What type of equipment commonly uses liquidtight flexible nonmetallic conduit?

Liquidtight flexible nonmetallic conduit is designed for applications where moisture protection is needed along with flexibility. This conduit type can be utilized in a variety of environments where conditions may vary.

Outdoor lighting systems frequently require this type of conduit due to exposure to elements, ensuring that the wiring remains protected from rain and moisture. Indoor electrical outlets, particularly in areas where there might be occasional splashes or a higher risk of moisture, also benefit from this conduit, providing extra protection against potential damage. Furthermore, underground wiring, which is inherently vulnerable due to its placement and potential water exposure, is another prime application for liquidtight flexible nonmetallic conduit, ensuring safety and reliability in electrical installations.

Given that these applications cover a broad spectrum of uses, it is accurate that liquidtight flexible nonmetallic conduit is commonly used across outdoor lighting, indoor electrical outlets, and underground wiring. This versatility in application justifies the choice of 'All of the above' as the correct answer.