TiVo Community Forum Archive 1

TiVo Community Forum Archive 1 (http://archive.tivocommunity.com/tivo-vb/index.php)
- HDTV TiVo Powered PVRs (http://archive.tivocommunity.com/tivo-vb/forumdisplay.php?forumid=36)
-- Coax Surge Protection (http://archive.tivocommunity.com/tivo-vb/showthread.php?threadid=181868)


Posted by ShiningBengal on 06-28-2004 06:49 PM:

quote:
Originally posted by aaronwt
It is grounded by the power meters. All the utilites are in the same location(within 3 feet) The meters are using the same grounding rod as the other utilites. I am connected to the same grounding rod.

Anyway it's been like this for 2.5 years and I don't have any problems, so I see no need to change it now.



How do you connect a ground "to the power meters?" And if you did this, how do you know they are at the same ground potential as the main service entrance? Are you saying the meter bank is connected to a ground rod, and you have somehow connected your ground to the meter bank? You can't get inside the meter enclosure--they are sealed by the utility. An you can't legally ground anything to the utility's equipment.

In this part of the country, a ground rod is almost NEVER used as a main system ground. They are notoriously unreliable as a system ground. Utilities use ground rods to ground their equipment because they do not usually have access to a water main to do this.

They only time they are permitted is if there is no other way to ground equipment. The water main is used 99.5% of the time, with the water meter jumpered to maintain the ground if the meter is removed for any reason.

These are the facts:

1. Ground loops are responsible for the vast majority of noise on CATV, cable, and other coaxial feeds to A/V equipment. The video noise is usually characterized by horizontal lines moving slowly up or down the screen.

2. Shielding on coaxial cable running a short distance past line voltage equipment will prevent the cable from picking up interference if it is grounded to a system ground.

3. If you have a ground loop, if the coax is grounded at any point to a system ground (i.e., through a 3-prong grounded plug at a wall outlet), it will eliminate the ground loop.

4. Surge protectors will not eliminate the effects of a ground loop. A good ground will.

I can understand your not wanting to spend time sorting this issue out for yourself, since you have eliminated the source of the interference. But for others, you should ALWAYS suspect a ground loop when you get video interference in your satellite system.

The best way to deal with a ground loop---assuming you have a grounded main service entrance---is to eliminate it with proper ground wiring.

When you hear hoof beats, don't look for zebras!

__________________
"Ignore 'em, m'dear. They're beneath your dignity." W.C. Fields


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