National Electrical Code (NEC) 9th Edition – 2025/2026 Study
Guide
This guide is designed to test key concepts from the National Electrical Code with an
emphasis on foundational rules, calculations, and safety principles. The answers are
illustrated in the specified format.
Disclaimer: This guide is based on the NEC and its enduring principles. For the most
current code, always refer to the latest officially adopted edition (NFPA 70) and consult
with your local Authority Having Jurisdiction (AHJ).
Chapter 1: General & Definitions
1. What is the primary purpose of the National Electrical Code?
ANSWER ✓ The primary purpose of the NEC is the practical safeguarding of persons
and property from hazards arising from the use of electricity.
2. What does the NEC consider a "Qualified Person"?
ANSWER ✓ A qualified person is one who has skills and knowledge related to the
construction and operation of the electrical equipment and installations and has
received safety training to recognize and avoid the hazards involved.
3. Are the NEC requirements intended to be applied retroactively to existing
installations?
ANSWER ✓ No, the NEC is generally not retroactive unless an existing installation is
specifically modified, repaired, or renovated, at which point the new rules apply to the
work performed.
4. What is the definition of an "Accessible (as applied to wiring methods)"?
ANSWER ✓ Accessible means capable of being reached without removing building
finishes, structures, or permanent barriers, and is not permanently closed in by such
elements.
, 5. What is the definition of an "Readily Accessible"?
ANSWER ✓ Readily accessible means capable of being reached quickly for operation,
renewal, or inspections without requiring those to whom ready access is requisite to
climb over or remove obstacles or use portable ladders, etc.
Chapter 2: Wiring & Protection (Article 100, 200, 210, 215, 220)
6. What is the minimum general lighting load calculation for a dwelling unit, in
volt-amperes per square foot?
ANSWER ✓ The minimum general lighting load for dwelling units is 3 volt-amperes
per square foot, calculated from the outside dimensions.
7. How many 125-volt, 15- or 20-ampere receptacle outlets are required in a
dwelling unit kitchen countertop?
ANSWER ✓ A receptacle outlet must be installed at every kitchen countertop space 12
inches or wider. Countertops separated by range tops, sinks, or appliances are
considered separate spaces. All countertop receptacles must be within 24 inches of the
countertop's edge.
8. What is the minimum branch-circuit rating for a single receptacle on an
individual branch circuit?
ANSWER ✓ The branch-circuit rating must not be less than the rating of the single
receptacle. A single 50-ampere receptacle requires a minimum 50-ampere branch
circuit.
9. What is the required minimum size for equipment grounding conductors (EGCs)
of branch circuits?
ANSWER ✓ The minimum size is based on the rating of the overcurrent device. For a
20-ampere circuit, the minimum copper EGC is 12 AWG. For a 60-ampere circuit, it is 10
AWG. (Refer to NEC Table 250.122).
10. How many 20-ampere small-appliance branch circuits are required for the
kitchen and dining areas of a dwelling?
, ANSWER ✓ At least two 20-ampere small-appliance branch circuits are required to
supply receptacle outlets in the kitchen, pantry, breakfast room, dining room, and similar
areas.
11. What is the NEC requirement for "AFCI" protection in dwelling unit bedrooms?
ANSWER ✓ Arc-Fault Circuit Interrupter (AFCI) protection is required for all 120-volt,
single-phase, 15- and 20-ampere branch circuits supplying outlets in dwelling unit
bedrooms, living rooms, dining rooms, and other specific living areas.
12. What is the NEC requirement for "GFCI" protection for bathrooms?
ANSWER ✓ Ground-Fault Circuit Interrupter (GFCI) protection is required for all 125-
volt, 15- and 20-ampere receptacles installed in bathrooms.
13. What is the required working space depth in front of a 480V panelboard with
exposed live parts on one side and grounded metal on the other?
ANSWER ✓ For Condition 2 (exposed on one side, grounded on the other), the
minimum required working space depth is 3.5 feet for systems 301V-1kV. (Refer to NEC
Table 110.26(A)(1)).
14. How is the feeder or service load calculated for a residential electric clothes
dryer?
ANSWER ✓ The load for a household electric clothes dryer is 5000 watts (or the
nameplate rating, whichever is larger) per dryer. For four or more dryers, a demand
factor can be applied.
15. What is the minimum headroom for working spaces about service equipment,
switchboards, or panelboards?
ANSWER ✓ The minimum headroom is 6.5 feet. The width must be at least 30 inches or
the width of the equipment, whichever is greater.
16. Where is a "Main Disconnecting Means" required for a service?
ANSWER ✓ Each service must have a main disconnecting means, and it must be
located at a readily accessible location either outside or inside the building, nearest
the point of entrance of the service conductors.
