Grounding Cable

Old 04-09-04, 08:22 PM
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Grounding Cable

The cable guy came out to my house today. According to him there's too much amperage on my digital cable T.V. line. He said there shouldnt be any amperage on it. He also said it's most likely coming from the shared ground outside the house. Now i dont really know what he meant by that or what the problem is? Can anyone explain?

Old 04-10-04, 06:02 AM
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A common ground for all the electric potential in a house is something that NEC requires. If there is a potential between the cable tv feed and ground, it stands to reason that the voltage must exist on the cable itself.

If the voltage is present and should not be, then it is leaking into the cable line from somewhere. Electricity has to have a path over which to flow. For this situation, I would check the cable line from its source to see if there is a contact between any source of electricity and the cable. You could check your outlet where the cable box, television, or other piece of equipment in your entertainment center with a common feed to the other devices draws its power to ensure that there is not an open ground or reversed polarity for a two prong connection.

If there is voltage present that should not be, how much there is can help track this down. I don't know how much voltage is supposed to be on a cable line, probably not much. That should help. If there is 110 volts, then there must be a leak from an AC line.

If the voltage on the line is the proper amount and the amperage is too high, then somewhere something is consuming all this power.

Consider a 110 volt outlet in your house. 110 volts of electricity is supplied. If it is a 15 amp circuit, it will allow 15 amps of current to be drawn before the 15 amp breaker opens the circuit. If your appliance draws only 3 amps, that will be all that is supplied. You don't push amperage down a line the way the voltage is pushed. That is, the 110 volt line always provides 110 volts. That is why a 27 volt device won't last long before it burns up on the circuit. The current in amperes is what the device draws at the voltage supplied.

I would be interested in more information from the cable guy. The voltage must be right, since he did not complain about it. If the amperage draw is too high, then it must be goin somewhere and the protection device on the cable line is not limiting it to the desired amount.
Old 04-26-04, 07:56 AM
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Hypothesis---- The Grounding Electrode ( Ground Rod) for the Cable connection is adjacent to the System Grounding Electrode which Grounds the Neutral Service Conductor. The resistance of the System Grounding Electrode is 25 Ohms. 25 Ohms is considered a "low" value.

If a "leakage" current of 3 amps thru the Sytem Grounding Electrode exists, the is a potential of 3 X 25 = 75 volts across the System Grounding Electrode. This potential may be imposed on the Cable-connection because of the adjacent Grounding Electrodes.

To quote from the "NEC Handbook"-----"The solution is to Bond the two Grounding Electrodes together. When one system (power) is raised above Ground Potential,the second system (communication)is raised to the same potential"

If you have two Ground-rods as explained, you will have to connect a Bonding-Jumper between the Rods, which connects the exposed ends of the Rods together. This will "short-circuit" any voltage that may be present across the Grounding Electrode resistance. Use #6 copper wire for the Bonding Jumper.

For more detailed information, refer to the "NEC Handbook", 2002, pages 205-207

Good Luck & Enjoy the Experience!!!!!!!!!!!!1

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