I have the AT9 and WB68 switch grounded. I have a channel master in the attic for OTA already grounded via an inline grounding block for the one OTA line I currently have running to one receiver (which was close to the outside grounding blocks). Now I want to split the OTA signal to run to more than the one TV - possibly two more TVs.
I will have to drop the cables from the attic antenna and splitter into a couple of the upstairs rooms between the walls (similar to how a couple of my Directv runs are as well that run in the attic). How important is it to ground the attic antenna at all, and if one line is grounded is that okay if the other cables are not grounded? If each line or the antenna itself should be grounded, what are recommendations in doing this.
A ground of the length that would be required on an attic antenna would provide no lightning protection whatsoever. The long ground lead (from the antenna to wherever it runs to eventually get to "ground") would have so much inductance that it would be seen by the induced strike as a large resistor. There is no effective protection for typical consumers from direct strikes, so let's not even talk about that. To properly protect against direct hits costs many hundreds of dollars, perhaps thousands. Safety grounds (preventing electrical shock) is quite easy.
It is pretty unlikely that your attic antenna would represent the shortest (read as lowest impedance) path to ground, so lightning is not that big of a problem, and there isn't really anything you can do that will help the situation anyway.
What you should be concerned about are two things:
1. Surge protection: make sure every piece of equipment surge protected.
2. Protect your most delicate and expensive equipment with a UPS.
The HR20 should be plugged into a ups if you are in a lightning prone area. Your TV, if powered by a lamp (like DLPs) should be plugged into a ups to keep the bulb fan going for a short period of time AFTER a power failure.
If you go right to the UPS solution, you get both protection for power winkies during thunderboomers and surge protection at the same time. It is a very wise investment. Forget the attic antenna ground...it's a mirage, invest in a UPS for the HR20 and TV and you end up with the best and least expensive protection for both.
Lightning protection is a very involved science, some say art. If you have an outside antenna, well elevated, there are things to do that can help quite a bit. In an attic, there is no practical solution. (and the risk is very low) If you want to learn more about "real" lightning protection, go to the Polyphaser web site (google it), and you will see what is really involved.