Andy Bennet wrote:
On 29/11/2018 20:30, Bruce Farquhar wrote:
Those cheap Chinese water heaters which are simply two plates of
metal, one on live and one on neutral, how can they work?* Because the
resistivity of tap water apparently varies from 2 to 200 ohm metres.
That's a range of 100 fold in possible power output.* I assume the
resistivity changes due to impurities like lime in hard water areas?

Big Clive did a review of these a couple of years ago
https://www.youtube.com/watch?v=EViyccc2t9w

and John Ward more recently
https://www.youtube.com/watch?v=0BPCife3tWs
Big clive is more accurate, the other nong was making factually
incorrect statements.