Proper Ground or Bond? for CATV

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NovacaineFix

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Hello, forgive me if I have made any mistakes here as I am a new member and find the information here invaluable.
I am a CATV technician and have come into this problem with the proper use for a ground or bond.
Some background, our cable system has CATV, internet and phone service using voltages up to 90 volts.

Here is my dilemma:
In the past, we were told to use the ufer ground or cold water pipe [if it were copper] as the main source for "grounding" the CATV at the demark point using a F-81 ground block and 14 gauge copper wire.

Now we are told to "Bond" to power, meaning the main electrical panel, using a bonding plate that attaches to the outside of the meter panel and using the 14 gauge copper wire.

Which is correct or better for safety?

Here is the wrench in the system:

Now in some cases, the CATV demark comes up on the opposite side of the electrical panel and there may be a ground rod set at the demark location, is the safe or sufficient for safety? I am remembering that ground rods are for lightning and only to be used at the main panel. Am I wrong?

Another scenario is with MDU's [Multiple Dwelling Units or apartments or condo units]:
In these cases the CATV usually comes up into a closet or small utility room along with Telco, Gas and Electric. There is usually a ground rod that has Telco and others attached to it for "ground," and sometimes this is the ufer ground.

I am confused! I want to ground or bond correctly without violating any codes and I want to make sure that I and my fellow co-workers are doing this safely and correctly.

Could we use the Bonding plate to bond to the electrical panel equipment or should we use the ground rod?
Which should be used for safety?

I hate to keep asking so many questions, so I will leave with that. I appreciate any insight to which should be used to provide the best service with safety.

Thank you,
Bill
 
Do you have a code book? If so, take a look at 830.100. Here is a link to view it on line for free (you do have to register)

Just one point - if you need to add a grounding electrode, such as a ground rod, it must be bonded to the building electrode(s).
 
I think the code reference is actually 820.40 but does not matter which one because the method and reasons are the same.

I suspect you company made the change in policy to comply with NEC code requirements, and using a meter box clamp was the easiest and most convenient method they could come up with.

If you were using the ufer (concrete encased) or water pipe it more than likely was safe IF the AC electrical service was up to code and actually used the ufer and cold water pipe as the facility ground electrode. I can only guess and say your company ran into some issues where they installed CATV used the water pipe, and it was not used as an electrode causing problems like fire, damaged equipment, etc … So they made a policy change.

Rather than me answer each scenario you have let me explain why. If you bond your CATV to a ground electrode that is not part of the AC service ground electrode, in other words NOT intentionally bonded, and there were a fault or lightning event on one of the services, there would be a potential voltage difference between the two systems. This potential difference can cause fire, shock, and equipment damage. . Bond the two electrodes together to make them a common electrode, or use the same electrode and the problem of potential difference is minimized or eliminated.

So using one of your scenrios of the AC service is on one side of the house, and CATV on the opposite side. If you drive a rod for the CATV, you would have to bond the rod to the AC service ground electrod system to comply and make it safe. Again the problem is potential volatage difference in the event of a fault, especially lightning. Even without a fault there may be enough potential difference between the two to shock someone or make the service unusable like hum bars.
 
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I'll put it to you this way, I would rather bond to a ground electrode or the ufer ground IF it is part of the service ground instead of using that crummy meter pan clamp. Problem is you would really have to be an electrician to determine if a ground rod, cold water pipe or other object is a suitable ground. I think somebody in your company made the decision to use the clamp based on the fact that a meter pan should almost always provide the proper ground.

Is my memory correct in that the '08 NEC requires the EC to install a ground block outside the building by the service entrance for the telco and CATV grounds?

Some background, our cable system has CATV, internet and phone service using voltages up to 90 volts.

I'm interested in what the 90 volts is for.


-Hal
 
NovacaineFix said:
Hello, forgive me if I have made any mistakes here as I am a new member and find the information here invaluable.
Click to expand...
Welcome to the forum, Bill, and kudos for wanting to do it right! :smile:

Now in some cases, the CATV demark comes up on the opposite side of the electrical panel and there may be a round rod set at the demark location, is the safe or sufficient for safety?
Click to expand...
The problem with separate ground rods is that even an indirect lightning strike could set up a voltage gradient causing a difference of hundreds of volts between them, bringing in that voltage between the chassis of the cable box and the rest of the A/V or computer system.

Separate rods can actually create a greater hazard.

Another scenario is with MDU's:
In these cases the CATV usually comes up into a closet or small utility room along with Telco, Gas and Electric. There is usually a ground rod that has Telco and others attached to it for "ground," and sometimes this is the ufer ground.
Click to expand...
To me, that would be the best place to bond your grounding blocks. It addresses the real reasons that electrodes should be bonded.

I am confused! I want to ground or bond correctly without violating any codes and I want to make sure that I and my fellow co-workers are doing this safely and correctly.
Click to expand...
Again, that's a great attitude. We already see the cable-TV industry as one with too little concern for quality work.

Could we use the Bonding plate to bond to the electrical panel equipment or should we use the ground rod? Which should be used for safety?
Click to expand...
Either should be safe and compliant, as long as it's done properly. I still prefer the common-electrode method. Which has greater possibility of being done poorly without detection?
 
hbiss said:
I'm interested in what the 90 volts is for.
Click to expand...
They run 90VAC on the main trunk cables to power the amplifiers. They can run the AC and RF over the same coax. Normally the amplifiers strip off the AC but forward the RF into the feeder cables. Along the feeders there are taps which split the RF signal into a drop cable to each house.

In some systems they pass the 90VAC all the way to the house in order to power the Customer Premises Equipment, such as an ATA for your phone service. In the event of a power failure, the CATV-based phone would still work, just like with the Telco, because the power is coming from their end, not your home.
 
As for me I am one happy camper. I have Verizon FIOS. No more copper cable for me and the slow service and limitations. I fired Cox Cable and Verizon wireline. Get all my service through fiber now.
 
The 90 volts is for AC power insertion from a meter panel used to supply AC power for a line extender/amplifier. This is the power source we use to "power up" the CATV main plant.
The line extender serves as a balance point for maintaining proper signal levels to serve other customers further down the line. It is not uncommon for us to have 2 or 3 amps in line to complete a branch circuit of cable. In some of these the AC is used to supply power for the fiber transceiver on a fiber-node, basically the point where optical light from fiber converts to a RF signal.
 
As long as it works good and is what you want for the price you are paying, thats what I always say.

I have customers all the time asking which is better, and I always tel them the same thing [above]. In some areas, you have no choice or very few so for them the decision is harder to make.
 
I appreciate the replies from all, it is all great information.

I get frustrated when we are told one thing and then told to do it another way without a proper explaination of why??

I also talked to our resident electrician that we have, and he agrees with what everyone here has said. Great, I think he is going to bring this up with the senoir management to help eliminate any second guessing and hopefully clear up any and all confusion within the company.

If I may, the only thing that he said that was a little different, [unless it was how he explained it] was he was concerned that if we were using the meter bonding plate as the primary source for "grounding" that there may stil be a potential voltage issue. He also stated that whatever Electric is "grounded" to, use that, be it the ufer, ground rod or whatever.
Could I use both or is that a no no?
 
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