Journeyman Electrician Exam (NEC)Wiring Methods and MaterialsMedium
A commercial electrician is installing a new 20-amp, 120-volt branch circuit in a suspended ceiling. The circuit is run using Type MC cable. What is the maximum distance between supports for the MC cable in a horizontal run?
- A4 1/2 feet
- B8 feet
- C3 feet
- D6 feet
Show answer & explanationAnswer & explanation
Correct answer: D. 6 feet
According to NEC 330.30(A), Type MC cable must be supported and secured at intervals not exceeding 6 feet (1.8 m). This ensures the cable maintains its position and prevents undue strain or sag.
Why the other options are wrong
- A. Incorrect. This distance is too short and not specified as the maximum support interval for MC cable.
- B. Incorrect. This distance is too long and does not meet the NEC requirement for MC cable support.
- C. Incorrect. This distance is too short and not specified as the maximum support interval for MC cable.
MC Cable General Support
The NEC requirement for the maximum spacing between supports for Type MC cable in general wiring applications.
- Prevents sagging and mechanical stress.
- Ensures cable integrity over its length.
- Specific distances are outlined in NEC Article 330.
Memory trick: MC Runs Six Feet Smoothly.