17. What is the maximum number of disconnects allowed for a single service?
Guide
This guide is designed to test key concepts from the National Electrical Code with an
emphasis on foundational rules, calculations, and safety principles. The answers are
illustrated in the specified format.
Disclaimer: This guide is based on the NEC and its enduring principles. For the most
current code, always refer to the latest officially adopted edition (NFPA 70) and consult
with your local Authority Having Jurisdiction (AHJ).
Chapter 1: General & Definitions
1. What is the primary purpose of the National Electrical Code?
ANSWER ✓ The primary purpose of the NEC is the practical safeguarding of persons
and property from hazards arising from the use of electricity.
2. What does the NEC consider a "Qualified Person"?
ANSWER ✓ A qualified person is one who has skills and knowledge related to the
construction and operation of the electrical equipment and installations and has
received safety training to recognize and avoid the hazards involved.
3. Are the NEC requirements intended to be applied retroactively to existing
installations?
ANSWER ✓ No, the NEC is generally not retroactive unless an existing installation is
specifically modified, repaired, or renovated, at which point the new rules apply to the
work performed.
4. What is the definition of an "Accessible (as applied to wiring methods)"?
ANSWER ✓ Accessible means capable of being reached without removing building
finishes, structures, or permanent barriers, and is not permanently closed in by such
elements.
, 5. What is the definition of an "Readily Accessible"?
ANSWER ✓ Readily accessible means capable of being reached quickly for operation,
renewal, or inspections without requiring those to whom ready access is requisite to
climb over or remove obstacles or use portable ladders, etc.
Chapter 2: Wiring & Protection (Article 100, 200, 210, 215, 220)
6. What is the minimum general lighting load calculation for a dwelling unit, in
volt-amperes per square foot?
ANSWER ✓ The minimum general lighting load for dwelling units is 3 volt-amperes
per square foot, calculated from the outside dimensions.
7. How many 125-volt, 15- or 20-ampere receptacle outlets are required in a
dwelling unit kitchen countertop?
ANSWER ✓ A receptacle outlet must be installed at every kitchen countertop space 12
inches or wider. Countertops separated by range tops, sinks, or appliances are
considered separate spaces. All countertop receptacles must be within 24 inches of the
countertop's edge.
8. What is the minimum branch-circuit rating for a single receptacle on an
individual branch circuit?
ANSWER ✓ The branch-circuit rating must not be less than the rating of the single
receptacle. A single 50-ampere receptacle requires a minimum 50-ampere branch
circuit.
9. What is the required minimum size for equipment grounding conductors (EGCs)
of branch circuits?
ANSWER ✓ The minimum size is based on the rating of the overcurrent device. For a
20-ampere circuit, the minimum copper EGC is 12 AWG. For a 60-ampere circuit, it is 10
AWG. (Refer to NEC Table 250.122).
10. How many 20-ampere small-appliance branch circuits are required for the
kitchen and dining areas of a dwelling?
, ANSWER ✓ At least two 20-ampere small-appliance branch circuits are required to
supply receptacle outlets in the kitchen, pantry, breakfast room, dining room, and similar
areas.
11. What is the NEC requirement for "AFCI" protection in dwelling unit bedrooms?
ANSWER ✓ Arc-Fault Circuit Interrupter (AFCI) protection is required for all 120-volt,
single-phase, 15- and 20-ampere branch circuits supplying outlets in dwelling unit
bedrooms, living rooms, dining rooms, and other specific living areas.
12. What is the NEC requirement for "GFCI" protection for bathrooms?
ANSWER ✓ Ground-Fault Circuit Interrupter (GFCI) protection is required for all 125-
volt, 15- and 20-ampere receptacles installed in bathrooms.
13. What is the required working space depth in front of a 480V panelboard with
exposed live parts on one side and grounded metal on the other?
ANSWER ✓ For Condition 2 (exposed on one side, grounded on the other), the
minimum required working space depth is 3.5 feet for systems 301V-1kV. (Refer to NEC
Table 110.26(A)(1)).
14. How is the feeder or service load calculated for a residential electric clothes
dryer?
ANSWER ✓ The load for a household electric clothes dryer is 5000 watts (or the
nameplate rating, whichever is larger) per dryer. For four or more dryers, a demand
factor can be applied.
15. What is the minimum headroom for working spaces about service equipment,
switchboards, or panelboards?
ANSWER ✓ The minimum headroom is 6.5 feet. The width must be at least 30 inches or
the width of the equipment, whichever is greater.
16. Where is a "Main Disconnecting Means" required for a service?
ANSWER ✓ Each service must have a main disconnecting means, and it must be
located at a readily accessible location either outside or inside the building, nearest
the point of entrance of the service conductors.
17. What is the maximum number of disconnects allowed for a single service?
