NEC Article 100 – Definitions: 100
Practice Questions & Detailed
Answers
This comprehensive practice exam covers essential definitions from Article 100 of the
National Electrical Code, including 2026 updates. Each question is followed by a detailed
rationale explaining the correct answer and why the other options are incorrect.
NEW 2026 DEFINITIONS (Questions 1-20)
1. According to the 2026 NEC, which of the following best defines a "Line-
toGround" reference?
A) An electrical reference between two current-carrying conductors in a circuit
B) An electrical reference between a current-carrying conductor, other than a neutral
conductor, and an equipment grounding conductor, grounded equipment, or ground
C) An electrical reference between a current-carrying conductor and a neutral conductor
D) An electrical reference between two grounded conductors
Correct Resolution Result Verified Answers : B
Rationale: The 2026 NEC defines Line-to-Ground as "an electrical reference between
a current-carrying conductor other than a neutral conductor and an equipment
grounding conductor, grounded equipment, or ground." This new definition eliminates
ambiguity in voltage references across both AC and DC systems .
Why Others Are Incorrect:
• A describes Line-to-Line
• C describes Line-to-Neutral
, • D is not a defined term in the NEC
2. Which of the following best defines "Line-to-Line" according to the 2026 NEC?
A) An electrical reference between a current-carrying conductor and ground
B) An electrical reference between a current-carrying conductor and a neutral conductor
C) An electrical reference between two current-carrying conductors in a circuit other
than a neutral conductor
D) An electrical reference between two grounded conductors
Correct Resolution Result Verified Answers : C
Rationale: Line-to-Line is defined as "an electrical reference between two
currentcarrying conductors in a circuit other than a neutral conductor." This definition
applies universally to both AC and DC systems .
Why Others Are Incorrect:
• A describes Line-to-Ground
• B describes Line-to-Neutral
• D is not a defined term
3. The 2026 NEC defines "Line-to-Neutral" as an electrical reference between:
A) Two current-carrying conductors in a circuit
B) A current-carrying conductor, other than a neutral conductor, and a neutral
conductor or neutral point in a circuit
C) A current-carrying conductor and ground
D) A neutral conductor and an equipment grounding conductor
,Correct Resolution Result Verified Answers : B
Rationale: Line-to-Neutral is defined as "an electrical reference between a
currentcarrying conductor, other than a neutral conductor, and a neutral conductor or
neutral point in a circuit." These new definitions provide clarity across all supply system
types .
4. What is the primary reason these new Line-to-Ground, Line-to-Line, and Line-
toNeutral definitions were added to the 2026 NEC?
A) To eliminate ambiguity in voltage references across both AC and DC systems
B) To replace existing definitions that were removed
C) To make the NEC longer and more complex
D) To eliminate the need for training manuals
Correct Resolution Result Verified Answers : A
Rationale: The 2026 NEC introduces these three new definitions to provide clarity for
commonly used phrases and eliminate ambiguity surrounding how the word "line" is
used throughout the Code. With the rise of DC systems (photovoltaic, energy storage,
etc.), there is a growing need for terms that apply universally without guesswork .
5. The new definitions for Line-to-Ground, Line-to-Line, and Line-to-Neutral are
important because they:
A) Only apply to AC systems
B) Create a shared language across all supply system types—AC or DC, grounded or
ungrounded
C) Replace all previous voltage references in the NEC
, D) Only apply to residential installations
Correct Resolution Result Verified Answers : B
Rationale: These definitions create a shared language across all supply system types,
AC or DC, grounded or ungrounded. This means less confusion in design, installation,
inspection, and enforcement, making for safer, more reliable systems .
6. According to the 2026 NEC, what is the definition of a Power Control System
(PCS)?
A) Equipment that monitors and controls power within a system to prevent overload
B) Equipment that measures energy consumption for billing purposes
C) Equipment that generates power from renewable sources
D) Equipment that distributes power from a utility to a building
Correct Resolution Result Verified Answers : A
Rationale: A Power Control System (PCS) is defined as "equipment that monitors and
controls power within a system to prevent overload of an electrical service, conductor, or
power distribution equipment." This new definition reflects the growing complexity of
modern power systems .
