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Georgia Low Voltage Practice study materials
Georgia Low Voltage Practice study resources

Georgia Low Voltage Practice: Grounding, Bonding, and Surge Protection

Georgia Low Voltage Practice · Work through your exam, one topic at a time.

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Grounding, Bonding, and Surge Protection

What this domain tests

Grounding, Bonding, and Surge Protection tests whether you can distinguish grounding from bonding and apply single-point grounding to low-voltage systems. Expect grounding electrode conductors, equipment bonding, communications bonding, ground loops, and surge protective device placement.

Core rules

  • Grounding connects a system to earth. Bonding connects metal parts together to create an equal-potential path. Bonding is not optional; it is what clears faults and limits voltage differences.
  • The grounding electrode conductor is sized from NEC Table 250.66 based on the service conductor. It is not sized from the load current.
  • Communications systems have their own bonding rules. For example, NEC 800.100 requires a bonding conductor for the primary protector that is not smaller than 14 AWG copper or 12 AWG aluminum.
  • A ground loop occurs when multiple ground paths create a voltage difference. Low-voltage signal systems often need a single-point reference, but safety and code-required bonding must not be removed to fix noise.
  • Surge protective devices should be installed in a cascaded arrangement: service entrance, panel, and sensitive equipment. Lead length matters; long, looping leads reduce performance.
  • Separately derived systems and isolated grounds are often misunderstood. An isolated ground is not a substitute for equipment grounding.

Worked example

A 200 A service uses 2/0 copper service-entrance conductors. Table 250.66 requires a 4 AWG copper grounding electrode conductor. If the installer uses 6 AWG because it fits the lug, the installation fails the table even though 6 AWG might carry the normal neutral current. The reasoning is that the grounding electrode conductor is sized for fault and lightning energy, not for the load. For a communications protector, the separate 800.100 minimum applies; do not assume the 4 AWG service rule automatically sets every low-voltage bond.

Traps

  • Calling an earth rod a bonding jumper.
  • Removing safety grounds to eliminate hum.
  • Using a ground rod as the only equipment-grounding path.
  • Installing a surge device with long, coiled leads.
  • Confusing isolated ground receptacles with ungrounded equipment.