Oklahoma Electrical Practice Exam

Exposed electrical nonmetallic tubing is permitted in buildings up to how many floors above grade?

1. 1 floor

2. 2 floors

3. 3 floors

4. 4 floors

The correct answer is: 3 floors

Exposed electrical nonmetallic tubing is permitted in buildings up to three floors above grade based on the National Electrical Code (NEC) and the Oklahoma amendments to it. This allowance is set to provide an optimal balance between safety and practicality in residential and commercial wiring installations. The rationale behind this allowance is that nonmetallic tubing, such as nonmetallic-sheathed cable (often referred to as NM cable), is more vulnerable to physical damage compared to other forms of conduit. As the height of a building increases, the risk of accidental damage to exposed wires is generally reduced due to the architectural features and design intended to protect electrical installations. By permitting exposed nonmetallic tubing in buildings up to three floors, the standard allows flexibility for installations that require visible wiring while maintaining a standard of safety and minimizing potential hazards. This permits electricians to efficiently manage wiring in taller buildings but not beyond a height where it could be more exposed to damage.