remember being told that if there is a
>>short circuit between phases, the voltages involved can be huge and
>>all sorts of weird things start to happen. You know, Bad Things, as in
>>Ghostbusters when the lines cross.

>
>It's 415 Volts between phases. I installed a German (Siemens AIH)
>water heater in my house (as it was then) with a big fat armoured
>3-phase cable.
>
>It's safe.