EETC Electrical Safety & Code Compliance 5 — Questions and Answers
Question 1: A technician is working inside an electrical panel with the main breaker off but the utility conductors still energized. What is the status of the line-side lugs?
- De-energized because the main breaker is open
- Still energized because utility conductors are not controlled by the main breaker (Correct answer)
- Safe to touch with Class 0 gloves only if testing
- De-energized only if the meter is pulled
Correct answer: Still energized because utility conductors are not controlled by the main breaker
Line-side lugs remain energized at utility voltage even with the main breaker off, because energy flows directly from the meter to those lugs.
Question 2: NEC 250.122 requires equipment grounding conductors to be sized based on:
- The load current
- The rating of the overcurrent device protecting the circuit (Correct answer)
- The wire gauge of the hot conductor
- The length of the circuit run
Correct answer: The rating of the overcurrent device protecting the circuit
NEC 250.122 sizes equipment grounding conductors (EGC) per Table 250.122, based on the overcurrent protective device rating.
Question 3: What is the purpose of a equipotential bonding grid in a swimming pool area?
- To provide a return path for pool pump current
- To eliminate voltage differences between metal parts that could shock bathers (Correct answer)
- To ground the pool lighting transformer
- To reduce chlorine electrolysis in the water
Correct answer: To eliminate voltage differences between metal parts that could shock bathers
Equipotential bonding connects all metal parts at the same electrical potential, preventing dangerous voltage gradients that could electrocute swimmers.
Question 4: According to NFPA 70E, which boundary is defined as the distance from an energized part within which a person could receive a second-degree burn from an arc flash?
- Limited approach boundary
- Restricted approach boundary
- Arc flash boundary (Correct answer)
- Prohibited approach boundary
Correct answer: Arc flash boundary
The arc flash boundary is the distance at which incident energy equals 1.2 cal/cm², the onset of second-degree burn threshold.
Question 5: A 20A, 120V circuit feeds a continuous load. Per NEC 210.20, the circuit's overcurrent device must be rated at least:
- 20A
- 25A (Correct answer)
- 30A
- 40A
Correct answer: 25A
NEC 210.20(A) requires the overcurrent device to be rated at 125% of the continuous load current (20A × 1.25 = 25A).
Question 6: Which NEC section requires tamper-resistant receptacles in all 125V, 15A and 20A receptacles in dwelling unit areas accessible to children?
- NEC 210.8
- NEC 210.52
- NEC 406.12 (Correct answer)
- NEC 410.36
Correct answer: NEC 406.12
NEC 406.12 requires tamper-resistant receptacles in dwelling units to protect children from inserting objects into energized slots.
Question 7: When performing an infrared (IR) thermography scan for hot spots in an electrical panel, panels must typically be:
- De-energized with covers removed
- Energized and under load with covers removed or panels open (Correct answer)
- Energized at no-load conditions
- Scanned from outside through the panel door only
Correct answer: Energized and under load with covers removed or panels open
IR thermography requires panels to be energized and under load to reveal thermal anomalies; loose connections only heat up under current flow.
EETC Electrical Safety & Code Compliance 5
A technician is working inside an electrical panel with the main breaker off but the utility conductors still energized.
What is the status of the line-side lugs?