Master Electrician Practice Exam

In a commercial building with a 600 ampere service, what is the minimum size aluminum grounding electrode conductor permitted for the metal water piping system?

1. 2 AWG

2. 4 AWG

3. 2/0 AWG

4. 4/0 AWG

The correct answer is: 4/0 AWG

The minimum size aluminum grounding electrode conductor for a metal water piping system in a commercial building with a 600 ampere service is 4/0 AWG. This determination is based on the National Electrical Code (NEC), which specifies that for services 600 amperes or greater, the size of the grounding electrode conductor must be no less than 4/0 AWG aluminum. Aluminum has different conductivity characteristics compared to copper, hence the larger size is required to safely carry any fault current that may occur. The grounding electrode conductor is critical for ensuring that a metallic water piping system is bonded to the electrical system, providing a low-resistance path for fault currents which helps to protect both personnel and equipment. The chosen size ensures compliance with safety standards while minimizing the risk of overheating and electrical hazards. Other sizes such as 2 AWG, 4 AWG, and 2/0 AWG do not meet the NEC requirements for a 600 amp service, which is why those options are not correct. Essentially, 4/0 AWG ensures the conductor adequately satisfies the safety and performance requirements mandated for such electrical systems.