Date: 20010531 From: w_tom Newsgroups: sci.electronics.misc Subject: Re: Surge Protector or UPS with Surge outlets? Lighting strikes! 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. 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.