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Branch Circuit & Feeder Requirements — ICC E1 Practice Questions

34 questions · 28% of the ICC E1 exam

Worked questions

1. A 120/240V single-phase service to a two-family dwelling is provided with a 200A main disconnect. What is the minimum required overcurrent protection for the 120V branch circuits?

  • A100A
  • 125A
  • C150A
  • D175A

Exam tip

Always calculate the minimum required protection based on the service rating.

Why B is correct

According to 2024 IRC 210.8(A), the branch circuit overcurrent protection must not be less than 125% of the service rating. For a 200A service, the minimum required protection is 125A (200A x 1.25). Option A is incorrect as it is below the required 125%. Options C and D are also incorrect as they exceed the minimum requirement.

2. A 30-ampere branch circuit is being installed to serve a clothes dryer. What is the minimum size of the overcurrent protection device required for this circuit?

  • A15-ampere
  • B20-ampere
  • C30-ampere
  • 40-ampere

Exam tip

Ensure that the overcurrent protection device matches the rating of the branch circuit for appliances.

Why D is correct

According to 2024 IRC 210.11(B), the overcurrent protection device for a clothes dryer circuit must be no less than the rating of the branch circuit. Since the branch circuit is 30-ampere, the protection device must also be 30-ampere.

5. A remodeler is planning to install a new 20-ampere branch circuit to serve a bathroom. The existing electrical panel has a 100-ampere main service. What is the maximum number of additional 20-ampere circuits that can be added?

  • A1
  • 2
  • C3
  • D4

Exam tip

Always check the existing load and the panel's rated capacity before adding new circuits.

Why B is correct

According to 2024 IRC 210.8(B), the total number of branch circuits in a panel cannot exceed 80% of the panel's rated capacity. Since the panel is 100-ampere, 80% is 80-ampere, leaving 20-ampere available for additional circuits. Therefore, two 20-ampere circuits can be added.

6. What is the minimum requirement for GFCI protection in a kitchen countertop circuit?

  • AA single GFCI-protected receptacle
  • A GFCI-protected circuit for all countertop outlets
  • CNo GFCI protection required
  • DA GFCI-protected circuit for all kitchen outlets

Exam tip

Always ensure that kitchen countertop circuits are GFCI-protected.

Why B is correct

According to 2023 NEC 210.8(A), all countertop outlets in a kitchen must be on a GFCI-protected circuit.

28 more in the bank

Answers and explanations for these are in the app.

  • A 120/240V, 200A main service panel is installed in a single-family dwelling. The dwelling has a detached garage. What is the minimum size of the feeder required to supply the garage?
  • A 120/240V, 200A main service panel is installed in a single-family dwelling. Which type of overcurrent protection device is required for the 20A branch circuit supplying the kitchen countertop outlets?
  • A 120/240V, 30A branch circuit is being installed to supply a laundry room. Which type of overcurrent protection device is required for this circuit?
  • A 120/240V single-phase residential dwelling has a 200A main service. What is the minimum size of the main disconnecting means required?
  • A 20-ampere branch circuit is being installed to serve a kitchen countertop receptacle. What is the minimum size of the overcurrent protection device required for this circuit?
  • A kitchen remodel requires the addition of a new 20A branch circuit. What size overcurrent protection device is required for this circuit?
  • A new 15A branch circuit is required for a bathroom. Which type of overcurrent protection device is required for this circuit?
  • A new 20A branch circuit is required for a garage workshop. The garage is located in an attached accessory building. Which type of overcurrent protection device is required for this circuit?
  • A new residential service panel is being installed. What is the minimum number of spaces required for the main disconnect, according to 2023 NEC 230.42(A)?
  • A new subdivision requires a 400A feeder to supply electrical service to multiple homes. What is the minimum size of the conductor required for the feeder, according to 2024 IRC 310.8(A)?
  • A remodeler is planning to install a new 15-ampere branch circuit to serve a kitchen appliance. The existing electrical panel is already at 80% of its rated capacity. What is the maximum number of additional 15-ampere circuits that can be added?
  • A remodeling project involves the addition of a new kitchen appliance that requires a dedicated 20A branch circuit. What is the minimum size of the conductor required for the branch circuit, according to 2023 NEC 210.11(A)?
  • A renovation project requires the replacement of a 100A feeder serving a kitchen. The kitchen is equipped with modern appliances that may draw up to 150A. What is the minimum size of the new feeder required?
  • A residential addition requires the installation of a new 20A branch circuit. What is the maximum length of the branch circuit, according to 2023 NEC 210.52(C)?
  • A residential building has a 100-ampere main service. What is the maximum length of a feeder conductor that can be used to supply a 120/240V, 100-ampere subpanel?
  • A residential building has a 200-ampere main service. What is the minimum size of the feeder conductors required to supply a 120/240V, 200-ampere subpanel located 100 feet away?
  • A residential building has a 200-ampere main service. What is the minimum size of the grounding electrode conductor required to connect the service panel to the grounding electrode?
  • A residential building has a 200A main service. The existing 100A feeder supplying the second floor has been identified as overloaded. What is the minimum size of the new feeder required to safely supply the second floor?
  • A residential building has a 200A main service. The existing 150A feeder supplying the basement has been identified as overloaded. What is the minimum size of the new feeder required to safely supply the basement?
  • A residential building has an existing grounding electrode system that is in poor condition. What is the minimum length of the grounding electrode conductor required to be installed as per 2023 NEC 250.66(C)?
  • A residential building is being constructed with a total of 10 branch circuits for lighting and receptacles. The electrical system is designed for 120/240V single phase and is capable of handling up to 400A. Which of the following is the correct calculation for the minimum size of the feeder cable required for these branch circuits?
  • A two-family dwelling has a 200A main service. What is the minimum number of branch circuits required for the first floor?
  • During an inspection, you find that the grounding electrode conductor is not securely connected to the grounding electrode. What action should you take?
  • During the inspection of an existing residential building, you find that the kitchen area has been expanded, and an additional 20A dedicated circuit is required for the new appliances. The existing electrical panel is rated for 200A and has 6 dedicated circuits. Which of the following actions should be taken to safely accommodate the new circuit?
  • In a residential outdoor area, what is the minimum requirement for GFCI protection, according to 2023 NEC 210.8(A)?
  • Which of the following is the correct method for grounding a service panel in a residential building?
  • Which of the following locations is exempt from the requirement for an arc-fault circuit interrupter (AFCI) protection, according to 2023 NEC 210.12(A)(1)?
  • You find that a circuit breaker in a residential dwelling has a trip indicator that is not functioning properly. What should you do?

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