Sting wrote:is a ground rod enough
Sting, like you say it depends. It's important to under stand the ground wiring path to your TV. If for example your TV is using rabbit ears there is only one ground, the green safety ground in the AC power outlet. BUT, in the more typical case you have cable TV and/or and external antenna. Both of these have a grounding rod if install according to code. So far so good. BUT if the entry location of your antenna or cable TV coax is a different place than your service panel entrance wiring you could have a problem. Ideally all conductors entering your house enter at the same physical place and use the same earth grounding rod. What happens in a strong lightning strike current flows in the earth between any to different grounding rods. This very large current causes a voltage difference. If for example, this voltage difference is between your cable TV coax shield and your AC safety ground, this voltage also enters your electronics. It produces a current. How much depends. Too much and something burns out.
A more detailed explanation is here:http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
So what would I do? (1) Install a whole house protector in your circuit breaker panel. Buying your own is cheaper that renting or buying the meter socket type from the power company. (2) Use a quality surge suppressor on the TV power cord and (3) also have a surge suppressor on the TV coax/antenna input. Look for units that combine (2) & (3).
I've posted before on this topic. Do a search.