On 02/02/2021 00:00, John Rumm wrote:

We have a HV cable fault a couple of weeks back. It caused a power cut
for a couple of hours in the morning. Then came back when they "fixed"
it (turns out they just routed round it and stuck in some temporary
gennys - because it was underground and worse than they expected).

We then got another power cut a few hours later during the early
evening, while they actually fixed it. (had to cook dinner on the two
burner gas ring set I normally drag out to sit beside the BBQ!)

When they fixed it for real, and the power did come back it was clear
not all was well. The voltage was sat about 200V. Most things worked
ok, although lamps were dimmer - even LEDs. The most notable exception
(which drew my attention to the voltage) was the microwave turntable
motor sound "weaker", and there was pretty much no heating effect at
all for anything you put in the oven.


I remember I was sat one summer evening watching the TV (this was 1998
ish, so a CRT telly). I thought, but wasn't sure that the scan
momentarily collapsed and restored.
Didn't think any more of it, but then a few mins later the phone/answer
phone that was powered by a wall wart started bleeping and clicking. The
LED call indicator was randomly flashing digits, and they were dim. I
pulled the connector out of the unit, and measured the DC volts from the
wall wart, it was only 4 or 5 volts (should have been 12 I think)
At that point the doorbell rang, it was my neighbour. She asked whether
I had any power. Well yes, I said, and went to switch on the hall light
to prove it. The bulb just gave a tiny glow.
All the pennies dropped at that point !Â* I hit the main breaker on the
CU, and then just energised the lighting circuit alone. Measured the
voltage, it was 80 volts.

The remarkable thing was the TV had been perfectly happy working at 80
volts. That's SMPSUs for you I suppose. I bet its mains flex was warm
though ?