Lightning damage or not?

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Coppersmith

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
I was investigating a lightning strike today. Parts of the system definitely looked burned, but other parts had no burn marks at all. Look at the 1/2" PVC in the picture. The conduit is totally destroyed, but there is no damage to the wires inside. I'm trying to understand how this might have happened. At first I thought this damage was caused by smashing the pipe with a cart or something, but all the conduit underneath the dock looks the same way. The HO told me he found the cover for the 8x8 box about 20 feet away.
 

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Daniel malack said:
When I have a customer that had a lightning strike I investigate this grounding system. Always find things wrong.

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Proper grounding system installation is not a definite factor on whether you will ever have a lightning strike enter a premises electrical system.
 
ggunn said:
Lightning does weird stuff sometimes.
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Well the "boom" you get with lighting is actually the air coming back into the vacuum left by the ionized plasma. It's going to create a shock wave, just like setting off an explosive charge nearby. I wouldn't be surprised if that shattered the PVC.
 
i was trying to find detailed historical strike data for Tampa but cannot seem to find any easily. but that area does seem to get many strikes
http://en.blitzortung.org/historical_maps.php
damage can vary based on the classification of the lightning, different types create different types of damage.
 
PVC conduit can degrade in the sun, depending on the quality. It's possible that it degraded and/or was crushed by something. Perhaps it was degraded and something about the lighting strike blew apart the weakened wall of it. Perhaps from an air pressure wave caused by the strike but not the lightning current itself? That might also explain the box lid, especially if there were no screws holding it on.

Just speculating here.
 
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