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I have a new project for a bank that is installing a new network rack in the branch. The Service for this facility is 400 amps. However, the architecture drawing showing the Telephone Bonding Backbone (TBB) is to be sized according to the following statement.
Green insulated copper conductor, minimum size of No. 6 AWG. The TBB
shall be sized at 2 kcmil per linear foot of conductor length up to a maximum
size of 3/0 AWG.
For this location the TBB run is 80'. That's a 3/0 copper TBB from the electrical room to the Tel/Data closet. That bonding wire is larger than the ground for the service and the size of an equipment ground for a 1200 amp circuit.
All this for a half rack of network equipment.
 

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Hackenschmidt
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It sounds like the architect lifted the spec from the TIA 607 standard. The idea isn't that the ground have the ampacity for safety like it is with electrical power, it is for low impedance for surge protection and uniform ground potential and all that jazz for trouble free communications and to protect the sensitive electronics.

For all the trouble and expense, I have seen more than one of these installed at small sites where nobody ever knows enough or bothers to bond the racks etc. to the TBB - sits there bare :)
 
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