Lights dim every day at the same time

[btb23]

I've often wondered what might have been the cause of this and thought here would be a good place to ask. In the previous area I lived, at 3 minutes past 1 every morning (01:03), the lights would dim. Nothing in the house came on at that time. It went on for over 20 years that I noticed, at two different address's in the south Notts area. We now have energy saving bulbs and I'm not aware of it happening where I currently live.

I thought it might have been down to the supplier reducing the capacity available overnight, does that kind of thing happen? Just curious.

 

[flameport]

Probably some heavy load switching on in the area, such as storage heaters. The actual voltage drop is probably small, as it only takes a small reduction to cause a significant change in the brightness of incandescent lamps.

The other possibility is some heavy load is switched off at that time, which would cause the voltage to increase, and the transformers supplying your area automatically compensate by reducing the voltage, but the adjustment is slightly more than required so overall, the voltage drops slightly.

 

[mikhailfaradayski]

seem likely that the low rate contactors pull in at around that time.
If all your neighbours have storage heating etc, then they would all come on at the same time, possibly causing the local voltage to pull down a bit.

 

[Taylortwocities]

I don't suppose that your neigbour is called Dr Frankenstein??

 

[stargazer]

Is that equipment 3 phase?

 

[ban-all-sheds]

Is he demonstrating to Igor the sequence:

1. Test for dead
2. Switch on
3. Test for live

?

 

[stargazer]

4. Test for life

 

[ban-all-sheds]

That's what I meant....

 

[Steve]

I thought it might have been down to the supplier reducing the capacity available overnight, does that kind of thing happen? Just curious.

At night a lot of "wierd and wonderful" things happen on the electricity network.

I'm not sure how true it is, but at school when we learnt about renewable power in geography, we talked about water power. Apparently during the day, water flows the "normal" way, downhill with gravity, and is driving the propellors and generating. At night, there is extra capacity on the network, since everybodys in bed. So they take advantage of this and drive the water back uphill, using the turbines as motors.

The spare capacity at night is where e7 came from. Between midnight and 7am, the network is at its lowest consumption, so they sell the electric cheaper then to increase demand. Then they developed storage heaters to take advantage of this, and various switching methods to engage low-peak circuits in homes. These include a harmonic frequency superimposed onto the 50HZ AC cycle, which the teleswitch can pick up, as well as radio teleswitches and timeclocks.

So in short, a lot happens at night to take advantage of the spare power on the grid. And a lot of people, including businesses take advantage of it. The spare capacity is there because fossil fuel power stations simply cannot shut down overnight.

 

[Click-Sure]

The E7 switch-on is controlled by a signal sent out on the LW frequency that BBC radio 4 uses, not a signal superimpoed on the line frequency.

The water power thing only works with specialised stations, dinorwig being the plant in question, think there is another one now.

 

[efiste2]

If its common to a lot of local properties it could be a local factory turning on a heavy current device. Years ago large areas of Crewe use to experience a dip at the same time every day as the local steel works turned on its arc furnace.....Or as load drops at night the primary substation transformers tend to (as flameport mentions) TAP down and reduce the High Voltage slightly. But i wouldnt expect it to be the same time every night!!!

 

[timtheenchanter]

At night a lot of "wierd and wonderful" things happen on the electricity network.

I'm not sure how true it is, but at school when we learnt about renewable power in geography, we talked about water power. Apparently during the day, water flows the "normal" way, downhill with gravity, and is driving the propellors and generating. At night, there is extra capacity on the network, since everybodys in bed. So they take advantage of this and drive the water back uphill, using the turbines as motors.

indeed it is true, you can even go have a look round it if you want http://www.fhc.co.uk/electric_mountain.htm

its fantastic, I dont know if it still is, becuasde its about 9 years since i went round it, it was the only one of its kind in the world

 

[ban-all-sheds]

1) There are 3 others in the UK. Dinorwig is the largest.

2) Even when it was built it wasn't the only one of its kind, let alone 9 years ago. http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

 

[timtheenchanter]

I stand corrected, I could have sworn the bloke showing us around said it was the only one, either I mis remembered (it was a while ago) or it was a PR spin!

 

[bernardgreen]

The company I worked for at the time supplied and installed equipment during the building of Dinorwig station. A colleague drove a car along the inside of some of the water pipes feeding the turbines. I believe vehicle access to the pipes is still possible to facilitate maintainance work.

Definately a time to ensure the taps are turned off and locked off during while working.