EETC Wiring & Installation Techniques 5 — Questions and Answers
Question 1: When connecting a 3-phase motor, swapping any two of the three phase leads will:
- Increase motor speed by 15%
- Reverse the direction of motor rotation (Correct answer)
- Cause the motor to single-phase
- Have no effect on motor operation
Correct answer: Reverse the direction of motor rotation
Swapping any two phase conductors on a 3-phase motor reverses the rotating magnetic field, causing the motor shaft to spin in the opposite direction.
Question 2: What is the correct procedure when installing a new circuit breaker in a live panel?
- Work with both hands inside the panel simultaneously
- Wear insulated gloves and use insulated tools with the main breaker off if possible (Correct answer)
- Remove only the deadfront cover before starting
- Energize the breaker before connecting load wires
Correct answer: Wear insulated gloves and use insulated tools with the main breaker off if possible
Safe work practice requires insulated PPE and tools; turning off the main breaker eliminates shock risk from bus bars during breaker installation.
Question 3: A GFCI receptacle's 'Load' terminals protect:
- Only the GFCI receptacle itself
- Receptacles wired downstream on the same circuit (Correct answer)
- The circuit breaker protecting the circuit
- Receptacles on separate circuits in the same room
Correct answer: Receptacles wired downstream on the same circuit
Devices connected to the LOAD terminals of a GFCI receptacle receive GFCI protection, extending protection to downstream outlets.
Question 4: When installing conduit in a concrete pour, which type should be used?
- Electrical Metallic Tubing (EMT)
- PVC Schedule 40 or 80 (Correct answer)
- Flexible Metal Conduit (FMC)
- Armored Cable (AC)
Correct answer: PVC Schedule 40 or 80
PVC Schedule 40 or 80 conduit is used in concrete encasement because it resists corrosion from the alkaline concrete environment.
Question 5: The ampacity of a conductor must be derated when more than three current-carrying conductors are bundled together because:
- Voltage drop increases with more conductors
- Heat accumulates and cannot dissipate as effectively (Correct answer)
- The insulation thickness decreases
- The conductor resistance increases
Correct answer: Heat accumulates and cannot dissipate as effectively
Bundled conductors share heat that cannot dissipate as quickly, reducing each conductor's safe current-carrying capacity.
Question 6: What type of wire connector is listed for use with both aluminum and copper conductors in the same splice?
- Standard orange wire nut
- Purple wire nut (AL/CU listed) (Correct answer)
- Marrette connector
- Standard twist-on connector
Correct answer: Purple wire nut (AL/CU listed)
Wire connectors listed for AL/CU (aluminum/copper) use contain anti-oxidant compound and are rated for dissimilar metal connections to prevent galvanic corrosion.
Question 7: When installing outdoor receptacles exposed to weather, the cover must be rated:
- 'Weather Resistant' (WR) only when the receptacle is in use
- In-Use (extra duty) cover providing protection with or without a plug inserted (Correct answer)
- 'Weatherproof' cover that closes when the plug is removed
- Any standard indoor cover with a gasket added
Correct answer: In-Use (extra duty) cover providing protection with or without a plug inserted
NEC 406.9(B)(1) requires 'in-use' (extra duty) weatherproof covers for outdoor receptacles exposed to weather, protecting them even with cords plugged in.
EETC Wiring & Installation Techniques 5
When connecting a 3-phase motor, swapping any two of the three phase leads will: