Hello,
the label on the power supply (hopefully) shown below says:
"Caution! Intended for installation in a protected environment."

What is meant by the word installation? Does it mean that the power supply must be mounted with screws using the fixtures on both sides of the unit or can it also be laid on the floor behind the machine it supplies (office printer)?

<img src="http://home.arcor.de/pengquadrat/PowerSupply-s.jpg" alt="Caution! Intended for installation in a protected environment.">

 
Likely "protected" means ‘away from moisture and temperature extremes,’ and “installation” in this case simply means ‘placement.’




[This message has been edited by Bjarney (edited 08-19-2004).]

That looks like it might be information technology equipment. If so, or even if not - many standards being similar, its components and insulation were probably evaluated for use in a pollution degree 2 environment (normal office environment). The manufacturer is being responsible in letting the consumer know this, even though it is common sense that an electrical device with vent holes is not suitable for a wet installation/use. This conformity magazine link (pdf file) covers pollution degree and the impact on product construction pretty well:
http://www.conformity.com/0111safety.pdf