On Thursday, 16 November 2017 20:05:21 UTC, Roger Hayter wrote:
whisky-dave wrote:

On Wednesday, 15 November 2017 19:44:09 UTC, T i m wrote:
On Wed, 15 Nov 2017 09:00:17 -0800 (PST), whisky-dave
wrote:

snip

They mean (clearly) 'The power distribution network'.

yeah clearly like 220-240V will give you 2KW clearly it doesn't matter
what the voltage is or does it.

What do you think? P=VxI

Yep so 220V wouldn;t give the same power output as 240V would it but
according to the label any voltage from 220 to 240 will give 2000W not
about 2KW not 2001 not 2002 ....

snip

I think that has to be regarded as a 'rating' rather than an electrical
function statement.

Personally I think it;s a maxium rating if used withint that voltage range also not that they specify the frequency while that isnlt expected to change I'm not sure what would happen if at 220V the frequency double or halved.

In reality the 2kW will be at a particular
voltage, usually 240V in the case of electric showers which have a
similar rating system.

Because 240V is the maxuim continous voltage suplied by the gird to households.

One can then be pretty certain that the power
output will be about 1700W at 220V. (Mental arithmetic plus binomial
theorem rather then precision calculation.)

Yep I agree that's why I wasn;t bother bother with teh 1.7KW result I got.
With 5 heaters on the same circiut I was getting about 1.6KW which again I wasn't concerned about.


BTW, I am quite sure they would not claim the 2kW was precise to the
nearest watt at any voltage. +/- 5% would be a reasonable achievement,
say 1.9 to 2.1kW. Or it could be a maximum, then 1.8 to 2.0kW. In the
latter case the 220V power might be as low as 1500W

So I was suprised to find that I was getting just 700W from a full on 2KW heater.