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#147709 - 01/10/03 04:18 AM Video Clip of Serious Crane Accident!
Joe Tedesco Offline
Member
Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
http://www.themeterguy.com/photogallery/NewPics/Index.htm

See the clip showing the crane short!
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Joe Tedesco, NEC Consultant
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#147710 - 01/10/03 08:49 AM Re: Video Clip of Serious Crane Accident!
Redsy Offline
Member
Registered: 03/28/01
Posts: 2056
Loc: Bucks County PA
Damn! I hope nobody was hurt.
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#147711 - 01/10/03 11:43 AM Re: Video Clip of Serious Crane Accident!
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Joe, are you referring to this link?
http://www.themeterguy.com/photogallery/BoomTruckinPowerLines.wmv {Windows Media}

It's an extra-bad Monday waiting to happen again all over.
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#147712 - 01/10/03 02:23 PM Re: Video Clip of Serious Crane Accident!
golf junkie Offline
Member
Registered: 04/22/01
Posts: 507
Loc: York, NE
That's some wild stuff!

GJ
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#147713 - 01/10/03 03:59 PM Re: Video Clip of Serious Crane Accident!
Electricmanscott Offline
Member
Registered: 01/12/02
Posts: 1457
Loc: Holden, MA USA
WOW!!
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#147714 - 01/10/03 04:07 PM Re: Video Clip of Serious Crane Accident!
Trainwire Offline
Member
Registered: 03/15/02
Posts: 360
Loc: Strasburg,PA,USA
Hello? Boss?

Um, about the truck.

I think I will need a ride home.

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#147715 - 01/10/03 10:27 PM Re: Video Clip of Serious Crane Accident!
Format_C: Offline
Member
Registered: 08/14/02
Posts: 29
Loc: Bridgeport, Connecticut, USA
Shouldnt an OCPD prevented all of that?
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#147716 - 01/12/03 11:51 AM Re: Video Clip of Serious Crane Accident!
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
As for overcurrent protection, medium-voltage utility-type overcurrent protection is a different breed compared to that of typical low-voltage circuits and equipment. For one, sometimes ground-fault/earth-return currents can be below the settings or ratings of overcurrent devices. This may indeed result in flaming tires on incompetently controlled sign trucks.

This is in opposition to how we usually think of equipment grounding and bonding. Besides low current, it is very likely that the potential differences between the crane and the ground mat at a remote source will be large enough to seriously shock or electrocute those standing on the ground in the vicinity of the fault, though not touching any conductive surface short of your shoes contacting the surrounding earth. The rules are different, but in most cases well understood by folks routinely working in medium-voltage applications in utility settings.
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