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## Re: what is the joule rating on surge protectors?

 Subject: Re: what is the joule rating on surge protectors? "w_tom" 12 Aug 2006 11:24:08 -0700 sci.electronics.basics
 ```John Larkin wrote: > If "earth" is zero volts and you dump, say, 10,000 amps into it, > what's its power dissipation? Earth is zero volts when a 10,000 amp current travels four miles to earthborne charges? Not true. When earth is conducting lightning, a four legged animal in that path may become a victim. A tree is struck. Shortest path to earthborne charges is down tree, through earth, up that cow's hind legs, down its fore legs, then on through miles of earth to earthborne charges. Why is the cow killed? If earth is zero volts, then electricity would never travel through and kill a less conductive cow. Earth is not zero volts because earth is not zero ohms. Earth is dissipating lightning energy. A cow's body makes a more conductive path; therefore cow is killed. Earth is so non-conductive that energy in those 10,000 amps is dissipated in many miles of earth and takes an electrically conductive path through cow. Earth is where energy is absorbed because earth is not a zero ohm conductor. Earth is not zero volts. Miles of earth is where energy from 10,000 amps is absorbed. Effective protection means a low impedance (as possible) shunt to earth so that little energy is absorbed by the shunt (MOV, GDT, avalanche diode, or lightning rod) and so that significant energy is absorbed by earth. A low impedance shunt does not absorb the energy just like wire does not absorb energy. Better protectors are even lower impedance when to provide even better protection. Shunt energy to earth where energy is absorbed. Franklin demonstrated same in 1752. Did his ligthning rods, instead, absorb the energy of a lightning strike? Of course not. Earth absorbs the energy. Just like MOVs, the lightning rod make a low impedance connection to earth. MOV joules is how life expectancy is measured. Just like wire, a 39 joule MOV absorbs little energy while shunting massive energy into earth. Unlike wire, the MOV eventually degrades with use. We measure this MOV life expectancy in joules. A more conductive and superior MOV absorbs less joules. Therefore a more conductive MOV will shunt more energy to earth, absorb less energy, and has a longer life expectancy. They are shunt mode protectors. To protect by absorbing energy, a protector would be a series mode device - in line with electronics. MOVs are not series mode devices. MOVs are shunt mode devices. MOVs are effective when energy is diverted to and absorbed by earth. If MOVs absorbed energy, then voltage on protected appliances must increase - completely undesireable. Effective MOVs make a low impedance connection to earth just like a switch. That means less voltage confronting protected appliances, less energy absorbed by the MOV, and more energy into earth. That means even better protection. Notice: better protection means even less energy absorbed by the MOV; more energy absorbed in earth. http://www.arcelect.com/lightnin.htm > Any lightning protection device must be composed of two > "subsystems," a switch which is essentially some type of > switching circuitry and a good ground connection-to allow > dissipation of the surge energy. The switch, of course, > dominates the design and the cost. Yet, the need for a good > ground connection can not be emphasized enough. > Computer equipment has been damaged by lightning, not > because of the absence of a protection device, but because > inadequate attention was paid to grounding the device properly. ```
 Current Thread Re: what is the joule rating on surge protectors?, John Fields Re: what is the joule rating on surge protectors?, John Larkin Re: what is the joule rating on surge protectors?, w_tom <= Re: what is the joule rating on surge protectors?, John Larkin Re: what is the joule rating on surge protectors?, John Fields Re: what is the joule rating on surge protectors?, John Larkin Re: what is the joule rating on surge protectors?, John Popelish Re: what is the joule rating on surge protectors?, John Larkin Re: what is the joule rating on surge protectors?, John Popelish Re: what is the joule rating on surge protectors?, John Larkin Re: what is the joule rating on surge protectors?, John Popelish Re: what is the joule rating on surge protectors?, Sjouke Burry Re: what is the joule rating on surge protectors?, John Popelish