Grounding - Part 7, Improper Grounding
What can go wrong?
Presented by Todd Humphrey

Grounding a satellite dish is perhaps the most misunderstood aspect of a satellite system installation. Poor training, and a lack of understanding in grounding principles can result in grounding procedures that may cause more harm than good. The reason a satellite system is grounded is to provide a low resistance path to ground for any stray voltages that may build on the mast or coax. The main reason a house electrical system is grounded is the basically the same, to provide a path to ground for any unwanted voltages. Another reason for grounding is to maintain a neutral electrical potential between electrical devices, conductors, and metals that may become accidentally energized. Potential is the force that moves electrons to create voltage. Electrical potential is measured in volts. With zero potential there is zero voltage.

 

Testing Electrical Outlets

Electrical Outlet Tester

 

Before any satellite system is plugged into an electrical outlet, the electrical receptacle should be tested with a circuit tester.

On most testers, two yellow lights indicate proper wiring. When an outlet fails to pass, it should not be used to power a satellite system. An ungrounded outlet can lead to many problems.

 

When a satellite system is grounded properly, and the electrical outlet is not grounded, the satellite receiver and the coax that connects the receiver to the dish, provide the electrical ground for that outlet. If a surge suppressor is plugged into an ungrounded outlet, the suppressor will not operate properly. See Part 8, How grounds affect Surge Suppressors for more details.

 

Installing Ground Rods

 

The NEC requires all ground rods to be inter connected (bonded together) with at least a #6 copper wire. This requirement maintains a zero potential between ground rods. In some conditions two ground rods can create voltage between them.

Two ground rods with no bonding

Ground rods at different elevations or in soils of different PH values can create natural potential (voltage) between the ground rods.

This voltage can range from a nominal level to levels that create a noticeable shock. Depending on the polarity and strength of the potential, this voltage can cause operating problems in equipment, or lead to premature failures by increasing voltages to electrical components.

Bonding the two ground rods with a #6 copper wire eliminates differential potential.

 

Ground rods with #6 bonding wire

 

A satellite installation using a separate ground rod is not allowed unless bonded to the existing building ground with a #6.

 

Sharing Satellite Dishes

Sometimes a dish is shared by two homes when one home cannot receive a clear line-of-sight. If there is potential between the two homes grounding systems, problems can arise when the satellite systems are grounded. Some satellite receivers use grounded plugs. Even if the satellite coax and dish are not specifically grounded with a ground block, the system can be electrically grounded by only plugging in the satellite receiver. A grounded power plug does not meet the entire grounding needs for the satellite dish, but it does create potential grounding issues if the coax and dish ground are not properly installed.

 

Before connecting a receiver in one home, to an existing dish on another home, a voltage test should be performed between the coax from the new receiver and the existing satellite dish ground. If the voltage is more than 1 volt, the system may have problems. To be safe, the ground rods on both homes should be connected together with a #6 copper wire. You should contact your local electrical inspector before bonding the two ground rods together. Local codes may apply.

 

CAUTION - It is possible to have sufficient potential between two active ground systems to cause serious harm. NEVER come in physical contact with electrical conductors served by two power sources until you verify the absence of voltage between the conductors. Use insulated gloves or other means to keep yourself isolated during the test.

 

 

 

 

Return to Part 6 - Wildblue Grounding                    Go To Part 8 - How grounds affect Surge Suppressors

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