EETC Wiring & Installation Techniques 3 — Questions and Answers
Question 1: When installing a ceiling fan, the electrical box must be rated for:
- At least 35 lb static load
- Fan support with the weight listed on the box (Correct answer)
- At least 50 lb with a safety factor of 2
- Standard light fixture load only
Correct answer: Fan support with the weight listed on the box
NEC 314.27(C) requires ceiling fan outlet boxes to be listed specifically for fan support, rated for the fan's weight.
Question 2: The color code for a 3-phase, 480-volt system's high-leg (wild leg) conductor is:
- Red
- Orange (Correct answer)
- Blue
- Brown
Correct answer: Orange
NEC 230.56 requires the high-leg (wild leg) of a 4-wire delta system to be identified with orange color.
Question 3: When using staples to secure NM cable, what is the maximum interval between staples in a vertical run?
- 2.5 feet
- 4.5 feet (Correct answer)
- 6 feet
- 8 feet
Correct answer: 4.5 feet
NEC 334.30 requires NM cable to be supported and secured at intervals not exceeding 4.5 feet (54 inches) along vertical runs.
Question 4: In a 3-wire, 240/120V single-phase system, if one hot leg fails, what happens to 120V loads on the remaining leg?
- They operate normally at 120V (Correct answer)
- They receive 240V and may be damaged
- They receive 0V and do not operate
- They receive 60V at half power
Correct answer: They operate normally at 120V
In a 3-wire system, each 120V load is connected between one hot leg and neutral, so loads on the intact leg continue to operate normally.
Question 5: What is the minimum cover required for a raceway installed under a concrete slab with no vehicular traffic?
- 0 inches — no cover needed (Correct answer)
- 2 inches
- 6 inches
- 12 inches
Correct answer: 0 inches — no cover needed
NEC Table 300.5 permits raceways installed under a concrete slab to have zero additional cover since the slab itself provides protection.
Question 6: When terminating conductors in a panelboard, which tool is used to verify proper torque on terminal screws?
- Digital multimeter
- Megohmmeter
- Calibrated torque screwdriver or wrench (Correct answer)
- Clamp-on ammeter
Correct answer: Calibrated torque screwdriver or wrench
Torque specifications on terminals must be met using a calibrated torque screwdriver or wrench to ensure proper electrical connections.
Question 7: Which wiring method is required when installing conductors in a hazardous (classified) location Class I, Division 1?
- NM cable
- EMT with set-screw fittings
- Rigid metal conduit (RMC) with threaded fittings (Correct answer)
- PVC conduit
Correct answer: Rigid metal conduit (RMC) with threaded fittings
Class I, Division 1 hazardous locations require threaded rigid metal conduit or threaded steel IMC to contain any ignition of flammable gases.
EETC Wiring & Installation Techniques 3
When installing a ceiling fan, the electrical box must be rated for: