Strange mains electricity issue
Discussion
Earlier in the week there was a thunderstorm during the night and the power went off. Then on for a while, off again and was eventually restored late in the morning. (Chandler's Ford, Hampshire).
Having reset the clock on the microwave, oven and water softener we then went out leaving the NAS to sort itself out.
Coming back to the house in the early afternoon I popped into the downstairs loo and noticed that the light and fan didn't come on. Checking round the house I discovered that no lights actually worked (all CFL, LED or halogen on electronic transformers). However, the microwave display still showed the correct time, the Tivo and the Sky box still had power lights, the computer was still blinking its standby light and the router was running. It looked like the lighting ring had no power, but checking the consumer unit showed nothing that had tripped.
So I put the kettle on so I could ponder this - the blue LED lit but no water heating occurred. The display on the front of the oven was off, but the NAS was still busy re-syncing its drives connected to the same ring.
Then I went into the garage to get a multimeter, and the mains halogen light in there managed to provide about as much illumination as an electric fire.
Very odd.
Measuring the mains voltage showed 70 volts RMS.
At this point the lady next door knocked and asked if our electricity was ok, since the solar panel controller in their garage was making a lot of disturbing noises and was showing a message 'grid imbalance'. No panels on our house.
After a while I heard a few local house alarms going off as the normal mains voltage was restored, and everything went back to normal. Nothing seems to have been damaged, and I doubt whether anything is likely to be damaged by too low a voltage anyway. Maybe running halogen bulbs orange rather than white would spoil the normal way they maintain the filament, but probably not in a few minutes.
So, any ideas about what was happening? Could we have been running on next-door's solar feed-in?
Having reset the clock on the microwave, oven and water softener we then went out leaving the NAS to sort itself out.
Coming back to the house in the early afternoon I popped into the downstairs loo and noticed that the light and fan didn't come on. Checking round the house I discovered that no lights actually worked (all CFL, LED or halogen on electronic transformers). However, the microwave display still showed the correct time, the Tivo and the Sky box still had power lights, the computer was still blinking its standby light and the router was running. It looked like the lighting ring had no power, but checking the consumer unit showed nothing that had tripped.
So I put the kettle on so I could ponder this - the blue LED lit but no water heating occurred. The display on the front of the oven was off, but the NAS was still busy re-syncing its drives connected to the same ring.
Then I went into the garage to get a multimeter, and the mains halogen light in there managed to provide about as much illumination as an electric fire.
Very odd.
Measuring the mains voltage showed 70 volts RMS.
At this point the lady next door knocked and asked if our electricity was ok, since the solar panel controller in their garage was making a lot of disturbing noises and was showing a message 'grid imbalance'. No panels on our house.
After a while I heard a few local house alarms going off as the normal mains voltage was restored, and everything went back to normal. Nothing seems to have been damaged, and I doubt whether anything is likely to be damaged by too low a voltage anyway. Maybe running halogen bulbs orange rather than white would spoil the normal way they maintain the filament, but probably not in a few minutes.
So, any ideas about what was happening? Could we have been running on next-door's solar feed-in?
I understand the brownout idea, but I wouldn't have expected a voltage right down at 70. I've now found a report from Southern Electric that says: 'there had been some quite significant damage to the electricity network following an electrical storm last night.' The failure mode of a substation could be quite interesting when the smoke comes out...
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