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NEC CODE NEC 2020

Service Entrance, Branch Circuits & Feeder Conductors 2 — NEC 2020 Edition

Free NEC 2020 practice test on service entrance, feeders, and branch circuits. Covers feeder ampacity sizing, dwelling and commercial lighting load demand, receptacle load calculations, service disconnect rules, and unbalanced load. Simple English, full explanations.

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The National Electrical Code (NFPA 70) is the benchmark standard for safe electrical installation in the US. It is updated every 3 years by the NFPA.

Study the edition adopted by your state. As of 2025, most states use the 2020 or 2023 NEC. These tests are written to the 2023 edition.

The most tested articles are 100 (Definitions), 200–250 (Wiring & Grounding), 300–314 (Wiring Methods), 400–411 (Conductors), 430 (Motors), and 700–701 (Emergency Systems).

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This Service Entrance, Branch Circuits & Feeder Conductors 2 — NEC 2020 Edition has 30 questions with detailed answers and NEC references. Take the full test, review every wrong answer, and look up the NEC article it references before moving on.

Tip: Use the NEC index (back of the book) — find answers by keyword, not by article number.

Topics covered: NEC articles 100, 210, 220, 240, 250, 300, 310, 430, and special occupancies.
Passing score: Aim for 80%+ on NEC code tests before exam day.
Questions: 30 multiple-choice, one correct answer each

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Service Entrance, Branch Circuits & Feeder Conductors 2 — NEC 2020 Edition — Question List

Question 1: A feeder supplies 60 A of continuous load and 30 A of noncontinuous load. What is the minimum standard overcurrent device rating?

90 A
100 A
110 A
125 A

NEC Reference: NEC 215.3

Question 2: A dwelling unit has a general lighting connected load of 4,000 VA. What is the total demand load after applying the lighting demand factor?

3,350 VA
4,000 VA
3,200 VA
3,600 VA

NEC Reference: NEC Table 220.42

Question 3: What is the branch-circuit load calculated for a show window that is 10 feet wide?

2,000 VA
1,800 VA
1,600 VA
2,200 VA

NEC Reference: NEC 220.14(G)

Question 4: How many 15-ampere, 14 AWG branch circuits are minimally required to supply the general lighting load for a 2,000 sq ft dwelling unit at 120 volts?

NEC Reference: NEC 220.14(J) / 210.11(A)

Question 5: A retail shop has 20 duplex receptacles, each on its own yoke. What is the calculated load for these receptacles?

300 volt-amperes
3,600 volt-amperes
1,800 volt-amperes
36,000 volt-amperes

NEC Reference: NEC 220.14(I)

Question 6: In a shopping complex, what is the maximum number of receptacles generally permitted on a 20-ampere, 120-volt breaker, using the standard 180 VA per receptacle?

NEC Reference: NEC 220.14(I)

Question 7: A single piece of equipment has five receptacles built into it. What is the total calculated load for these receptacles?

450 volt-amperes
900 volt-amperes
600 volt-amperes
800 volt-amperes

NEC Reference: NEC 220.14(I)

Question 8: A 1,200 sq ft dwelling unit is supplied at 120/240 V. What is the minimum number of 15-ampere, 2-wire general lighting branch circuits?

NEC Reference: NEC 220.14(J) / 210.11(A)

Question 9: What is the minimum laundry circuit load that must be considered for each 2-wire laundry branch circuit in a dwelling unit?

1,500 Volt-Amperes
1,200 Volt-Amperes
1,000 Volt-Amperes
800 Volt-Amperes

NEC Reference: NEC 220.52(B)

Question 10: For sizing a feeder or service neutral, how is the maximum unbalanced load defined?

The largest single appliance load
The difference between the largest and smallest loads
The total load of all phases added together
The maximum net calculated load between the neutral and any one ungrounded conductor

NEC Reference: NEC 220.61(A)

Question 11: What is the maximum number of service disconnecting means permitted for one service, grouped at one location?

6
2
10
There is no limit

NEC Reference: NEC 230.71(B)

Question 12: For a one-family dwelling, what is the minimum rating required for the service disconnecting means?

