Homeowner has Time Warner internet telephone cable direct to sub-building. Sub-building serviced by 4 wire 150A sub-panel fed from main 200A panel 100 feet away with ground rods located (1) at the main panel and (2) at the sub-panel, both bonded back to their respective ground bus. The sub-building has gas heat so the CSST pipe is bonded to the ground rod (for convenience) vs being bonded inside the panel. Can the internet cable be bonded to the same rod which would then make a loop of the internet cable directly from the sub-panel (via the cable) to the pole? Isn’t this likely to be current surge problem for the internet cable fed devices.

More grounding is better in a surge situation. You want a single point ground on your side of the building entrance, preferably right where the main bonding jumper connects to the grounding electrode conductor (same bus bar). That should be where the inter system grounding bus lands. Any "loop" created on the line side is your phone company's problem and they are well prepared to deal with it. They reground their stuff at every drop.

Thanks, Greg.