Journeyman Electrician Exam (NEC)Services, Feeders, and Branch CircuitsMedium
An industrial facility has a switchboard supplied by a 480V, 3-phase, 3-wire system. Per NEC 110.26(E), what is the minimum headroom required above this switchboard?
- A7.0 feet (2.13 meters)
- B6.5 feet (1.98 meters)
- C7.5 feet (2.29 meters)
- D6.0 feet (1.83 meters)
Show answer & explanationAnswer & explanation
Correct answer: B. 6.5 feet (1.98 meters)
According to NEC 110.26(E), the minimum headroom of working space about service equipment, switchboards, panelboards, or motor control centers must be 6.5 feet (1.98 meters). This requirement applies regardless of the voltage, up to 1000V, unless specific exceptions for dwelling units apply, which is not the case for an industrial facility.
Why the other options are wrong
- A. 7.0 feet is more than the minimum required, but not the specified minimum.
- C. 7.5 feet is more than the minimum required.
- D. 6.0 feet is less than the minimum required headroom.
Electrical Equipment Headroom
NEC 110.26(E) specifies the minimum vertical clearance (headroom) above electrical equipment, such as switchboards and panelboards, for safe access and work.
- Minimum 6.5 feet (1.98m) for equipment up to 1000V.
- Applies to service equipment, switchboards, panelboards, motor control centers.
- Ensures sufficient space for personnel and equipment manipulation.
Memory trick: Stand tall, work safely, keep your head clear.