Grounding and Bonding Flashcards

What is the minimum size equipment grounding conductor required for a 200-ampere circuit per NEC Table 250.122?

Answer: 4 AWG copper

NEC Table 250.122 requires a 4 AWG copper equipment grounding conductor for circuits rated up to 200 amperes.

Which NEC article specifically addresses grounding and bonding requirements?

Answer: Article 250

NEC Article 250 covers all general requirements for grounding and bonding of electrical installations.

What is the purpose of bonding jumpers in a commercial electrical system?

Answer: Ensure electrical continuity and reduce impedance

Bonding jumpers ensure electrical continuity and create a low-impedance path to facilitate overcurrent device operation during a fault.

A separately derived system must have its grounding electrode conductor connected at which point?

Answer: Source of the separately derived system

Per NEC 250.30(A), the grounding electrode conductor for a separately derived system must connect at the source (e.g., transformer secondary).

What is the maximum resistance allowed between a grounding electrode and the earth per NEC 250.53(A)(2)?

Answer: 25 ohms

NEC 250.53(A)(2) requires supplemental electrodes when a single rod, pipe, or plate electrode has resistance exceeding 25 ohms.

In a commercial building with multiple services, bonding between services is required to prevent what condition?

Answer: Voltage differences that can cause hazardous current flow

Bonding between multiple services prevents dangerous voltage potential differences that could cause hazardous current flow between systems.

Which conductor connects the grounded service conductor to the grounding electrode at the service?

Answer: Grounding electrode conductor

The grounding electrode conductor (GEC) connects the grounded service conductor (neutral) to the grounding electrode system.