Grounding for outside plant cables

[SWITCHDOG]

I'm doing a charity job (free) for a small museum. My scope of work is deploying an aerial RG-11 cable for data, and re-using an existing 12 pair aerial cable for voice.

For clarity, I would prefer to use fiber for the data, their finances force use of coax/HNPA adapter for the network

Both the coax and the voice cables have UL 497 Listed Primary Protection, grounding is 8' rods, 16 feet apart, grounding conductor is stranded #6 with a green jacket. Both protectors connect to an intersystem bonding termination.

Here's the issue: The building does not appear to have a grounding electrode system [250.50] for the electrical service as power is fed from another building by a 70 year old underground service.

Here's the question: Where does the IBT connect to to meet NEC 250.94 ?

 

[AndrewTech]

I'm betting you already have the answer but i would say setup a seperate grounding bar in the comm room and ground to that. Keep it separate of the electrical system to prevent power feedback and possible damage in the event of a power spike or short,

 

[SYQUEST]

You might also contact the AHJ, Authority Having Jurisdiction, or local inspector for guidance to make sure it is NEC compliant. It would not hurt to verify the integrity of the 70 year old service ground either. Things can get loose over time!

Hope this helps!
....JIM....