here is a post i found on google groups
From: w_tom (
[email protected])
Subject: Re: Surge Protector or UPS with Surge outlets? Lighting strikes!
Newsgroups: sci.electronics.misc
For starters, read the thread entitled "UPS Question" about 7 May in this
newsgroup (sci.electronics.misc).
What does a surge seek? Earth ground. Effective surge protection, proven
since the 1930s, shunts to earth ground before a surge can enter the
building. Surge protectors (such as the battery backup power supply) only
shunt (short or divert) a surge from one wire to all others. If connected
less than 10 feet to a good earth ground, then a surge is safely shunted to
earth. But ineffective surge protectors don't have that critical earth
ground connection AND are too close to the appliance. Instead of a surge
seeking earth ground through an adjacent appliance via one wire - now with an
adjacent surge protector, the surge seeks earth ground on all wires -
destructively. Ineffective surge protection located too far from earth
ground and too close to transistors.
A surge protector is only as good as its earth ground. Shunt to earth
ground before the surge gets near a system. 'Whole house' surge protection
for residential electric is available from Home Depot for less than $50 - or
about $1 per effectively protected appliance.
Joules: if sufficiently sized, then joules are a ballpark measurement of
surge protector life expectancy. If a plug-in surge protector (UPS or power
strip), then derate by 1/3rd. IOW a 345 joule plug-in surge protector is
considered only 115 joules. For every doubling of joules ratings, expect
surge protector life expectancy to increase by no more than 10 times. IOW a
properly sized 1000 joule surge protector will last no more than 1000 times
longer than the rated 345 joule / actual 115 joule plug-in surge protector.
Plug-in power strip and UPS surge protectrors have the same surge protection
circuits. Ineffective surge protection is frequently identified by two
features - no dedicated connected to an earth ground less than 10 feet away
AND no mention of critical earth ground. That characterizes plug-in surge
protection.
Adjacent plug-in surge protection can actually complete a surge circuit
that damages the powered off computer. Surge protectors only shunt (short or
divert) a surge from one wire to all others. They don't stop, absorb, or halt
a surge. If connected less than 10 feet to central earth ground, then the
surge is shunted to earth ground. However if far from earth ground and close
to a computer, then the plug-in surge protector has provided more paths for a
surge to get inside and destroy the computer. Effective surge protection is
located close to earth ground and far from the protected transistors.
Telephones typically have effective surge protection. Telcos install
'whole house' surge protection on phone lines at the premise interface. But
some forget how electricity works. Like a fuse, a damaged transistor is the
weakest link in the circuit. Lightning did not come in on phone lines,
destroy the modem, and stop. Lightning is electricity. It must have an
incoming and outgoing path. Typically the incoming path is AC electric;
outgoing is the phone line earth ground. A modem is damaged because it was
the weakest link in a path from AC electric to phone line earth ground. The
modem was damaged because a surge was not shunted to earth ground where the AC
electric entered the building - no 'whole house' surge protection was
installed.
jay wrote:
> Have recently had a lightning hit to the local area, took out 2 tv's, 1
> computer pwr supply, external modem. Similar happened to neighbours
> equipment.
>
> Now that the horse has bolted, I would like to protect what I can.
>
> For the Computer do I go for a 6way strip with surge protection, with
> telephone points on it, or do I go for a UPS with all of the above. The
> reason why I ask is, a friend of mine, said that a UPS would offer better
> protection.
>
> What Joule rating should I be looking for?
>
> As for the TV I was looking at a surge strip with co-axial outlets.
>
> The Belkin range of products do both the UPS and Surge strips, has any one
> had any experience with the what seems to be a rather excessive protection
> warranty that come with them. Something like £20,000 on items connected to
> the units.
>
> Thanks for any input.
>
> Sorry in advance if this has been thrashed out before.