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#147709 - 01/10/03 08:18 AM Video Clip of Serious Crane Accident!  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
http://www.themeterguy.com/photogallery/NewPics/Index.htm

See the clip showing the crane short!


Joe Tedesco, NEC Consultant

Arc Flash PPE Clothing, LOTO & Insulated Tools

#147710 - 01/10/03 12:49 PM Re: Video Clip of Serious Crane Accident!  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Damn! I hope nobody was hurt.


#147711 - 01/10/03 03:43 PM Re: Video Clip of Serious Crane Accident!  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
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.


#147712 - 01/10/03 06:23 PM Re: Video Clip of Serious Crane Accident!  
golf junkie  Offline
Member
Joined: Apr 2001
Posts: 507
York, NE
That's some wild stuff!

GJ


#147713 - 01/10/03 07:59 PM Re: Video Clip of Serious Crane Accident!  
Electricmanscott  Offline
Member
Joined: Jan 2002
Posts: 1,457
Holden, MA USA
WOW!! [Linked Image]


#147714 - 01/10/03 08:07 PM Re: Video Clip of Serious Crane Accident!  
Trainwire  Offline
Member
Joined: Mar 2002
Posts: 360
Strasburg,PA,USA
Hello? Boss?

Um, about the truck.

I think I will need a ride home.

[Linked Image]


#147715 - 01/11/03 02:27 AM Re: Video Clip of Serious Crane Accident!  
Format_C:  Offline
Member
Joined: Aug 2002
Posts: 29
Bridgeport, Connecticut, USA
Shouldnt an OCPD prevented all of that?


#147716 - 01/12/03 03:51 PM Re: Video Clip of Serious Crane Accident!  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
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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