How a fallen tree can make a house explode

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http://seattletimes.nwsource.com/html/localnews/2016337715_gasleakexplain28m.html?syndication=rss


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When an electrical surge hits ground near buried pipelines, the hungry current, seeking the least-resistant path, sometimes finds its way to the conductive carbon steel of these lines. Electricity races along the pipe and rips tiny holes or heats up and softens the line itself in spots, leaving the pressure of the line's contents to blow it out.

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That's what Puget Sound Energy's internal investigators now say they believe happened when a North Seattle home blew up Monday morning, injuring two occupants.

They maintain that a windstorm on Sunday blew a tree into a power line near 127th Street Northeast and 12th Avenue Northeast, and a surge of electricity somehow reached PSE's pipeline. They believe that surge caused several leaks, including one that filled the home with gas. A spark ignited the home Monday morning.

PSE officials say they've found at least four BB- to finger-sized holes in the neighborhood gas lines that appeared to be caused by an electrical surge, PSE spokesman Martha Monfried said.

-long snip of saying its arcing that's the reason and giving examples-
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however:

And while Seattle City Light acknowledges a tree did strike a power line Sunday morning, it maintains the incident immediately tripped breakers, and the nearest utility poles have grounding wires. The system is designed to quickly ground out shorts, so it's not clear what pathway the electricity would have taken to the pipeline.

"I can't speculate on what might have transpired," said City Light spokesman Scott Thomsen. "But our equipment worked as designed."
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think I'll go with City Light

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1. kicking back to pg. one

nt