On 15/04/2018 12:19, Fredxx wrote:
On 15/04/2018 12:12, newshound wrote:
On 14/04/2018 23:59, Dave Liquorice wrote:
On Sat, 14 Apr 2018 21:13:38 +0100, charles wrote:

ask your supply co to install a voltage logger.

Just report the "high" voltage, 250 is only 3 short of the permitted
maximum. The DNO for here jumps pretty damn quickly at reports of
wide voltage variation and/or approaching the limits.

If they do install a logger you don't get to see the data.

High voltage will shorten the life incandescant bulbs quite a bit. We
used to get through a bulb every week or two. Bought a UPS plugged it
in it went straight into voltage reduction mode. Measured voltage,
250 ish, rang DNO, engineer at door two hours later, transformer
tapping adjusted next or the day after, bulb consumption fell
noticabley...

I wouldn't expect a 1? 2? kW water heating element to be as sensitive
to voltage as light bulbs unless it's really cheap and nasty. Or made
such that 240 is the max rather than nominal voltage...

This is one of the mysteries, there are a couple of incandescent bulbs
and AFAIK they are not prone to failure. These are 2.3 kW heaters. As
an alternative to logging data, I suppose I could knock up a
diac/triac "dimmer" to drop the power by (say) 10%.

I'm with Dave here. As long as the unit doesn't become dry I wouldn't
expect it to be sensitive on voltage. Methinks a failing batch.

The fact incandescent bulbs can cope with the higher voltage just
confirms these thoughts.

It is possible your DVM reads high. Some are very poor at measuring rms
voltage.

This one read 240V at home. But I will try again with the Robin PSC/loop
tester which is probably more accurate.