Q1: What is the primary purpose of the National Electrical Code (NEC)?
ANSWER The practical safeguarding of persons and property from hazards
arising from the use of electricity.
Q2: What NEC article covers general installation requirements? ANSWER
Article 110 - Requirements for Electrical Installations.
Q3: What is the minimum headroom for working spaces about service
equipment? ANSWER 6½ feet (2.0 m) or the height of the equipment,
whichever is greater.
Q4: What is the minimum width of working space in front of electrical
equipment? ANSWER 30 inches (750 mm) or the width of the equipment,
whichever is greater.
Q5: How often is the NEC updated? ANSWER Every three years.
Q6: What does NFPA stand for? ANSWER National Fire Protection
Association.
Q7: What voltage is considered the threshold between low voltage and high
voltage in most contexts? ANSWER 1000 volts for AC systems.
Q8: What is the definition of a "qualified person" per the NEC? ANSWER
One who has skills and knowledge related to the construction and operation of
electrical equipment and installations and has received safety training to
recognize and avoid the hazards involved.
Q9: What is the minimum depth of clear working space for equipment
operating at 277V to ground (Condition 1)? ANSWER 3 feet (900 mm).
Q10: What color must the grounded conductor (neutral) be? ANSWER
White or gray, or three continuous white or gray stripes on other than green
insulation.
,Q11: What is the maximum voltage permitted for dwelling unit branch
circuits supplying luminaires? ANSWER 120 volts between conductors.
Q12: What is the minimum size copper grounding electrode conductor for
a 200-amp service? ANSWER 4 AWG copper or 2 AWG aluminum.
Q13: Where must GFCI protection be provided in dwelling units?
ANSWER Bathrooms, garages, outdoors, crawl spaces, unfinished basements,
kitchens (countertop receptacles), sinks, boathouses, bathtubs/shower stalls.
Q14: What is the maximum spacing for receptacle outlets in dwelling unit
habitable rooms? ANSWER 12 feet measured horizontally along the wall line,
with no point along the wall more than 6 feet from a receptacle.
Q15: What is the minimum burial depth for rigid metal conduit under a
building? ANSWER 0 inches (contact with building is permitted).
Q16: What ampacity must a single receptacle on an individual branch
circuit have? ANSWER Not less than the rating of the branch circuit.
Q17: What is the maximum number of disconnects permitted for a service?
ANSWER Six switches or six circuit breakers.
Q18: At what height must receptacles be installed in accessible locations?
ANSWER Not less than 15 inches (380 mm) above the floor.
Q19: What is the minimum size branch circuit required for a bathroom in
a dwelling? ANSWER 20 amperes.
Q20: What article covers branch circuit and feeder calculations?
ANSWER Article 220.
Q21: What is the general lighting load for dwelling units? ANSWER 3 VA
per square foot.
Q22: What is the demand factor for four appliances on the same feeder in a
dwelling? ANSWER 75%.
Q23: What is the minimum service size for a one-family dwelling?
ANSWER 100 amperes, 3-wire.
Q24: How many small-appliance branch circuits are required in a dwelling
kitchen? ANSWER At least two 20-ampere circuits.
Q25: What is the minimum rating for a laundry branch circuit? ANSWER
20 amperes.
, Q26: What is the maximum length of a flexible cord used for permanent
connection? ANSWER Generally limited to 6 feet, though specific
applications vary.
Q27: Where must arc-fault circuit interrupter (AFCI) protection be
provided? ANSWER All 120-volt, 15- and 20-ampere branch circuits
supplying outlets in dwelling unit kitchens, family rooms, dining rooms, living
rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets,
hallways, laundry areas, and similar rooms or areas.
Q28: What is the minimum cover requirement for underground rigid
nonmetallic conduit not under a building? ANSWER 18 inches.
Q29: What is the minimum ampacity required for the grounded conductor
(neutral) of a feeder? ANSWER Sufficient to carry the maximum unbalanced
load.
Q30: What is the maximum voltage drop recommended for branch circuits
and feeders combined? ANSWER 5%.
Q31: What article covers outlet, device, pull and junction boxes?
ANSWER Article 314.
Q32: What is the minimum volume required in a box for each size 14 AWG
conductor? ANSWER 2.00 cubic inches.
Q33: What is the minimum volume required in a box for each size 12 AWG
conductor? ANSWER 2.25 cubic inches.
Q34: What is the minimum volume required in a box for each size 10 AWG
conductor? ANSWER 2.50 cubic inches.
Q35: What is the maximum number of quarter bends (90° bends)
permitted in a conduit run? ANSWER Four quarter bends (360° total).
Q36: What is the minimum trade size for rigid metal conduit? ANSWER ½
inch.
Q37: What percentage of conduit fill is permitted for one conductor?
ANSWER 53%.
Q38: What percentage of conduit fill is permitted for two conductors?
ANSWER 31%.
Q39: What percentage of conduit fill is permitted for three or more
conductors? ANSWER 40%.
