Licensed Electrical Contractor NEC General Requirements 3 — Questions and Answers
Question 1: Per NEC 110.26(A)(1), what is the minimum clear working space depth in front of equipment operating at 151–600V to ground with exposed live parts on one side and a grounded surface on the other (Condition 2)?
- 3 feet
- 3.5 feet (Correct answer)
- 4 feet
- 4.5 feet
Correct answer: 3.5 feet
NEC Table 110.26(A)(1) specifies 3.5 feet (42 inches) of working clearance for 151–600V Condition 2.
Question 2: What does NEC 110.22 require to be legibly marked on disconnecting means?
- The installer's name and license number
- The load served and the source of supply (Correct answer)
- The ampere rating and voltage rating only
- The date of installation and inspection
Correct answer: The load served and the source of supply
NEC 110.22 requires each disconnecting means to be legibly marked to indicate the load served and its source of supply.
Question 3: According to NEC 110.12, electrical equipment must be installed in a:
- Listed enclosure only
- Neat and workmanlike manner (Correct answer)
- Location accessible only to qualified persons
- Dry location unless weatherproof rated
Correct answer: Neat and workmanlike manner
NEC 110.12 requires all electrical equipment to be installed in a neat and workmanlike manner.
Question 4: Under NEC 110.14(C)(1), the temperature rating of a conductor connected to a 60°C-rated terminal on a device rated 100A or less must be based on:
- 75°C ampacity tables
- 90°C ampacity tables
- 60°C ampacity tables (Correct answer)
- The highest rated insulation available
Correct answer: 60°C ampacity tables
NEC 110.14(C)(1) requires that conductors connected to 60°C-rated terminals on equipment 100A or less be sized using the 60°C ampacity column.
Question 5: What is the NEC definition of a 'qualified person'?
- A licensed electrician with 5+ years of experience
- One who has skills and knowledge related to the construction and operation of electrical equipment and installations (Correct answer)
- Any person with an electrical contractor license
- A journeyman electrician approved by the AHJ
Correct answer: One who has skills and knowledge related to the construction and operation of electrical equipment and installations
The NEC Article 100 definition of a qualified person is one who has skills and knowledge related to the construction and operation of electrical equipment and has received safety training.
Question 6: NEC 110.10 requires that the components of a circuit be selected so that the circuit's impedance characteristics allow the overcurrent device to:
- Trip within 3 cycles under any condition
- Clear fault current without extensive damage to components (Correct answer)
- Limit fault current to 10,000A maximum
- Coordinate with downstream devices at all times
Correct answer: Clear fault current without extensive damage to components
NEC 110.10 requires circuit components to be selected to permit the overcurrent device to clear a fault without extensive damage to electrical components.
Question 7: Per NEC 110.26(D), when is dedicated electrical space required above panelboards and switchboards?
- Only in commercial occupancies
- For all equipment rated over 1200A
- For the width and depth of the equipment from the floor to a height of 6 feet above or to the structural ceiling, whichever is lower (Correct answer)
- Only when equipment is located outdoors
Correct answer: For the width and depth of the equipment from the floor to a height of 6 feet above or to the structural ceiling, whichever is lower
NEC 110.26(D) requires dedicated electrical space from the floor to 6 feet above the equipment or to the structural ceiling for panelboards and switchboards.
Licensed Electrical Contractor NEC General Requirements 3
Per NEC 110.26(A)(1), what is the minimum clear working space depth in front of equipment operating at 151–600V to ground with exposed live parts on one side and a grounded surface on the other (Condition 2)?