7. A Multisource Power Control System (Multisource PCS) is defined as a type of
PCS with capability to:
A) Only perform load management
B) Control power production sources, with or without load management
C) Monitor power without controlling it
D) Replace all traditional circuit protection
Practice Questions & Detailed
Answers
This comprehensive practice exam covers essential definitions from Article 100 of the
National Electrical Code, including 2026 updates. Each question is followed by a detailed
rationale explaining the correct answer and why the other options are incorrect.
NEW 2026 DEFINITIONS (Questions 1-20)
1. According to the 2026 NEC, which of the following best defines a "Line-
toGround" reference?
A) An electrical reference between two current-carrying conductors in a circuit
B) An electrical reference between a current-carrying conductor, other than a neutral
conductor, and an equipment grounding conductor, grounded equipment, or ground
C) An electrical reference between a current-carrying conductor and a neutral conductor
D) An electrical reference between two grounded conductors
Correct Resolution Result Verified Answers : B
Rationale: The 2026 NEC defines Line-to-Ground as "an electrical reference between
a current-carrying conductor other than a neutral conductor and an equipment
grounding conductor, grounded equipment, or ground." This new definition eliminates
ambiguity in voltage references across both AC and DC systems .
Why Others Are Incorrect:
• A describes Line-to-Line
• C describes Line-to-Neutral
, • D is not a defined term in the NEC
2. Which of the following best defines "Line-to-Line" according to the 2026 NEC?
A) An electrical reference between a current-carrying conductor and ground
B) An electrical reference between a current-carrying conductor and a neutral conductor
C) An electrical reference between two current-carrying conductors in a circuit other
than a neutral conductor
D) An electrical reference between two grounded conductors
Correct Resolution Result Verified Answers : C
Rationale: Line-to-Line is defined as "an electrical reference between two
currentcarrying conductors in a circuit other than a neutral conductor." This definition
applies universally to both AC and DC systems .
Why Others Are Incorrect:
• A describes Line-to-Ground
• B describes Line-to-Neutral
• D is not a defined term
3. The 2026 NEC defines "Line-to-Neutral" as an electrical reference between:
A) Two current-carrying conductors in a circuit
B) A current-carrying conductor, other than a neutral conductor, and a neutral
conductor or neutral point in a circuit
C) A current-carrying conductor and ground
D) A neutral conductor and an equipment grounding conductor
,Correct Resolution Result Verified Answers : B
Rationale: Line-to-Neutral is defined as "an electrical reference between a
currentcarrying conductor, other than a neutral conductor, and a neutral conductor or
neutral point in a circuit." These new definitions provide clarity across all supply system
types .
4. What is the primary reason these new Line-to-Ground, Line-to-Line, and Line-
toNeutral definitions were added to the 2026 NEC?
A) To eliminate ambiguity in voltage references across both AC and DC systems
B) To replace existing definitions that were removed
C) To make the NEC longer and more complex
D) To eliminate the need for training manuals
Correct Resolution Result Verified Answers : A
Rationale: The 2026 NEC introduces these three new definitions to provide clarity for
commonly used phrases and eliminate ambiguity surrounding how the word "line" is
used throughout the Code. With the rise of DC systems (photovoltaic, energy storage,
etc.), there is a growing need for terms that apply universally without guesswork .
5. The new definitions for Line-to-Ground, Line-to-Line, and Line-to-Neutral are
important because they:
A) Only apply to AC systems
B) Create a shared language across all supply system types—AC or DC, grounded or
ungrounded
C) Replace all previous voltage references in the NEC
, D) Only apply to residential installations
Correct Resolution Result Verified Answers : B
Rationale: These definitions create a shared language across all supply system types,
AC or DC, grounded or ungrounded. This means less confusion in design, installation,
inspection, and enforcement, making for safer, more reliable systems .
6. According to the 2026 NEC, what is the definition of a Power Control System
(PCS)?
A) Equipment that monitors and controls power within a system to prevent overload
B) Equipment that measures energy consumption for billing purposes
C) Equipment that generates power from renewable sources
D) Equipment that distributes power from a utility to a building
Correct Resolution Result Verified Answers : A
Rationale: A Power Control System (PCS) is defined as "equipment that monitors and
controls power within a system to prevent overload of an electrical service, conductor, or
power distribution equipment." This new definition reflects the growing complexity of
modern power systems .
7. A Multisource Power Control System (Multisource PCS) is defined as a type of
PCS with capability to:
A) Only perform load management
B) Control power production sources, with or without load management
C) Monitor power without controlling it
D) Replace all traditional circuit protection
