>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.