ICC Residential Electrical Inspectors Practice Exam

What is an acceptable method for ensuring continuity when bonding metallic service raceways to metal service equipment?

1. Welding

2. Listed bonding type lock nuts

3. Connecting with screws

4. Using conduit connectors

The correct answer is: Listed bonding type lock nuts

The most appropriate method for ensuring continuity when bonding metallic service raceways to metal service equipment is the use of listed bonding type lock nuts. These lock nuts are specifically designed to maintain a reliable electrical connection between the raceway and the service equipment while ensuring proper bonding. Listed bonding type lock nuts are tested and approved for that specific purpose, and they help achieve the necessary conductivity and mechanical stability needed for effective bonding. This is crucial for safety because it reduces the risk of electric shock and fire hazards by ensuring that any fault current can be safely directed to ground. Other methods, while they may provide some degree of connection, do not meet the same standards for reliability and safety. For instance, welding can create a permanent bond, but it may not be practical for all applications, and skilled labor is required. Connecting with screws may not provide sufficient contact area or continuity over time, especially if there is any loosening due to vibration or thermal expansion. Using conduit connectors is also a common practice, but they may not specifically meet the bonding requirements without additional bonding means. Thus, the use of listed bonding type lock nuts provides the safest and most effective solution for ensuring continuity in bonding metallic service raceways to metal service equipment.