EETC Wiring & Installation Techniques 2 — Questions and Answers
Question 1: When installing EMT conduit, the maximum support spacing for conduit sized 3/4 inch and smaller is:
- 5 feet
- 8 feet
- 10 feet (Correct answer)
- 12 feet
Correct answer: 10 feet
NEC 358.30 requires EMT 3/4 inch and smaller to be supported within 3 feet of each box and at intervals not exceeding 10 feet.
Question 2: Which type of cable is specifically designed for direct burial without conduit?
- NM-B
- UF-B (Correct answer)
- AC cable
- MC cable
Correct answer: UF-B
UF-B (Underground Feeder) cable is rated for direct burial applications without requiring conduit.
Question 3: When pulling wire through conduit, the maximum fill percentage for three or more conductors is:
- 31% (Correct answer)
- 40%
- 53%
- 60%
Correct answer: 31%
NEC Chapter 9 Table 1 limits conduit fill to 31% of interior cross-sectional area when three or more conductors are installed.
Question 4: A 20-amp, 120-volt bathroom receptacle circuit must be:
- AFCI protected only
- GFCI protected only (Correct answer)
- Both AFCI and GFCI protected
- Protected by a standard breaker
Correct answer: GFCI protected only
NEC 210.8 requires all bathroom receptacles to have GFCI protection due to proximity to water sources.
Question 5: The minimum burial depth for PVC conduit (Schedule 40) under a residential driveway is:
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
NEC Table 300.5 requires PVC conduit under driveways to be buried at least 18 inches deep.
Question 6: When installing a service entrance, the weatherhead must be positioned so that:
- The service drop is below the weatherhead
- Conductors enter from the bottom facing down (Correct answer)
- The weatherhead faces horizontal
- The drip loops are above the weatherhead
Correct answer: Conductors enter from the bottom facing down
Conductors must enter the weatherhead from below with drip loops to prevent water from following the wires into the conduit.
Question 7: What is the purpose of using anti-oxidant compound when terminating aluminum conductors?
- To increase conductor flexibility
- To prevent corrosion and reduce resistance at connections (Correct answer)
- To color-code the termination
- To increase current-carrying capacity
Correct answer: To prevent corrosion and reduce resistance at connections
Anti-oxidant compound prevents aluminum oxidation at connections, which would increase resistance and create a fire hazard.
EETC Wiring & Installation Techniques 2
When installing EMT conduit, the maximum support spacing for conduit sized 3/4 inch and smaller is: