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Re: Ballast life

Gross oversimplification.  Of COURSE engineers try to design and build safety 
factors into their equipment, and try to use over-rated components so that 
they will always be operating well within their limits.  (I know this because 
I used to be an electronics design engineer.)  But then here come the bean 
counters, and this component is downgraded from a 400v rating to a 200v, and 
that component is downgraded from 1 watt to 1/2 watt, etc.  Bottom line is, 
they try to build it good, but they also have to keep it price competitive.  
And there is no such thing as the "perfect" component.  Anything can fail.  
Tires can go flat the day you buy them.  Transmissions can fail 3 days after 
you buy a car.  Space shuttles can blow up on launch.  Most will not, but 
there will always be exceptions.  If it's going to fail, it usually does so 
early in its life, which is why they make manufacturers' warranties.  If a 
manufacturer makes 1000 widgets, he knows that a certain number of them will 
last forever, but a certain number of them will also fail in the first week.  
Your assignment: figure out which one you got when you bought it.  To make 
something that is 100.000% guaranteed to last a year, or 10 years, or 
whatever is an impossibility.  There will ALWAYS be a few failures.  All I 
did was just list things you can do to have some control over that.  Don't 
run it overvoltage, and keep it cool.  And then there are always nearby 
lightning strikes, which can melt down any electronic device, no matter how 
well protected.  
> Well yes and know.  The components, if used properly,
> usually have average lifespans, safe operating areas, etc,
> MTBFs and other ratings that can give a manufacturer an
> idea about how long its devices might last.  That, testing,
> and experience allow for some good estiamtes of expected
> life.  If a ballast designer has no idea whether the
> ballast will last longer than a year when used in a
> reasonably normal way, then he ought to to quit the biz.

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