Home Power Usage
Home Lighting

The first question was:- what do my house lights ACTUALLY use

By rejigging the wiring of the consumer unit (only do this if you know what you're doing), I got the sensor monitoring the lighting circuit only. The idea was to turn one household light on, let the current settle, note the power being drawn, check it hasn't changed after 5 minutes and then turn it off.

It was a good plan until I looked at the monitor with all the lights off... There was power being used. I went round the house double checking and found the porch light switch on. The light was off, but it has a dusk sensor, so had to be using some power (very little) to power the sensing circuit. That reminded me I had a security light in the back garden that also had a dusk sensor. Turned these both off and there was still some power being drawn somewhere. After some head scratching and trips around the house, eventually found a TV arial booster in the loft being powered by the lighting circuit. So, turned that off and went and checked the power monitor again - Zero.

So, step one, set everything up to do the tests took two hours more that the 15 minutes expected to do this bit of work. The rest went a little bit more as planned. Turned something on, waited a minute, took a reading, re-took it 5 minutes later then turned it off. With the two sensor lights, took a reading while on but during 'daylight' and another by covering the sensor so the light came on. On the chart below, the porch light is shown twice, standby and on, the rear security light is only showing the 'light on' bit. I actually did these checks in June 2010 so can't find the missing bits of data (rear security light in standby).


The results of the test

If you're wondering about the colouring of the bars, there is some madness to my method. Starting with 'pink'. These lights are on dimmers (hence full and half - which is a guess) so are conventional bulbs and not used very often. We have side lights which plug into the 13A wall sockets which we mainly use.
The 'red' are 50W spots which I haven't got round to replacing with a low energy equivalent. But because the rooms are used a lot, they are a high power consumer.
Jumping to the 'green' coloured lines, these are lights that are left on with no one around although the porch and landing lights are usually turned of when the family has hit the sack.
The bulk of the bars left are mauve(?) and are either dimmers not used that much or low energy.
And that leaves the 'yellow'. The porch on standby (which is some of the time), presumebly the rear security light every day and last but by no means least (and probably the one worth mentioning the most) is the TV signal booster at a massive 9W.