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ta240 4-Jun-2019 2:10 AM

grounding antenna
 
I have a grounding rod right next to the antenna but now need to connect that to the main house ground.

Our main house ground comes up from inside the wall into the breaker box and it is cement outside the wall in that area and our exterior is stucco.

Is the best option to bring the heavy gauge copper wire through the wall into the garage and then go down that wall, cut an opening from the inside the wall and clamp it onto that wire there?

Or should I go in through the attic and down the tube all the wiring comes up from the breaker box into the attic and hook it up there?

Any help is appreciated

GroundUrMast 4-Jun-2019 6:33 AM

Based on the information you've provided, I can't say that one route is better than the other. I would favor the shortest, most direct path.

Because you have a ground rod at the antenna location, you are correct to bond it to the existing electrical service grounding system... 6 AWG is the minimum diameter wire to be used in this case according to the National Electrical Code. If there was no grounding rod at the antenna location, a 10 AWG conductor would be acceptable per the NEC Article 810.

ta240 4-Jun-2019 11:25 PM

thanks for the quick reply.

OTAFAN 4-Aug-2019 11:14 PM

Quote:

Because you have a ground rod at the antenna location, you are correct to bond it to the existing electrical service grounding system... 6 AWG is the minimum diameter wire to be used in this case according to the National Electrical Code. If there was no grounding rod at the antenna location, a 10 AWG conductor would be acceptable per the NEC.
GroundUrMast:

Other than what the NEC calls for, why 6 AWG over 10 AWG, for instance?

6 AWG isn't that much larger in diameter than 10, and both are rated 600 volts. So, why wouldn't 8 or 10 AWG be just as effective?

Thanks again and all the best.....

GroundUrMast 5-Aug-2019 3:11 AM

FWIW the current carrying capacity of #6 AWG is about double that of #10 AWG. The voltage rating is for the insulation... Grounding and bonding conductors are not required to be insulated so you can use conductors with an insulation rating of any value.

My speculative answer is that the requirement is based in part on the extreme currents that will occur in the event of a lighting strike or heavy power fault to any part of the buildings electrical system which would force current through all all the available paths to ground...

Consider a situation where the power company's transformer suffers insulation breakdown or storm damage causes high voltage to come in contact with the service wires from the pole to the building -- In this case one would want all that energy to have a low resistance path to earth (ideally the electrical service grounding electrode system is supposed to provide that low resistance path). If your antenna system has a connection to earth by way of a rod of it's own, it will share part of the fault current. So the bonding jumper needs to be big enough to carry the current during such a fault. If you do not add a ground rod for the antenna system, a heavy fault current to the electrical service wouldn't have an intentional path to earth through the mast or coax bonding conductors, so they can be lighter gauge conductors than when an added ground rod is involved.

This argues against adding ground rods when installing an antenna system. By adding a ground rod separate of an existing electrical service grounding electrode system, you introduce what is called a ground loop. You then have to consider what will happen if there's a fault to the antenna system or the rest of the electrical system. Where the fault occurs will determine which direction current will travel in the bonding conductor between the antenna system and the rest of the electrical system. When a ground loop exists, fault currents that are less than the trip rating of a fuse or circuit breaker will persist and as a result, there will be voltage drop from one end of a bonding conductor to the other per ohms law. The voltage would likely be far below a danger threshold but may be enough to cause problems for electronic equipment. If you opt to add a ground rod, the heavier gauge bond will have less voltage drop if current does occur, that and the heavier gauge conductor will not fail at the lower current that would cause a light gauge conductor to fuse open.

OTAFAN 5-Aug-2019 3:51 AM

Quote:

FWIW the current carrying capacity of #6 AWG is about double that of #10 AWG.
I thought it might be something like this, GroundUrMast. Especially after rereading your various posts on subject. But I wasn't quite sure. Your expertise is once again much appreciated!


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