What signs indicate a cracked porcelain insulator?

• A. Visible cracks, chips, or discoloration and any leakage or arcing marks.
• B. Smooth, uncracked surface with uniform color.
• C. Only minor scratches on the metal hardware.
• D. No signs of damage but weathering.

Answer: (A)

When a porcelain insulator is cracked, the dielectric barrier is compromised, so moisture and contaminants can create a conductive path and even cause surface discharges. The telltale signs to look for are visible cracks or chips in the porcelain, discoloration from heat or contamination, and leakage or arcing marks on the surface. These indicate the insulation is no longer reliable and requires action. In contrast, a smooth, uncracked surface with uniform color suggests good condition; minor scratches on metal hardware don’t reflect the porcelain’s integrity, and weathering alone without visible damage isn’t a definite sign of a crack.