100 amperes
60 amperes
125 amperes
200 amperes

NEC Reference: NEC 230.79(C)

Question 13: What is the general minimum vertical clearance of overhead service conductors above a roof surface?

3 ft
8 ft
8 ft 6 in.
10 ft

NEC Reference: NEC 230.24(A)

Question 14: A service mast supports the service-drop conductors. What must it be?

Of adequate strength, or supported by braces or guys
Any listed raceway, regardless of strength
Made only of PVC conduit
Shorter than 3 ft above the roof

NEC Reference: NEC 230.28

Question 15: What is the general minimum size of underground service-lateral conductors?

4 AWG copper or 2 AWG aluminum
8 AWG copper or 6 AWG aluminum
6 AWG copper or 4 AWG aluminum
1/0 AWG copper or 2/0 AWG aluminum

NEC Reference: NEC 230.31(B)

Question 16: Per the NEC informational note, what is the recommended maximum COMBINED voltage drop for a feeder plus branch circuit together?

NEC Reference: NEC 215.2(A) Informational Note

Question 17: Service-entrance cable is subject to physical damage. Which method may protect it?

Schedule 80 PVC conduit
Flexible metal conduit
Schedule 40 PVC conduit
A wrap of vinyl tape

NEC Reference: NEC 230.50(A)

Question 18: How must each service disconnecting means be marked?

With the electrician's license number
With the date of installation
With the utility meter number
Permanently marked to identify it as a service disconnect

NEC Reference: NEC 230.70(B)

Question 19: Where must the service disconnecting means be installed?

Anywhere in the building
At a readily accessible location nearest the point of entrance of the service conductors
In a locked closet with the key kept by the utility
In an attic above the service entrance

NEC Reference: NEC 230.70(A)(1)

Question 20: For a grounded service, where may the grounding electrode conductor connect to the grounded service conductor?

Only at the first branch-circuit panelboard
At any accessible point from the service drop or lateral to the service disconnect neutral terminal
Only at the utility transformer
At any subpanel on the premises

NEC Reference: NEC 250.24(A)(1)

Question 21: Under the 10-foot feeder tap rule, tap conductors not over 10 feet long must have an ampacity of not less than what?

The load served or terminating device rating
Any size at all
Half the feeder size
A fixed 15 amperes

NEC Reference: NEC 240.21(B)(1)

Question 22: In a multiple-occupancy building, what access must each occupant have to service disconnecting means?

Access to the disconnect(s) serving that occupancy, unless the building has continuous management supervision
No access; only the utility may operate them
Access to every disconnect in the building
Access only through the building owner by appointment

NEC Reference: NEC 230.72(C)

Question 23: Ungrounded service-entrance conductors must have an ampacity not less than what?

Half the rating of the service disconnect
The utility transformer rating
The rating of the service disconnecting means
Twice the rating of the service disconnect

NEC Reference: NEC 230.42(B)

Question 24: Where must a service head be located?

Inside the attic
At least 10 ft from the point of attachment
Below the point of attachment, for drainage
Above the point of attachment of the service-drop conductors

NEC Reference: NEC 230.54(C)

Question 25: For service equipment rated 0-150 volts to ground under Condition 1, what is the minimum required clear working space depth?

3 feet
1 foot
6 feet
10 feet

NEC Reference: NEC Table 110.26(A)(1)

Question 26: For a single dwelling unit, the "optional" feeder or service load calculation method can be used instead of the standard method under which condition?

Single 120/240V or 208Y/120V service, 100A or more
Only for buildings with 3-phase power
Only for services under 60 amperes
It can never be used for dwellings

NEC Reference: NEC 220.82

Question 27: An underground service raceway enters a building. What does 230.8 require?

A drip loop at the entry
Sealing or plugging the raceway at either or both ends
Leaving the raceway open to drain
Filling the raceway with sand

NEC Reference: NEC 230.8

Question 28: What must the rating of the service disconnecting means be at least?

The calculated load to be carried, determined per Article 220
The utility transformer rating
The size of the meter base
The rating of the largest branch circuit

NEC Reference: NEC 230.79

Question 29: A two-family dwelling has an individually metered feeder to each unit. On what load is each unit's feeder sized?

