CSLB C-10 Electrical ContractorWiring Methods and MaterialsEasy
An electrician installs a straight run of EMT conduit along an exposed wall in a commercial building. According to the NEC, EMT must be securely fastened within 3 feet of each outlet box and at what maximum interval along the remaining run?
- AEvery 8 feet
- BEvery 6 feet
- CEvery 10 feet
- DEvery 12 feet
Show answer & explanationAnswer & explanation
Correct answer: C. Every 10 feet
NEC 358.30 requires EMT to be securely fastened within 3 feet of every outlet box, junction box, cabinet, or termination, and at intervals not exceeding 10 feet along the remaining length of the run.
Why the other options are wrong
- A. 8 feet is not a standard EMT support spacing.
- B. 6 feet is not the EMT support interval specified in NEC 358.30.
- D. 12 feet exceeds the maximum allowed support spacing.
EMT Support Spacing
Electrical metallic tubing (EMT) must be securely fastened at regular intervals to prevent sagging and mechanical damage.
- Support required within 3 ft of each box or termination.
- Maximum support interval along the run is 10 ft.
- Applies to NEC Article 358 (EMT).
Memory trick: 'Three near the box, ten in a row' keeps EMT secure.