On 1/18/2021 9:09 AM, Bill Frantz wrote:
While serious lightning protection for structures and other robust
things must be done outside the building, I have heard reports of K3S
USB chips being fried from currents induced in the USB cable attached to
the radio, with the suggestion of disconnecting the cable to protect the
chip. I don't see how to do this disconnect outside the building.
Right. That is the kind of failure that proper grounding and bonding are
able to protect against. It's also the kind of destructive failure that
the use of MOV surge protectors can CAUSE.
When I consider a direct strike on my shack's lighting rods, I see
massive currents flowing down the thick aluminum cables from the rods to
the grounding system. I see these currents inducing currents in any
wires in the house, including the USB cable. The lightning rods are the
first level of protection, but may not be enough to protect sensitive
electronic equipment. Remember, when we work on these radios, we have a
grounding wrist strap and a conductive mat on the work surface etc.
That's another thing the proper grounding and bonding protect against.
But lightning induces current not only on that external wiring, but also
wiring within the building. IEEE studies show that up to 3kV can be
induced on internal wiring by a strike!
73, Jim K9YC
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