What is the minimum size aluminum equipment grounding conductor for a 20-ampere twist-lock receptacle?

The correct answer is based on the National Electrical Code (NEC) which provides guidelines for grounding conductors. For a 20-ampere circuit, the NEC requires the use of a minimum equipment grounding conductor that is properly sized to ensure safety and effectiveness in fault conditions.

In particular, when it comes to aluminum conductors, the minimum size for a grounding conductor is determined by factors such as the size of the circuit conductors and the type of installation. For a 20-ampere receptacle, the NEC specifies that the minimum aluminum equipment grounding conductor should be 10 AWG.

This ensures that the grounding system is capable of handling potential fault currents without excessive heating or failure, thus providing adequate protection against electric shock and reducing the risk of equipment damage. The choice of 10 AWG is part of the standardized safety measures to maintain a reliable electrical installation.