What is the maximum diameter for suspension porcelain insulator disks?

• A. 8 1/2"
• B. 11 1/2"
• C. 10"
• D. 12"

Answer: (B)

The size of a suspension porcelain insulator is set by standardized disk diameters used in the hardware and voltage classes. The larger the disk, the more mechanical strength the stack has, but it also makes the insulator longer, heavier, and harder to fit with the suspension clamp and required electrical clearance. Among common, widely used sizes, 11 1/2 inches is the largest standard diameter that fits typical suspension hardware and pole spacing. Smaller sizes like 8 1/2" and 10" exist for lighter or shorter strings, while 12" isn’t a standard size for these insulators. So the maximum diameter you’d encounter for suspension porcelain insulator disks is 11 1/2 inches.