Select the size of the aluminum equipment grounding conductor required for a circuit protected by a 70-ampere fuse.

To determine the appropriate size of the aluminum equipment grounding conductor for a circuit protected by a 70-ampere fuse, it's necessary to refer to the National Electrical Code (NEC) guidelines. The NEC outlines specific requirements for grounding conductors based on the size of the overcurrent protection device.

For an aluminum grounding conductor, the NEC specifies that the size should be based on the rating of the overcurrent protective device. In general, for aluminum conductors, the required size of the equipment grounding conductor is typically one size larger than the copper equivalent because aluminum has a lower conductivity than copper.

According to the NEC, for a circuit with a 70-ampere overcurrent protection device, the recommended size for an aluminum grounding conductor is 6 AWG. This is because the grounding conductor must be able to safely carry fault currents without overheating or causing damage. The minimum size is established to ensure safety and compliance with electrical code requirements.

Thus, selecting a 6 AWG aluminum grounding conductor ensures proper grounding, which is critical for the safety and effective operation of electrical systems. It provides adequate protection while meeting regulatory standards.