What you describe as describe as "all SPSes include at least
as much separate surge protection on the mains supply line as
a decent standalone surge protector would provide;" is really
near zero protection for numerous reasons. Both the plug-in
UPS and power strip protector have the same protector
circuit. And both are typically so grossly undersized to be
ineffective. Always start with the numbers. In this case
joules.

In another post and in those previously cited posts are
examples of how joules define protection. Notice that so many
plug-in protectors AND their plug-in UPS counterparts may be
rated at 345 joules. As joules increase, the life expectancy
of that protector increases exponentially. IOW if the plug-in
protector is good for two same size surges, then the 1000
joule 'whole house' protector is good for something on the
order of 300 of those same size surges.

Then it continues farther. The plug-in protector has no
earth ground. Therefore the manufacturer avoids the entire
topic altogether. This is how one identified ineffective (and
grossly overpriced - yes grossly overpriced) plug-in
protectors. 1) No dedicated wire connection to earth ground
AND 2) manufacturer avoids all discussion about earthing.

Further details will be provided in response to Milleron.
But the plug-in protectors are on the order of 10 and 50 times
more expensive per protected appliance. So yes, what you are
calling cheap protectors are really overpriced and expensive
protectors that also are not effective.

BTW, UPSes switch in milliseconds. (One must be careful to
buy power supplies with numerical specs that read: Hold up
time, full load: 16ms. typical). Surges do their damage and
are done in microseconds. 300 consecutive surges could pass
through a UPS before the UPS even considered switching to
battery power. Plug-in UPSes have one function - data
protection. They do not provide the hardware protection so
often implied.

You want a UPS that also provides hardware protection? That
is typically the building wide UPS that also makes this all so
important 'less than 10 foot' connection to earth ground.
Plug-in UPSes are for data protection; not for hardware
protection.

"Peter R. Fletcher" wrote:
On Sun, 09 Jan 2005 19:50:06 -0500, (Paul) wrote:
......
wiring exposure to just the power lines. A real ($1K purchase
price) UPS would reduce the risk of an AC power event from
getting you, and would help protect the PSU from getting
damaged. Cheap UPSes offer no protection at all, as they are
actually SPS (standby power supplies) - they are a "straight wire"
to power spikes, and the unit only cuts over to batteries if
the AC power dies for enough milliseconds.

I think that you are being unduly negative about cheap "UPSes". You
are absolutely correct that they are not true UPSes, since:
a) they normally connect the mains power (effectively) straight
through to the controlled devices, thus offering no _intrinsic_
protection from spikes; and
b) they have to switch to inverter mode when the power fails, which
takes finite time.
However:
a) almost all SPSes include at least as much separate surge protection
on the mains supply line as a decent standalone surge protector would
provide; and
b) All except the cheapest, no-name, ones switch fast enough so that a
normal computer system power supply does not "notice" the transient
power loss (though network switches, hubs, and the like may "glitch").
For most home and SOHO users, an SPS will provide cost-effective
protection against most of the data loss problems which might
otherwise be caused by brownouts and/or power outages, while their
built in (but unrelated) surge protection circuitry is a _lot_ better
than nothing as insurance against damage from power line spikes.

Please respond to the Newsgroup, so that others may benefit from the exchange.
Peter R. Fletcher