I just made the switch from cable to dish. When I asked the installer if he was going to run a separate ground wire to the sat dish he said that the grounding block that the coax connects to at the point of entry to the house is sufficient. Is this true?

Thanks!

If the grounding block is connected to an EFFECTIVE ground then it will protect you and your equipment from everything but a direct strike, and nothing will protect you from a direct strike.

Ken, you mean totally nothing at all? I was going to install my OTA antenna this weekend and I was just going to run my ground wire to the dish since its directly below it. So this just makes it worse...the antenna will be the highest point on the block.

Raymond,

Ken's correct in that most of the issues are resolved by grounding the cable shield. Static charges are bled off to reduce equipment damage and potentials that could attract the strike. No single point ground will completely protect you from a direct hit.

The actual requirements were discussed in the September post "Installed CM 4228..." You should ground the mast in accordance with NEC Section 810-21, as required by Section 810-15. Also, page 13 of the Dish Installation guide requires you to ground the dish and coax cable and directs you to the NEC.

It's your house, your equipment and you don't live next to me. Do as you wish. I ground them both.

ToddK

I forgot to explain my abreviations. The NEC is the National Electrical Code published by the National Fire Protection Association.
T.

Lightning is a powerful radio wave generator, and elevated wires are effective receiving antennas. A strike anywhere in your neighborhood will generate hundreds of volts (maybe thousands) on the surface of your coax. The main thing grounding does is protect your DTV receiver from these.

But the most common weak link is the ground itself. A good ground is a pipe sunk to a depth greater than the lowest level of the water table. But most hills are dry inside, making constructing a good ground a challenge there.

If you succeed, your dish becomes a lightning rod, which will increase the chances of a direct strike. Minimum expected dammage: destruction of coax and DTV receiver. Maximum: destruction of house. Most people can ignore this with reasonable safety. But if your dish is the highest point in the neighborhood you might want to think this through more carefully. You could lower the dish. But that would make your house more likely to take dammage in a direct strike, although you could rightfully claim it was not your fault. The most effective thing you can do is install a real lightning rod (with a separate ground). I advise most people not to bother adding a heavy ground wire to their coax. But if your dish is the highest thing in the neighborhood, it might just be a good idea.

http://www.dbsforums.com/reviews/tech1_5.html

thanks for the info Ken and Rfran. I think you have read my mind Ken. I've been thinking of just installing my antenna in the attic or slightly below the eaves. I've got 2 identical antennas from RS for $5 a piece (orig $50). So even with poor signals in the attic I might get away with using two! Any suggestions?

An attic mounting will reslut in the loss through absorbtion of about 10% of the signal at VHF frequencies, 60% at UHF, and 95% at DBS satellite frequencies.

Mounting 2 antennas in parallel is tricky. It will not work for DBS dishes (Each LNB has an oscillator, and they will not stay in phase.).

Ken thanks for the % loss at diff freqs. I didn't think it would be that high for UHF. Just to clarify, I was going to mount the OTA ant. in the attic not the sat dish.

Todd you might want to check the site that RFran pointed me to
http://www.dbsforums.com/reviews/tech1_5.html

Apparently if I followed your advise it would have made things worse or not or maybe...

Bottom line: Don't run a separate grounding wire!!!

Raymond (Arv2),

I'd seen that article by Mr. Colins a while ago. As I stated above, we do agree on the point aboout "grounding of the coaxial cable is done in the first place to provide a drain for the signals captured by the shield (which why we use coax in the first place) and to dissipate static electricity that would otherwise build up on the cable."

Interesting that the link to the actual text of the NEC in broken. No problem though, I have a hard copy. The NEC (if you check my earlier reference) says ground the mast. The Dish install section says ground the mast. The article says don't. It's the Internet; you're free to pick your own sources.

ToddK

Static electricity never builds up on coaxial cables. Coax is always grounded some place.