What is the minimum size metal device box recommended for an installation with isolated equipment grounding?

The minimum size metal device box recommended for installations with isolated equipment grounding is based on the need to accommodate various wiring methods and ensure safe grounding practices. The selected answer indicates that a 3" × 2" × 31/2" device box is necessary to provide adequate space for the grounding conductors and any additional wiring associated with the equipment.

This box size is important because the larger dimension allows for proper separation of the grounding (or grounding electrode) conductors from the other conductors within the box. This separation is crucial in preventing electrical interference and maintaining the integrity of the grounding system, which is essential for the safety and functionality of electrical systems.

The specified size also facilitates easier installation, ensuring that there is enough room for all connections and terminations without excessive strain on the wires, which can lead to potential failure points. Overall, this size allows for compliance with codes and standards regarding grounding and equipment safety, ensuring both the reliability and safety of the electrical installation.

Other size options do not provide the necessary volume or space needed to accommodate the conductors in a way that meets safety and performance standards, which makes them unsuitable for installations requiring isolated equipment grounding.