Lights dimming several times over the course of an hour in Edinburgh

[username132]

Over the past hour in Edinburgh lights have dimmed at mine and friend's homes and one of the ASDA supermarkets I happened to be in. According to SP Energy Networks (apparently they're responsible for this part of the UK grid?) website there are no faults detected in my area and some websites give the national frequency as just over 50 Hz which I figure is healthy enough.

Any idea what causes this and is there a way to monitor different areas of the power grid? I guess there can be local variations in the voltage and frequency. Presumably these are measured by power companies - do they keep the information to themselves?

 

[flameport]

I guess there can be local variations in the voltage and frequency.

Voltage yes. Due to varying loads, or faults such as loose connections.

Frequency is the same everywhere.
If the frequency varied enough to cause problems, it would not be a small area with dim lights - large sections of the country would have no power at all and it would be a major disaster.

 

[SimonH2]

If it only happens the few times and then stops - there's naff all anyone can do to figure out what it was.
If it continues, then there are loggers that can be plugged in which will detect and log such dips. If there's a continued problem you may be able to persuade the DNO (SP in your case) to put one in for a while. If it shows problems, they'll investigate further.