On 10/29/2018 8:08 PM, Wayne Burdick wrote:
Many of us remember to disconnect antennas when lightning is anticipated. But in our experience, the most common source of damage, by far, is from an attached computer. Computers themselves often fail due to lightning strikes. They can also act as conduits for surges to other gear. Just to emphasize this point: Customers often say "I disconnected everything but the USB cable to the computer...," which left the interface to their radio exposed.
Don't blame the computer -- it's the MOV "surge protector" that the computer is plugged into. As hams, we're fixated on antennas as entry points for lightning, but power lines, telephone lines, and CATV lines are more common entry points, and the DIFFERENTIAL voltages during a strike between interconnected equipment fries them. Several pro audio engineering colleagues who were not hams experienced damage to their networked computers from lightning strikes, and it was an issue with the large audio systems we designed for worship and performance venues. The solution is a SERIES MODE surge protector that stores the energy from a strike in an inductor, then discharges it slowly. MOVs shove the strike current onto the green wire back to the panel and ground rod, generating the differential voltage that fries equipment.
Several rules. 1) Proper BONDING is FAR more important that bigger ground conductors. 2) NEVER use MOV surge protectors -- they are far more likely to CAUSE equipment destruction than to prevent it. 3) Follow NEC (the National Electric Code) for grounding and bonding.
N0AX's recent ARRL book on Grounding and Bonding is excellent. I worked with him on it, and much of it is based on my tutorial talk on the topic.
http://k9yc.com/GroundingAndAudio.pdf 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
