[BVARC] Lightning
Robert Polinski
emdhouston at cebridge.net
Thu May 27 14:25:20 CDT 2021
Most lightning damage done in a house is due to a poor grounding system on
the AC service. All service panels should have at least 1 8ft ground rod
with a min of #6 ground wire going to the panel board. The size of this
conductor is dependent on the size of the service. In many cases, this
ground is missing, the clamp has rusted off, or is just making a poor
connection. In many areas, the copper thieves have cut the pole grounds,
making your rod the last defense before the surge hits your home. Ground
rods need to have an impedance of lest than 25 ohms, sometimes more than 1
rod is needed to get this. Warning, before you do any checking or service on
your grounding system, turn off your main breaker & test your ground wire
with a clamp on amp meter. If it indicates any current, it is a sign that
the power co. ground is bad & working on it could cause electrocution. Call
an electrician.
The second issue is the failure to bond all grounds together. Newer
electrical services are required by code to have a intersystem bonding
block. On this block it has terminals for bonding CATV phone & any other
systems to the service ground. You ham station grounding system MUST be
bonded (connected) to this system with a #6 ground wire. This is a NEC code
requirement and a must to prevent station damage & possibly a fire. If you
do not connect the 2 systems together, and a strike hits the power line, the
lightning will seek the lowest impedance path to ground. If your station
ground is lower than the service ground, it will pass thru your equipment to
find it. Bonding the ground together eliminates this problem. Robert KD5YVQ
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