Master Electrician Practice Exam

What is the minimum size copper common grounding electrode conductor required to run through a building to four separately derived systems?

1. 2/0 AWG

2. 3/0 AWG

3. 4/0 AWG

4. 1 AWG

The correct answer is: 3/0 AWG

The minimum size copper grounding electrode conductor required to connect to four separately derived systems is determined by the National Electrical Code (NEC) regulations, specifically addressing grounding and bonding. For separately derived systems, the code specifies that the grounding electrode conductor must have sufficient size to ensure safety and system effectiveness. In this case, 3/0 AWG copper is the appropriate size because it provides adequate capacity to handle fault currents and ensure a reliable path to ground. This helps mitigate potential electrical hazards and ensures that all systems maintain proper grounding integrity. The size also accommodates the combined ground fault protection that may be present across multiple systems, thus ensuring that all derived systems are effectively bonded together. When considering other sizes for grounding conductors, such as 2/0 AWG, 4/0 AWG, or 1 AWG, they either exceed the necessary capacity or do not meet the required standards for multiple separately derived systems as specified in the code. Therefore, 3/0 AWG copper stands as the minimum acceptable size for this scenario, ensuring compliance while maintaining safety and functionality.