IEC NEC Code General Requirements 5 — Questions and Answers
Question 1: Under NEC 110.7, wiring integrity is required for completed wiring installations. What does this section specifically require?
- All wiring must be tested with a megohmmeter before energization
- Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in the Code (Correct answer)
- All conductors must have insulation resistance of at least 1 megohm per 1000V
- Wiring must be pressure-tested before energization
Correct answer: Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in the Code
NEC 110.7 requires that finished electrical wiring installations be free from short circuits, ground faults, and unintended ground connections.
Question 2: NEC 110.27 requires guarding of live parts. What methods are acceptable for guarding exposed live parts operating at 50 volts or more?
- Only by location in a secured electrical room
- By approved enclosures, elevation of 8 feet or more, location in a room accessible only to qualified persons, or suitable guarding by partitions or screens (Correct answer)
- By surrounding with warning tape at a 3-foot perimeter
- Only by installation inside locked metal enclosures
Correct answer: By approved enclosures, elevation of 8 feet or more, location in a room accessible only to qualified persons, or suitable guarding by partitions or screens
NEC 110.27(A) lists approved guarding methods: enclosures, elevation, restricted access rooms, or partitions/screens.
Question 3: What is the requirement under NEC 110.26(A)(2) regarding the width of dedicated electrical space above a panelboard?
- The width of the panelboard plus 12 inches on each side
- The width of the equipment extending from the floor or structural ceiling to a height of 6 feet above the equipment or to the structural ceiling, whichever is lower (Correct answer)
- No specific height requirement above the panel width
- The width of the panelboard to a height of 3 feet above the top
Correct answer: The width of the equipment extending from the floor or structural ceiling to a height of 6 feet above the equipment or to the structural ceiling, whichever is lower
NEC 110.26(E)(1) requires dedicated electrical space above equipment that extends the width of the equipment to a height of 6 feet or to the structural ceiling.
Question 4: According to NEC 110.5, what is the default conductor material when the Code references conductors without specifying the metal?
- Aluminum
- Copper (Correct answer)
- Copper-clad aluminum
- The least expensive available material
Correct answer: Copper
NEC 110.5 states that conductors shall be of copper unless otherwise specified, making copper the default conductor material in the Code.
Question 5: Under NEC 110.26(A)(1), what is the working space depth required for equipment rated 151-600 volts under Condition 1 (live parts on one side, no live or grounded parts on the other)?
- 3 feet
- 3.5 feet
- 4 feet (Correct answer)
- 5 feet
Correct answer: 4 feet
NEC 110.26(A)(1) Table requires 4 feet of working space depth for 151-600 volt equipment under Condition 1.
Question 6: NEC 110.10 addresses circuit impedance and other characteristics. What must the overcurrent protective device and all other equipment in a circuit have ratings or settings sufficient for?
- The maximum load current under normal conditions
- The short-circuit current available at the point of application (Correct answer)
- The full load current of the largest motor on the circuit
- The ambient temperature at the equipment location
Correct answer: The short-circuit current available at the point of application
NEC 110.10 requires that the overcurrent device, total impedance, component short-circuit current ratings, and other characteristics be selected to permit the available short-circuit current to be cleared without extensive damage.
Question 7: What does NEC 110.26(A)(1) Condition 3 combined with voltage over 600V (medium voltage) require for working space depth in installations over 600 volts?
- The same 4-foot depth as for 0-600 volt installations
- Depth increases significantly—NEC 110.34 governs with depths starting at 5 feet (Correct answer)
- Only qualified persons exempt from depth requirements at medium voltage
- Medium voltage equipment is exempt from working space requirements if in a vault
Correct answer: Depth increases significantly—NEC 110.34 governs with depths starting at 5 feet
For equipment over 600 volts, NEC 110.34 governs working space with greater depths (starting at 5 feet) to account for increased arc flash hazards.
IEC NEC Code General Requirements 5
Under NEC 110.7, wiring integrity is required for completed wiring installations.
What does this section specifically require?