Fiberglass ladders provide electrical insulation only when they are clean and dry and are effective up to what voltage?

• A. Clean and dry fiberglass ladders insulate for voltages under 600V
• B. Fiberglass ladders never insulate
• C. Wet and dirty fiberglass ladders insulate for voltages under 600V
• D. They only insulate up to 120V

Answer: (A)

Fiberglass ladders can insulate only if their surface is clean and dry. Dirt or moisture on the surface creates conductive paths that reduce or defeat the ladder’s insulating ability. When clean and dry, a fiberglass ladder is considered to insulate up to about 600 volts, so it provides protective insulation for voltages under that level. If the ladder is wet or dirty, that insulation is no longer reliable, even at lower voltages. The other statements miss this reality: wet or dirty conditions compromise insulation; a ladder is not guaranteed to insulate only up to 120V; and fiberglass ladders do provide insulation when clean and dry.