Originally Posted by KG363
btw, how do you know so much about this?
Multiple decades of design experience. And designing systems that took direct lightning strikes without damage (and a few educational experiences where damage did occur). And learning from the so many others who did this stuff. For example, Polyphaser's app notes are highly regarded in the industry:
US Air Force Instruction 32-1065
> 15. Surge Protection.
> 15.1. Entering or exiting metallic power, intrusion detection, communication antenna,
> and instrumentation lines must have surge protection sized for lightning surges to reduce
> transient voltages to a harmless level. Install the surge protection as soon as practical where
> the conductor enters the interior of the facility. Devices commonly used for this include metal oxide
> varistors, gas tube arresters, and transzorbs.
Planning guide for Sun Server room
> Section 6.4.7 Lightning Protection:
> Lightning surges cannot be stopped, but they can be diverted. The plans for the data center
> should be thoroughly reviewed to identify any paths for surge entry into the data center. Surge
> arrestors can be designed into the system to help mitigate the potential for lightning damage
> within the data center. These should divert the power of the surge by providing a path to
> ground for the surge energy.
To do this stuff, we had to learn this stuff including autopsies to discover why our designs failed. Any plug-in protector is nothing more than a profit center. Phrases such as 'divert', 'energy dissipation', and 'single point earth ground' are essential. How to identify a scam protector. 1) It has no dedicated wire for that always short (ie 'less than 10 foot') connection to earth ground. 2) Manufacturer avoids all discussion about earthing.
A case study on how damage to a radio station was eliminated. They used no plug-in protectors because a solution was needed. They only fixed what always provides protection - the earthing:
http://www.copper.org/applications/e.../nebraska.htmlEdited by westom - 6/8/10 at 11:22am