>On Sat, 23 Aug 2008 00:35:42 GMT, Richard Sherratt
>NOTHINGHEREbrunsley.com.au> wrote:
>

>>On Sat, 23 Aug 2008 00:53:15 +0100, Humbug tofee.net> wrote:
>>

>>>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.

>>
>>The maths is slowly coming back to me. 240 * root3 = 415.7.

>
>Well done. I'd forgotten the maths.