OK, we all know that the EC has to install that new intersystem ground block as per 250.94. Here comes the question,
Is the EC required to run a grounding conductor from this ground block to the Telco /CATV equipment? Or is the EC just required to install that ground block and then have the Telco/CATV people come back to install their own grounding conductor?
I think the Telco/Cable/Satt contractor should be running their own ground to your block. (it was the ground rod(s) back in the olden days) In most cases with cable, their box is sealed anyway. In my experience they are not very diligent when it comes to grounding so somebody does need to follow up and inspect this. Hopefully it has been done before the final electrical inspection but that may not happen. I used to warn homeowners of the problem and have them hold the installer's feet to the fire when they get their cable or phone installed. I offered to get in the middle if it came to it but I am guessing my card with a short note on the back was all it took because I never got a call back. My experience with lightning damage in the computer biz made me a fanatic about good grounding practices.
An EC who is a friend of mine said he failed a job because of that reason. So now he asks,"Is it my responsibility to connect the Telco grounding conductor? If so what code section does that fall under?"
If it is an existing building and the telco or CATV are already properly grounded and bonded, then 250.94 exception doesn't require the intersystem bonding termination to be installed, however you can install one at the service for other additional buildings if needed. It's a rare event that it's done correctly with the current requirements for size, length and connection location, etc, especially in older buildings, but sometimes you do see it. I guess they figure that if these systems are already properly bonded, then leave well enough alone.
I've noticed that around here, all of the telco ground wires have yellow tags on them at the point of connection that say "Warning, if this clamp or wire is loose or removed contact the telephone company repair service." This seems to indicate that they want ultimate responsibility of the grounding and bonding for their systems.
Re: Intersystem grounding block
#192965 03/12/1010:23 AM03/12/1010:23 AM
I agree that if the Telco system was bonded when the EC gets there, then after a service change, the EC should re hook up the Telco/CATV grounding conductor.
The question comes from the fact that the Telco equipment was on one side of the house (And on it's own separate grounding system) and the service replacement is on the other side of the house. Should the EC fail the inspection because the TELCO guy didn't ground his system from the very start of the building project?
I started out in this trade as a Burg/Fire alarm installer. We always had to ground our systems to the nearest cold water pipe. If it wasn't grounded properly,our system wouldn't work correctly.
IMO, no since 250.94 only requires the means of intersystem bonding termination be installed near the service equipment or grounding electrode conductor for the purpose of intersystem bonding, not that the systems actually be connected to it. Because each service provider has their own internal standards for grounding and bonding of their systems and equipment, which may differ substantially from the minimum requirements of the NEC, if the EC changes or alters it and doesn’t do it to the provider companies standard, he may be liable in the event of damage to the system or equipment and possibly even the building. I feel that the service providers should be notified by the property owner and/or the EC that the grounding and bonding for their systems may need to be updated after a service change is completed.
Re: Intersystem grounding block
#192993 03/14/1012:55 AM03/14/1012:55 AM
Kjay: We may be talking about two or more different scenarios here. For a new structure, no the EC is not responsible to do the bonding, only to install the 250.94 block.
On service changes reconnecting the LV bonding to the upgraded grounding and bonding system, for any existing data/comm/sat etc. This has been a 'standard' practice for the most part by the EC's. IMHO, the liability issue would be greater if the bonds were not re-connected after a service change.