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FREQUENTLY ASKED QUESTIONS

  1. Q. Does providing electrical protection for your equipment, warrant the costs?

    A.  Always.  Properly placed and selected electrical protection equipment requires a one-time known expense, whereas lightning  can be reoccurring, is totally unpredictable, and often results in repair and replacement costs which are three times the one-time cost for the electrical protection of a typical cell site.  Such damage can play havoc with communication budgets in economically difficult times.
  1. Q. Does providing a capacitively coupled grounding system for the maximum dissipation of lightning strike energy into the earth, warrant the additional grounding effort and expense?

    A.  Yes.  Most damage to equipment and copper cable from a lightning strike is from the resulting Ground Potential Rise (GPR) rather than from a direct lightning surge.  Special grounding system design can reduce the possible GPR to a typical grounding system to less than 300 Volts 8 out of 10 times.  Reducing the lightning induced GPR to a grounding system from 6000 Volts-Peak to approximately 300 Volts-Peak can prevent damage to equipment at a typical cell site.

  1. Q.  Is providing a capacitively coupled grounding system design cost effective?

    A.  Yes.  A single lightning strike to a typical cell tower will average approximately $25,000 in equipment damages.  Sites experiencing lightning damage may be subjected to several strikes in a year, pushing repair costs to $50K or more.  However, the addition of a capacitively coupled grounding system design using radials, sacrificial anodes, and single-point grounding techniques will usually add only about $8000 to the total grounding expense.
  1. Q.  Does providing a recommended 5-ohm ground to remote earth with a typical grounding system using a single ground ring with ground rods, provide the same lightning energy dissipation as a 5-ohm ground to remote earth with a capacitively coupled grounding system?

    A.  Absolutely not.  Lightning surge current is made up of frequencies between DC and 2MHZ.  Thus, when both grounding systems are measured resistively at 5 ohms, the capacitively coupled grounding system for lightning provides a much lower surge impedance to remote earth, and thus is a much better grounding system.  It is difficult to determine exactly how much better, but I estimate that equipment protected by a 5-ohm ground to remote earth using a single ground ring with ground rods will experience a voltage rise five to ten times greater than equipment protected by a 5-ohm ground to remote earth with a capacitively coupled grounding system.
      

 


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