Permissible to bond communications circuits to sub-panel?

[PetesGuide]

I've got an installation in a commercial building (in California, built in 1955 and remodeled in 2001) that has evolved over the years with TV, satellite TV, and telephone connections all coming into an electrical room with both a main service panel (underground utilities) and a sub-panel.

The telephone line enters the building in a location that prevents connecting it to an IBT on or near the main service panel OR an additional ground rod without exceeding 20 feet. But the sub-panel is 3 feet away, and is connected to the main via underground conduit.

Would installing an intersystem bonding terminal on the sub-panel be both an effective and code-compliant means of bonding the telephone and nearby tV coax cables to ground?

If not, what's my best option--the >20 foot run to an IBT at the main panel?

 

[tom baker]

The requirement for the IS bond is to be connected to the building electrical GES, this is important to create a single point ground. The requirement in 250.94 is bonding at the service
There is an exception in 250.94 for existing buildings., and take a look at that

 

[ceb58]

At a communications site, there
shall be only one grounding (earthing) electrode system. For example,
the AC power system ground, communications tower ground, lightning protection system ground,
telephone system ground, exposed structural building steel, underground metallic piping, and any other
existing grounding system
shall be bonded together to form a single grounding electrode system.
Underground metallic piping systems typically include water service, well castings located within 7.6 m
(25 ft.) of the structure, gas piping, underground conduits, and underground liquefied petroleum gas
piping systems. (ANSI T1.313-2003; ANSI T1.333-2001; ANSI T1.334-2002; IEC 61024-1-2, section
2.4.4; IEEE STD 1100-1999; NFPA 70-2005, Articles 250.58, 250.104, 250.106, 800.100, 810.21, and
820.100; and NFPA 780-2004, Section 4.14).
Interconnection to a gas line
shall be made on the customer's side of the meter (NFPA 780-2004,
Section 4.14.1.3). See Chapter 6, ?Power Sources? for additional information on grounding and
bonding requirements of power sources.
The objective of grounding and bonding system components to a single point is to minimize any
difference of potential that may develop between individual components within the system and within
the equipment site or area. To reach this objective a low-impedance internal single-point ground system
is required for all communication equipment, support equipment, power systems, and other items and
materials located within the building, shelter, room or area of the same building.
A
single point ground system is defined as a single point, typically a master ground bus bar (MGB),
within a shelter, equipment building or room, where all communications equipment, ancillary support
equipment, antenna transmission lines, surge protection devices (SPDs), and utility grounds are bonded.
The single point ground system must be effectively connected to a grounding electrode system as
described in this chapter and in Chapter 4, ?External Grounding (Earthing)?.

This is a section from Motorola's R-56 grounding for communication buildings and equipment