On Friday, May 20, 2016 at 4:18:54 AM UTC-4, westom wrote:
On Thursday, May 19, 2016 at 5:22:29 PM UTC-4, Uncle Monster wrote:
When I was a kid growing up on the family farm on the mountaintop in Northeast Alabamastan, lightning was a constant menace. I remember being in the basement of the house when I would hear an arc jump from the metal heating duct that ran the length of the house to one of the 6" steel poles supporting the center beams that ran down the center of the house. I could often count more than 10 seconds before I heard thunder.

Your example demonstrates why underground wires are just as exposed to lightning. Ten second delay means that lightning struck earth some 2 miles


It demonstrates nothing of the sort. An overhead service running into
a house provides an additional target in very close proximity to the
house. Clearly a strike on that line, close to where it enters the house,
presents the potential for a larger, more destructive surge than
lightning that strikes two miles away.




away. That current traveled through earth, then through more conductive materials inside the house (resulting in an arc), and then back into earth to travel maybe more miles to earthborne charges.

How did it get into the house? Maybe buried wires. Maybe an underground pipe. But we know this. It got into the house by connecting to earth some 2 miles distant.

How many volts and joules do you think you see at the panel from that
2 mile away strike, versus one at the masthead?

Next!