ANSWER The practical safeguarding of persons and property from hazards
arising from the use of electricity.
Q2: What NEC article covers general installation requirements? ANSWER
Article 110 - Requirements for Electrical Installations.
Q3: What is the minimum headroom for working spaces about service
equipment? ANSWER 6½ feet (2.0 m) or the height of the equipment,
whichever is greater.
Q4: What is the minimum width of working space in front of electrical
equipment? ANSWER 30 inches (750 mm) or the width of the equipment,
whichever is greater.
Q5: How often is the NEC updated? ANSWER Every three years.
Q6: What does NFPA stand for? ANSWER National Fire Protection
Association.
Q7: What voltage is considered the threshold between low voltage and high
voltage in most contexts? ANSWER 1000 volts for AC systems.
Q8: What is the definition of a "qualified person" per the NEC? ANSWER
One who has skills and knowledge related to the construction and operation of
electrical equipment and installations and has received safety training to
recognize and avoid the hazards involved.
Q9: What is the minimum depth of clear working space for equipment
operating at 277V to ground (Condition 1)? ANSWER 3 feet (900 mm).
Q10: What color must the grounded conductor (neutral) be? ANSWER
White or gray, or three continuous white or gray stripes on other than green
insulation.
,Q11: What is the maximum voltage permitted for dwelling unit branch
circuits supplying luminaires? ANSWER 120 volts between conductors.
Q12: What is the minimum size copper grounding electrode conductor for
a 200-amp service? ANSWER 4 AWG copper or 2 AWG aluminum.
Q13: Where must GFCI protection be provided in dwelling units?
ANSWER Bathrooms, garages, outdoors, crawl spaces, unfinished basements,
kitchens (countertop receptacles), sinks, boathouses, bathtubs/shower stalls.
Q14: What is the maximum spacing for receptacle outlets in dwelling unit
habitable rooms? ANSWER 12 feet measured horizontally along the wall line,
with no point along the wall more than 6 feet from a receptacle.
Q15: What is the minimum burial depth for rigid metal conduit under a
building? ANSWER 0 inches (contact with building is permitted).
Q16: What ampacity must a single receptacle on an individual branch
circuit have? ANSWER Not less than the rating of the branch circuit.
Q17: What is the maximum number of disconnects permitted for a service?
ANSWER Six switches or six circuit breakers.
Q18: At what height must receptacles be installed in accessible locations?
ANSWER Not less than 15 inches (380 mm) above the floor.
Q19: What is the minimum size branch circuit required for a bathroom in
a dwelling? ANSWER 20 amperes.
Q20: What article covers branch circuit and feeder calculations?
ANSWER Article 220.
Q21: What is the general lighting load for dwelling units? ANSWER 3 VA
per square foot.
Q22: What is the demand factor for four appliances on the same feeder in a
dwelling? ANSWER 75%.
Q23: What is the minimum service size for a one-family dwelling?
ANSWER 100 amperes, 3-wire.
Q24: How many small-appliance branch circuits are required in a dwelling
kitchen? ANSWER At least two 20-ampere circuits.
Q25: What is the minimum rating for a laundry branch circuit? ANSWER
20 amperes.
, Q26: What is the maximum length of a flexible cord used for permanent
connection? ANSWER Generally limited to 6 feet, though specific
applications vary.
Q27: Where must arc-fault circuit interrupter (AFCI) protection be
provided? ANSWER All 120-volt, 15- and 20-ampere branch circuits
supplying outlets in dwelling unit kitchens, family rooms, dining rooms, living
rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets,
hallways, laundry areas, and similar rooms or areas.
Q28: What is the minimum cover requirement for underground rigid
nonmetallic conduit not under a building? ANSWER 18 inches.
Q29: What is the minimum ampacity required for the grounded conductor
(neutral) of a feeder? ANSWER Sufficient to carry the maximum unbalanced
load.
Q30: What is the maximum voltage drop recommended for branch circuits
and feeders combined? ANSWER 5%.
Q31: What article covers outlet, device, pull and junction boxes?
ANSWER Article 314.
Q32: What is the minimum volume required in a box for each size 14 AWG
conductor? ANSWER 2.00 cubic inches.
Q33: What is the minimum volume required in a box for each size 12 AWG
conductor? ANSWER 2.25 cubic inches.
Q34: What is the minimum volume required in a box for each size 10 AWG
conductor? ANSWER 2.50 cubic inches.
Q35: What is the maximum number of quarter bends (90° bends)
permitted in a conduit run? ANSWER Four quarter bends (360° total).
Q36: What is the minimum trade size for rigid metal conduit? ANSWER ½
inch.
Q37: What percentage of conduit fill is permitted for one conductor?
ANSWER 53%.
Q38: What percentage of conduit fill is permitted for two conductors?
ANSWER 31%.
Q39: What percentage of conduit fill is permitted for three or more
conductors? ANSWER 40%.
