Which type of structure necessitates bonding for overhead service conductors when passing over it?

The requirement to bond overhead service conductors is particularly crucial for structures that are made of metal. This is because metal structures present specific risks in terms of electrical conductivity and the potential for electrical faults. Overhead conductors can carry significant current, and if a fault occurs, the metal structure can become energized, posing a serious shock hazard to anyone who comes into contact with it or is in the vicinity.

Bonding is a critical safety measure that ensures that any electrical fault on the overhead conductors is effectively grounded, minimizing the risk of electric shock and enhancing the safety of the entire electrical system. By bonding the service conductors to the metal structure, you create a pathway for fault current to flow back to ground, enabling protective devices (like circuit breakers or fuses) to operate correctly and isolate the fault.

In comparison, structures made from wood, plastic, or concrete do not require such bonding for overhead conductors because these materials do not have the same conductive properties as metal. In these cases, the risk of electrifying the structure is significantly lower, which is why bonding is specifically emphasized for metal structures in the context of overhead service conductors.