What is the smallest equipment grounding conductor permitted to be installed with 1/0 AWG circuit conductors connected to a 150-amp breaker?

The smallest equipment grounding conductor that can be installed with 1/0 AWG circuit conductors connected to a 150-amp breaker is specified to ensure safety and compliance with the National Electrical Code (NEC). According to NEC guidelines, the grounding conductor must be appropriately sized to handle potential fault currents that could occur.

For 1/0 AWG conductors, the NEC provides a table (Table 250.122) that outlines the minimum size for equipment grounding conductors based on the rating of the circuit overcurrent protective device (in this case, the 150-amp breaker). According to this table, the minimum size for the equipment grounding conductor for a circuit protected by a 150-amp breaker is 6 AWG. This size ensures that the grounding system can effectively carry fault current without presenting a safety hazard.

On the other hand, options like 3 AWG, 1/0 AWG, and 2 AWG either exceed the necessary size or do not meet the minimum requirement as specified by the NEC. This underscores the importance of adhering to established codes for electrical installations to maintain safety and reliability in electrical systems.