Pin insulators are typically used for what span length?

• A. Very long spans
• B. Underground sections
• C. Short spans
• D. Submerged spans

Answer: (C)

Pin insulators are used where overhead lines span only a short distance between poles. They’re mounted directly on a wooden pole pin and carry the conductor with a simple, inexpensive setup. This works well for short spans because the mechanical load from the conductor (weight, wind, and sag) can be carried by a single insulator and pin without needing more complex suspension hardware. For longer spans, the forces become too great for a single pin and insulator, so suspension or other insulator types are used instead. Underground or submerged sections don’t use pin insulators because there isn’t an exposed overhead conductor to insulate. So, pin insulators are typically used for short spans.