Half of the whole building load
The service rating of the building
That unit's own calculated load
The largest appliance in the building

NEC Reference: NEC 220.40

Question 30: How must listed service equipment be installed?

In any way that fits the space
With extra fasteners only
As the inspector decides on site
In accordance with its listing and labeling instructions

NEC Reference: NEC 110.3(B)

Key NEC References for This Test

Article	What It Covers
Ch. 1–4	General rules — apply to all installations
Ch. 5–7	Special rules — override Ch. 1–4 where they conflict
Ch. 8	Communications — completely independent of Ch. 1–7
Ch. 9	Tables — referenced by articles, not standalone enforceable rules
Art. 210.12	AFCI — major expansion in NEC 2026
Art. 230.67	Surge protection at service equipment — new NEC 2026

Study Tip: Learn the NEC index — use keywords, not article numbers. Practice finding 5 different topics in under 2 minutes each.

Service Entrance, Branch Circuits & Feeder Conductors 2 — NEC 2020 Edition

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Service Entrance, Branch Circuits & Feeder Conductors 2 — NEC 2020 Edition — Question List

Question 1: A feeder supplies 60 A of continuous load and 30 A of noncontinuous load. What is the minimum standard overcurrent device rating?

Question 2: A dwelling unit has a general lighting connected load of 4,000 VA. What is the total demand load after applying the lighting demand factor?

Question 3: What is the branch-circuit load calculated for a show window that is 10 feet wide?

Question 4: How many 15-ampere, 14 AWG branch circuits are minimally required to supply the general lighting load for a 2,000 sq ft dwelling unit at 120 volts?

Question 5: A retail shop has 20 duplex receptacles, each on its own yoke. What is the calculated load for these receptacles?

Question 6: In a shopping complex, what is the maximum number of receptacles generally permitted on a 20-ampere, 120-volt breaker, using the standard 180 VA per receptacle?

Question 7: A single piece of equipment has five receptacles built into it. What is the total calculated load for these receptacles?

Question 8: A 1,200 sq ft dwelling unit is supplied at 120/240 V. What is the minimum number of 15-ampere, 2-wire general lighting branch circuits?

Question 9: What is the minimum laundry circuit load that must be considered for each 2-wire laundry branch circuit in a dwelling unit?

Question 10: For sizing a feeder or service neutral, how is the maximum unbalanced load defined?

Question 11: What is the maximum number of service disconnecting means permitted for one service, grouped at one location?

Question 12: For a one-family dwelling, what is the minimum rating required for the service disconnecting means?

Question 13: What is the general minimum vertical clearance of overhead service conductors above a roof surface?

Question 14: A service mast supports the service-drop conductors. What must it be?

Question 15: What is the general minimum size of underground service-lateral conductors?

Question 16: Per the NEC informational note, what is the recommended maximum COMBINED voltage drop for a feeder plus branch circuit together?

Question 17: Service-entrance cable is subject to physical damage. Which method may protect it?

Question 18: How must each service disconnecting means be marked?

Question 19: Where must the service disconnecting means be installed?

Question 20: For a grounded service, where may the grounding electrode conductor connect to the grounded service conductor?

Question 21: Under the 10-foot feeder tap rule, tap conductors not over 10 feet long must have an ampacity of not less than what?

Question 22: In a multiple-occupancy building, what access must each occupant have to service disconnecting means?

Question 23: Ungrounded service-entrance conductors must have an ampacity not less than what?

Question 24: Where must a service head be located?

Question 25: For service equipment rated 0-150 volts to ground under Condition 1, what is the minimum required clear working space depth?

Question 26: For a single dwelling unit, the "optional" feeder or service load calculation method can be used instead of the standard method under which condition?

Question 27: An underground service raceway enters a building. What does 230.8 require?

Question 28: What must the rating of the service disconnecting means be at least?

Question 29: A two-family dwelling has an individually metered feeder to each unit. On what load is each unit's feeder sized?

Question 30: How must listed service equipment be installed?

Key NEC References for This Test

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