Daily Archives: 23rd June

The Half-Time Kettle Effect quantified

The Half-Time Kettle Effect (HTKE) is an oft-reported part of the football season. The idea is very simple: at half-time, a large number of people watching the match will make themselves a cup of tea, using an electric kettle to do so. The HTKE is the resulting “spike” in the demand for electricity that this causes.

The National Grid is kind enough to make realtime demand data available at their website, so I decided to see what happened during the England-Slovenia game today.

Unfortunately the actual numerical data isn’t available yet via the National Grid website, so I’ve had to calculate the data from the graph itself; data is only updated once every five minutes, so that’s also less than ideal.

From the start of half-time at 1545 to peak consumption ten minutes later at 1555 demand jumped by 1235 megawatts to 40314 megawatts, a 3.2% jump. This is equivalent to more than six hundred thousand average (2 kW) kettles, or an average-sized coal or nuclear power station.

Chances are that the spike isn’t due to kettles alone; opening the fridge door for a beer will often cause the compressor to kick in to replace the lost cold air. Microwaving food or turning on the light to go to the toilet are probably also major contributors to the HTKE.

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The problem with the bulb ban

You might not have noticed, but the sale of standard filament lightbulbs has been banned since last September.*

Current proposals are to replace standard incandescent bulbs with more efficient compact fluorescent bulbs. Fluorescent lights work by passing a current through a tube containing mercury vapour. The excited mercury atoms emit ultraviolet photons which then collide with the phosphor coating on the inside of the tube, causing it to emit light (to “fluoresce”) in the visible part of the spectrum.

The problem with this is that some of the ultraviolet light is still emitted (in fact germicidal lamps are basically fluorescent bulbs without the phosphor coating). Many people are sensitive to ultraviolet light and cannot enter rooms lit by flourescent lamps.

People with conditions such as photodermatosis (where exposure to ultraviolet causes swelling, rashes and blistering) and people with photosensitive epilepsy (the 50Hz mains supply flicker is visible from fluroescent bulbs but not from incandescent ones) have been stockpiling bulbs since the ban was announced.

I’m not against the sale of compact fluorescent lightbulbs; in fact I’d like to see them more widely used (especially in place of the inefficient halogen spotlights that seem so popular). What I’m against is removing the consumer’s right to choose.

(If you’re desperate for lightbulbs and you’re wondering, I took the photo above outside of Rugby Electrical, in Rugby.)

* Technically, it’s only the sale of bulbs for household use that’s banned. “Industrial use” is still okay.