Telecomm bonding to steel

[Pdan]

I'm hoping someone has run across this issue.

ANSI-607 2011 (a bit old) figure 2, example of a large building, shows a bonding conductor between TGB and building steel. Although the BCT and its size are defined in 6.3.3, the size requirements of the bonding conductor to building steel is not covered in this document.

I googled about this and found multiple sites that reference this standard stating that a #6 should be used, not a minimum #6, but specifically a #6 (regardless of the TBB and GE size).

Does anyone know if the size of this conductor is provided in any version of this or any other standard?

Any guidance on this would be appreciated. Thanks,
Patrick

 

[dkidd]

This says 6 AWG Minimum.

 

[Pdan]

Thank you dkidd,
Does this imply that it should be sized the same way as the BCT? We are using 750kcmil for TBB, GE and BCT.

 

[dkidd]

As long as you meet 100 milliohms you should be good.


It is recommended that this test be performed in the following areas:
a) TMGB/TGB to the electrical ground in Distributors
b) TMGB/TGB to the building steel (if present)
c) TMGB to TGB
d) Building steel (if present) to the electrical ground.

In order for this test to be valid it must be done before the telecommunications equipment is installed
otherwise parallel paths may invalidate test results.
The recommended maximum value for resistance between any point in the telecommunications
bonding and grounding system and the building’s electrical grounding electrode system is
100 milliohms. In the case of long TBB and GE conductor runs, the resistance of the conductor must
be factored into the total resistance. For example 1 km of a No. 3/0 conductor has a resistance of
0.2028 ohms. (0.06180 ohms per 1000 ft).