lasvegassatellite
Member
I work in the field of satellite installation and I am trying to develop a better understanding of grounding requirements.
It seems to me that requiring the mast of a television antenna to be grounded and that the coax wire be grounded as well was redundant. So, I tried to imagine scenarios where one might exist and the other didn't. I came up with the following:
If a television antenna was installed, but the wiring was 300 ohm twinlead wire (remember?) from the antenna to the television, then a ground block couldn't be installed on the wiring, right? I was thinking that the code requiring antenna masts be grounded is dated back to a time when you couldn't ground the wiring and so the only place to ground the system from overhead wiring, etc., was the mast of the antenna.
Now, enter CATV. When that system came along, the antenna and mast could be several miles away. Much too far for grounding if the ground block is miles away. So, I was thinking that the code was written to require CATV (and its coax wiring) be grounded at the subscriber's house.
So, with the two situations above, both systems could be present at the same house, both grounded in their respective fashions, and not be redundant.
Nowadays, television antennas and satellite dishes are installed using coax wiring. Since the NEC states that the coax is supposed to be grounded, and that ground method appears to be superior to the mast ground (#17 CCS), couldn't the code be altered to eliminate such redundancy? I am not suggesting that either requirement be eliminated entirely, but couldn't the television mast grounding requirement be rewritten to state that it is required ONLY when the signal wiring does not consist of coaxial wiring or if the wiring is not suitable for bonding to ground such as Cat 5e.
It would be nice if the NEC code did not require the redundancy we antenna installers face as a result of the code. I am aware of antennas that are in use that you can't ground the signal wire. Certain broadband antennas use Cat5e as the signal wire, and I think those would still have to be grounded at the mast, so that part of the code couldn't totally be eliminated.
The question is, could it be verified if the original intent of the code was for protection of systems that were separate at the time? I was contemplating researching this but I imagine it would require looking up text from the NEC as it had been written back when these antenna and CATV systems first started appearing. I could imagine the first antenna mast ground requirement is probably from an overhead line or drop coming into contact with a rooftop TV antenna, bringing dangerous current inside the house. I can also imagine CATV, which originally was distributed via overhead wiring, became hot from fallen power transmission lines, and brought dangerous current to a homeowner or cable installer. I am sure the code was written to prevent such situations, and redundancy was a side-effect of protecting both systems in a world where they existed separately. Any insight to this? Could redundancy possibly be eliminated in a future revision of code? I appreciate the input.
It seems to me that requiring the mast of a television antenna to be grounded and that the coax wire be grounded as well was redundant. So, I tried to imagine scenarios where one might exist and the other didn't. I came up with the following:
If a television antenna was installed, but the wiring was 300 ohm twinlead wire (remember?) from the antenna to the television, then a ground block couldn't be installed on the wiring, right? I was thinking that the code requiring antenna masts be grounded is dated back to a time when you couldn't ground the wiring and so the only place to ground the system from overhead wiring, etc., was the mast of the antenna.
Now, enter CATV. When that system came along, the antenna and mast could be several miles away. Much too far for grounding if the ground block is miles away. So, I was thinking that the code was written to require CATV (and its coax wiring) be grounded at the subscriber's house.
So, with the two situations above, both systems could be present at the same house, both grounded in their respective fashions, and not be redundant.
Nowadays, television antennas and satellite dishes are installed using coax wiring. Since the NEC states that the coax is supposed to be grounded, and that ground method appears to be superior to the mast ground (#17 CCS), couldn't the code be altered to eliminate such redundancy? I am not suggesting that either requirement be eliminated entirely, but couldn't the television mast grounding requirement be rewritten to state that it is required ONLY when the signal wiring does not consist of coaxial wiring or if the wiring is not suitable for bonding to ground such as Cat 5e.
It would be nice if the NEC code did not require the redundancy we antenna installers face as a result of the code. I am aware of antennas that are in use that you can't ground the signal wire. Certain broadband antennas use Cat5e as the signal wire, and I think those would still have to be grounded at the mast, so that part of the code couldn't totally be eliminated.
The question is, could it be verified if the original intent of the code was for protection of systems that were separate at the time? I was contemplating researching this but I imagine it would require looking up text from the NEC as it had been written back when these antenna and CATV systems first started appearing. I could imagine the first antenna mast ground requirement is probably from an overhead line or drop coming into contact with a rooftop TV antenna, bringing dangerous current inside the house. I can also imagine CATV, which originally was distributed via overhead wiring, became hot from fallen power transmission lines, and brought dangerous current to a homeowner or cable installer. I am sure the code was written to prevent such situations, and redundancy was a side-effect of protecting both systems in a world where they existed separately. Any insight to this? Could redundancy possibly be eliminated in a future revision of code? I appreciate the input.
