Oklahoma Electrical Practice Exam

What is the smallest working space headroom height required for service equipment and switchboards?

1. 72 inches

2. 75 inches

3. 78 inches

4. 80 inches

The correct answer is: 78 inches

The smallest working space headroom height required for service equipment and switchboards is 78 inches. This requirement ensures that there is enough clearance above service equipment to allow for safe access and maintenance. Adequate headroom is critical to prevent accidents and injuries when personnel are working around or on equipment. The National Electrical Code (NEC) specifies this minimum height to mitigate the risk of contact with live parts while providing ample working room to facilitate proper operation and adjustments. The height also accounts for various factors, including the average height of workers and the need for additional space when tools or equipment are used in the vicinity of the service equipment. Having a minimum of 78 inches allows for sufficient room for technicians to work comfortably while also reducing the likelihood of interference with any overhead structures or equipment.