Reducing mains voltage to 220V to cut bills...

[Panrock]

I recall in the '60s my dad had some 275 watt reflector lamps to allow indoor shooting on Kodachrome II (25 ASA) standard-8 movie film. These were intentionally overrun to improve the blue output, and I believe they were supposed to last about 2 hours.

[ppppenguin]

I've got some 275W photofloods somewhere. They look like an ordinary 60W bulb and if you run them at 110V that's roughly how they behave. It was, I think, common to have series/parallel switching for photofloods so you did all your set up with them in series and switched to parallel to get the shot. 2 or 3 hours is about right for them at full power.

This explains the gas/vac tradeoffs very well: http://www.lamptech.co.uk/Documents/IN%20Vac-Gas.htm A lot is to do with heat loss which is low with a vacuum compared to gas filled. It also says that outdoor festoon bulbs were often vacuum to keep the glass temperature down and reduce risk of fracture in rain.

[colly0410]

Where my wife does her line dance classes they have two new electric kettles that claim to be 72% more efficient than normal kettles. AFAIK all electric kettles are very near 100% efficient so how they make this claim I don't know. Hope they didn't pay a lot extra for the 72%....

[PerdioPal]

Fudging figures...  Say kettle 95% efficient, 72% of the 5% left is 3.6%.

[Mike Watterson]

I was thinking that for many things going from 220V to 240V is more efficient?
Anything with a regulated SMPSU takes less current, so less loss in house wiring.
A kettle or toaster or grill is more efficient if it's hotter and boils / browns faster?

[PerdioPal]

" so less loss in house wiring." Exactly why we have 132+ kV pylons, a 132kV toaster would make for very quick toast!

[Doodlebug]

When doing cine work I had two photo floods in series to give enough light to set up the scene. Then when ready to shoot
both floods were connected straight to the mains. This also had the advantage of less thermal shock as they were already hot.

[Mike Watterson]

" so less loss in house wiring." Exactly why we have 132+ kV pylons, a 132kV toaster would make for very quick toast!

I think 10 kV would be more practical for the wiring insulation?