On Wed, May 24, 2006 at 10:33:13AM +0100, Michael Rigby-Jones wrote:
> 
> 
> >-----Original Message-----
> >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
> >Sent: 24 May 2006 00:03
> >To: Microcontroller discussion list - Public.
> >Subject: [OT:] Kerzzap! Hope you had a good surge protector!
> >
> >
> >In my area, recently, there was a power surge of epic 
> >proportions. Someone knocked a transmission line into a 
> >distribution line.  The distribution grid (usually 12kV) took 
> >60kV for a few moments until the safties kicked in, resulting 
> >in 600V being delivered to 120V circuits for a few moments.  
> >But those few moments were enough to toast many appliances.
> >
> >Most people lost any electronics they had connected through 
> >surge protectors.  They're not rated to take that kind of a beating.
> >
> >http://www.thenownews.com/issues06/052106/news/052106nn4.html
> 
> "It's a really unfortunate situation for our customers," Moreno said. "We're certainly not expecting vehicles to run into our equipment on the road."
> 
> Surely any "street furniture" which would include power lines etc. should be designed and placed with this exact scenario in mind?

I remember talking to some linemen a few years back, they were fixing a
pole that had been cracked by a minor car crash. Amoung other things
they said that as much as possible the layout of lines is done to
prevent such a thing, but with the huge upgrades that have been done in
many areas to support air conditioners amoung other things it's really
difficult to keep lines seperated. There just isn't enough room often.

One thing that probably helps is lines can be insulated these days. The
overhead lines near my studio were replaced a few years back. It's
residential downtown toronto with massive trees lining the streets and
both the distribution grid lines and the feeders to houses are all
plastic insulated. Still, that costs a tonne of money I'm sure. It's
thick plastic, hard to tell for sure on the ground, but I'll guess it's
a 1cm thick conductor with mayby 2-3cm of insulation.

Somewhat related I've heard in Florida there is (was?) quite a bit of
study and debate done to decide if they would make some fairly massive
redesigns of the way they build their power network. The idea was to
hurricane proof everything, put lines underground etc. The power
distribution companies are getting tired of rushing out to fix lines
everywhere everytime a storm hits. 

-- 
pete@petertodd.ca http://www.petertodd.ca
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