In a suspension insulator string, which of the following elements is typically included?

• A. A series of disc-shaped insulators connected by metal hardware and suspended from the cross-arm to carry the line voltage.
• B. A single solid ceramic rod with no external hardware.
• C. A metal frame housing a ceramic core without discs.
• D. A plastic tube enclosing the conductor.

Answer: (C)

Suspension insulator strings are built from several disc-shaped insulators arranged in series and connected by metal hardware, then suspended from the cross-arm to carry the line voltage. Each porcelain or glass disc adds insulation and, together, the stack provides a long creepage path that helps prevent leakage and flashover while accommodating slight movement of the conductor in wind. The metal fittings tie the discs together and attach the string to the cross-arm and to the conductor end fittings, giving both electrical isolation and mechanical support.

A single solid ceramic rod with no external hardware wouldn’t offer enough insulation distance or the necessary mechanical flexibility for suspending a line. A metal frame housing a ceramic core without discs describes a different type of insulator (not a suspension string), and a plastic tube enclosing the conductor would not provide the required insulation or structural function for suspending a line.