NEC 800.90 requires protective devices on both ends of outside communications cables. Exception (3) indicates such protection is not required in an area with an average of five or fewer thunderstorm days per year and the earth resistivity is less than 100 ohm-meters. Where is such information available? (I have searched online but got no results.)
Communication Cable Protectors
- Thread starter PeteHJ
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cadpoint
Senior Member
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- Durham, NC
Good question!
Although this map is dated, (96’-2000)I believe this might give you some idea depending on your regional location.
This is a flash density map of the USA (96’-2000)
All based on a lightning strike map from my favorite search engine.
I looked at Ohm's measurement reading on the Web, but this goes in many directions, both in reference to radio waves and ground measurement of resistance, but I couldn't easily grab a USA map.
It seemed mostly to be instruments to measure either the earth or what’s happening in the atmosphere.
ohm measurement map USA; is what I was basing the second search on.
Hope this helps.
Although this map is dated, (96’-2000)I believe this might give you some idea depending on your regional location.
This is a flash density map of the USA (96’-2000)
All based on a lightning strike map from my favorite search engine.
I looked at Ohm's measurement reading on the Web, but this goes in many directions, both in reference to radio waves and ground measurement of resistance, but I couldn't easily grab a USA map.
It seemed mostly to be instruments to measure either the earth or what’s happening in the atmosphere.
ohm measurement map USA; is what I was basing the second search on.
Hope this helps.
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