The HowStuffWorks article that was linked does a pretty good job of explaining how surge protection works in layman's terms. It is talking about the lower end of available surge protection, and I suspect the article is a couple of years old.
Two types of protectors exist. Protectors that connect surges harmlessly to earth - energy not inside the building. That protect from the few surges that cause damage - ie direct lightning strikes. Another is a $3 power strip with ten cent protector parts selling for $25 or $150 - a profit center.
Posted back in Aug 2002 is a description of that HowStuffWorks article that was even removed as a citation in Wikipedia for being bogus.
From HowStuffWorks:
> A more common cause of power surges is the operation of high-power
> electrical devices, such as elevators, air conditioners and refrigerators.
If refrigerators and air conditioners were creating destructive
surges, then all would be trooping daily to hardware stores to replace
damaged dimmer switches, electronic timers switches, X-10 remote
controllers, and touch on-off lamps. Surges created by refrigerators,
et al are urban myth because you don't replace those other appliances
daily.
Furthermore if refrigerators, et al created those surges, then surge protectors must be installed in those surge creating appliances - not on every other appliance.
If refrigerators created those voltages in excess of 330 volts (as clearly listed on surge protector boxes), then we must remove those appliances as a threat to human life. We don't remove those appliances because they don't create 'urban myth' surges.
MOVs have limited life expectancy as defined by joules. If refrigerators and air conditioners were creating destructive surges, then those plug-in surge protectors would be degraded in weeks or months without any indication of failure. What good is a $50 surge protector that must be replaced every month? Ineffective.
In summary, HowStuffWorks on surge protectors has numerous technical errors. It begins accurately, but then makes serious errors. It preaches what plug-in surge protectors promote rather than the principles of surge protection proven in the 1930s. The author probably did not have sufficient knowledge to see through half truths of his information source - plug-in protector manufacturers. Therefore HowStuffWorks is riddled with errors and misrepresentations.
Because plug-in surge protectors don't claim protection from direct lightning strikes, then instead HowStuffWorks claims most surge damage comes from refrigerators, et al. But we have demonstrated that such surges don't exist. In reality, lightning is the most common source of surge damage - in direct contradiction to plug-in manufacturer claims and to text in HowStuffWorks.
UPS protectors parts are as tiny as possible. Near zero joules. Just barely above zero so that a majority can be told it does 100% surge protection. All appliances already contain major protection. Only rare surges overwhelm that protection. If it does not protect from lightning, then it is protecting only from something that typically causes no damage.
UPS has only one function. Provide temporary (and 'dirty') power during a blackout.
