Re: protection

["w_tom" <w_tom1@xxxxxxx>]

Rich wrote:
> What type of lighting protection would you use on a 600 ft 25 pr under
> ground cable from school to a stadium?

  A protector is not protection.  A protector connects that wire to
protection.  Protection is earth ground.  A protector that does not
shunt a surge into earth is often promoted on word association:  "surge
protector = surge protection".  Sounding alike does not mean they are
same.

  An industry professional demonstrates the concept in an application
note.  Two structures.  Each has its own single point earth ground.
Any wire that interconnects both structures must be earthed where it
enters each structure.  If any of those 25 pair wires cannot be earthed
directly, then install a surge protector from each wire to earth
ground.

  This is how your telco - connected to overhead wires everywhere in
town - keeps their $multi-million computer working even during
thunderstorms.  Every wire that enters the building is connected to
earth as short as possible.  That protector is distant (up to 50
meters) from protected electronics.  That separation inside the
building means additional protection.

  Most critical is that the earthing be single point.  Every incoming
wire must earth to the same earth ground.  Each structure must have its
own single point earthing.  See the application note TN CR 002   The
Need for Coordinated Protection at:
http://www.erico.com/public/library/fep/technotes/tncr002.pdf