A porcelain suspension insulator uses a ball-and-socket design which puts the insulating material under ? to create strength.

• A. Tension
• B. Compression
• C. Strain
• D. Shear

Answer: (B)

The key idea here is that porcelain insulators are strongest in compression, not in tension. The ball-and-socket design acts like a hinge that lets the insulator join rotate while converting the pulling load of the conductor into compressive stresses inside the insulator pieces. So when the line pulls downward, the forces push the insulator members together rather than trying to pull them apart. That compression strengthens the brittle porcelain and helps prevent cracks.

If the material were under tension, it would be more likely to crack because porcelain doesn’t handle pulling forces well. Strain is about deformation, not the specific type of loading, and shear isn’t the primary load path in this design. The essential point is that the ball-and-socket arrangement puts the insulating material under compression to achieve strength.