PVC electrical conduit.

Primary Uses
Electrical Conduit: The most common use for gray PVC is as a protective pathway for power and communication cables, both above ground and underground. Unlike white plumbing PVC, gray conduit is formulated with UV stabilizers, making it suitable for outdoor use without becoming brittle from sunlight exposure.
High-Pressure Plumbing: Gray Schedule 80 PVC has thicker walls than the more common Schedule 40 white PVC, allowing it to handle higher water pressure in commercial and industrial applications.
Drainage and Waste: In some regions, gray pipes are used for sewage, waste, and vent systems within buildings due to their resistance to corrosion and chemicals