All the commercial satellite uplink sites and mountain top repeater sites I've worked at (lots of them) have massive grounding systems designed to survive a direct hit and they all use a minimum of 500 MCM cable for the ground ring and attachment to ground rods, cable entry ground points, etc.
These sites are usually designed by professional grounding companies who would be partially responsible if their design fails during a direct hit. I've replaced antennas blown apart by direct hits at some sites and there was no damage to the electronics so I trust the designs.
I've not worked on cell sites but would assume (hope) they are designed for direct hits. A cell site is also very small and everything is built with grounding in mind like power and antenna entry points. Grounding for an existing house to survive a direct hit is completely different and usually nothing is in the right place for adequate grounding.
The worst possible scenario would be for someone to use insufficient or wrong information to ground their antenna thinking it will withstand a lightning hit and it doesn't. There is a high price for a mistake like that.
I have lots of commercial experience grounding for lightning and have helped build many systems that do, but I would never design my own home lightning ground system because I don't have the ultimate knowledge or equipment to do that. Instead I ground to code and disconnect my antennas when storms are approaching.
prcguy
Grounding advice has turned into a "He says, I said" match between the different people that may stumble across a thread on the subject. Some people get really upset when another person doesn't agree with the first person.
There are even engineers that just can't stand anyone who even questions their word on how to do grounding. But one thing I will say is trying to use 500 MCM sized wire is not used but in a very few locations. The only place I have ever seen it used is in telephone central offices.
Grounding at the cellular sites around the country is done with #6 solid wire. Grounding of the commercial FM towers and the big microwave towers is done with #6 solid wires. Normally the solid wire is tinned so it won't corrode.
The NEC 810 (National Electrical Code) provides some real good guidance on grounding "Telecommunications Facilities" and antenna systems. Another place to obtain information is from your home owner's Insurance Company. Generally they have some guide line for owners to follow when installing TV antennas and ham antennas would also fall under the same classification.
I have spent many years in the cellular industry building the cellular sites. I have run into some real stupid contractors and local electrical inspectors. Many of the electrical inspectors have made fools out of them self's by demanding that grounding be done a particular way. I just ask them to show me in black and white where they are coming from to force you to do it their way. When this happens, your looking at an inspector that is trying to get a fast buck under the table before he will release your electrical meter to be installed. These same pain in the butt inspectors have also been fired on the spot by their bosses when they get that phone call from their office. It's amazing what a phone call to the inspection office to complain about what the inspector is doing will cause things to happen.
Bottom line here is if you ask 5 people how to do grounding, your going to get about 8 answers. It boils down to you have to figure out which way is the correct way. You do that by doing your homework and trying to find what your local jurisdiction is requiring. Don't forget the insurance company covering your house.
Grounding is not cheap, but neither is replacing your radio equipment and repairing damage to your house.
