Laser printer draws current in a spike, what for?

Scratch that -- outlets on a circuit aren't in series.

AGAIN!No need for UPSs in the 21st century.We had an udersized one in the computer lab, in our college, with the result when everuthing is on it "tripped" (also a small blackout).It's so silly as to power your refrigerator from a generator set.

-- Dimitris Tzortzakakis,Iraklion Crete,Greece major in electrical engineering freelance electrician dimtzort AT otenet DOT gr ? "~Dude17~" ?????? ??? ?????? news: snipped-for-privacy@posting.google.com...

This depends where you live. The quality and nature of problems varies enormously from one locality to another. Where I am in the UK, we experience momentary drop-outs enough to reboot PC's about once every 2 years, and power outages of an hour or more perhaps once every 10 years. This means rather few people will bother with a UPS or generator, but there are circumstances where this level of failure is unacceptable, so you will find them used sometimes. I used to work in a small rural village, where momentary drop-outs happened every couple of weeks, and we did use UPS's in that case. Eventually we complained to the supplier. They investigated and found a cable fault in the 11kV feeder to the village, after which the problem went away. Normally, they are very rare in the UK. (There are reasons to suspect this high quality/reliability electricity supply the UK has become used to over last ~50 years is likely to come to an end over the next 10 years though.)

I have installed computer equipment in several non-UK European cities, and it is my experience (10 years ago now) that many of their supplies were generally nowhere near as reliable as ours in the UK. Power outages of mintues to an hour were quite common, and then everything is on UPS's backed by generators. Momentary drop-outs were insignificant though.

Don't have as much experience of this in the US, but momentary drop-outs seemed to be a significant issue in several locations, enough to reboot systems sometimes, so UPS's are commonly used. Extended outages seem to be few and far between (except when the rolling power cuts were running in California).

There are places in the world where electricity is only provided for a certain number of hours per day, or even on an unpredictable basis. (And of course many places where there's none at all.)