E2 Wiring Methods and Materials 3 — Questions and Answers
Question 1: Intermediate Metal Conduit (IMC) is permitted to be used as an equipment grounding conductor under which condition?
- Never — a separate EGC is always required
- Only with listed fittings installed per manufacturer instructions (Correct answer)
- Only indoors
- Only when bonded at both ends with locknuts
Correct answer: Only with listed fittings installed per manufacturer instructions
NEC 250.118(4) permits IMC to serve as an EGC when installed with listed fittings according to the manufacturer's instructions.
Question 2: What is the maximum trade size of Flexible Metal Conduit (FMC) that may be installed in lengths up to 6 feet without a separate equipment grounding conductor?
- 1/2 inch
- 3/4 inch (Correct answer)
- 1 inch
- 1-1/4 inch
Correct answer: 3/4 inch
Per NEC 250.118(5), FMC up to 3/4-inch trade size in lengths of 6 feet or less can serve as the EGC when listed fittings are used.
Question 3: In a commercial occupancy, Type AC cable (Armored Cable) must be secured within how many inches of every box or fitting?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
NEC 320.30(C) requires AC cable to be secured within 12 inches of every outlet box, junction box, or fitting.
Question 4: Which of the following conduit types is NOT permitted for use in cinder fill locations due to corrosion concerns?
- RMC with corrosion protection
- PVC Schedule 40
- EMT without corrosion protection (Correct answer)
- RTRC (fiberglass)
Correct answer: EMT without corrosion protection
NEC 358.10(B) prohibits EMT in cinder fill unless protected from the corrosive environment, as the thin wall is susceptible to attack.
Question 5: A run of rigid PVC conduit passes through a building expansion joint. The inspector should verify the presence of:
- A bonding jumper only
- An expansion coupling listed for the purpose (Correct answer)
- A flexible metallic coupling
- A union fitting with thread sealant
Correct answer: An expansion coupling listed for the purpose
NEC 352.44 requires an expansion fitting listed for PVC where the conduit crosses a structural expansion joint.
Question 6: What is the minimum bend radius for a 1-inch EMT conduit field bend to the inside of the bend?
- 2.5 inches
- 4 inches (Correct answer)
- 5 inches
- 8 inches
Correct answer: 4 inches
NEC Table 344.24 (referenced by 358.24) specifies a minimum 4-inch inside bend radius for 1-inch trade size conduit.
Question 7: Under the NEC, where must a conduit body (e.g., LB, LL, LR) be accessible?
- Only when containing splices
- Always, unless encased in concrete (Correct answer)
- It need not be accessible
- Only when installed outdoors
Correct answer: Always, unless encased in concrete
NEC 314.29 requires all junction and pull boxes, including conduit bodies, to remain accessible unless encased in concrete.
E2 Wiring Methods and Materials 3
Intermediate Metal Conduit (IMC) is permitted to be used as an equipment grounding conductor under which condition?