What term describes the outermost layer of insulated conductors in a raceway system?

The term that describes the outermost layer of insulated conductors in a raceway system is the insulating jacket. This layer serves several critical functions, including providing electrical insulation to prevent unintended contact with other conductors or environmental elements, protecting the conductors from physical damage, and serving as a barrier against moisture and chemicals.

The insulating jacket also contributes to the overall durability and safety of the wiring system, ensuring compliance with electrical codes and standards. The jacket is designed to be resilient and is usually made of materials that can withstand various conditions, like temperature changes and exposure to ultraviolet light, thereby enhancing the longevity of the conductors inside the raceway.

In contrast, the other options represent different concepts in electrical wiring. The grounding shield is an additional layer primarily focused on safety and primarily used to protect against electrical noise or interference. The electrical envelope is not a standard term used in raceway systems. The phase conductor refers to the actual conductive wires that carry electrical current, thus does not describe the outer protective layer of those conductors.