APPRENTICE LINEMAN GENERAL KNOWLEDGE EXAM QUESTIONS
WITH ANSWERS 2025/2026 GRADED A+
A device used to convert AC power from one combination of voltage and current to
another is called a __________ ? - transformer
The sheet iron core form a closed: - magnetic circuit
How are the primary and secondary windings of a transformer coupled? - magnetically
What is the formula for number of windings to voltage? - voltage primary/voltage
secondary = number of turns primary/number of turns secondary
What destroys transformers in an overload situation? - heat
The purpose of oil in a transformer is: - cool and insulate the coils
What keeps a transformer from acting as a short circuit? - Counter voltage (aka: back
voltage, CEMF)
What is usually the maximum temperature the insulation in a transformer can stand? -
221° F (105° C)
Why are underground transformers and their bushings hermetically sealed? - To guard
against moisture damage.
What does a CSP transformer have that a conventional does not? - 1. Primary lightning
arrestor
2. Primary protective fuse link
3. Overcurrent protection on secondary
4. Overload Signal lamp
5. External Operating handle for opening and closing secondary
6. No load tap changer
What is the formula for resistivity of a wire? - R = (K x L) ÷ A
Where: R = resistance
K = specific resistance
L = length of wire in feet
A = circular mil area
What are the specific resistance's of copper and aluminum? - Copper (Cu) 10.4
Aluminum (Al) 17.0
What is specific resistivity? - The resistance of a wire one mil in diameter one foot long.
A generator with only two slip rings is know as a: - A single phase generator (alternating
current).
,A generator equipped with a commutator delivers __________ current. - direct
What is the equivalent resistance in a magnetic circuit? - reluctance
What term represents the amount of current multiplied by the specific coil? - Ampere-
turns
Name three methods used to cool transformers? - 1. Oil
2. Air
3. Water
How many herts are used in AC in the United States? - 60
What are two types of instrument transformers? - Current & Potential
Transformers of less that 500kV are called __________ transformers. - distribution
Transformers of 500kV and larger are known as __________ transformers. - power
How many windings does an auto-transformer have? - 1
What ratio does an auto transformer usually have? - 2:1
Primary metering requires both __________ transformers and __________
transformers. - potential, current
Current transformers are connected in __________ with the load. - series
In a large-sized generator which conductors spin and which remain stationary? - The
armature conductors are stationary and the poles revolve.
What should be done to rubber gloves each time they are used? - Visually inspected, air
tested, check for proper voltage (dielectric strength), check for ozone cutting and
mechanical damage.
What current are constant current transformers usually fixed at? - 6.6 amps
Which winding on a constant current transformer is moveable, primary or secondary? -
secondary
What moves the windings apart on a constant current transformer? - magnetic repulsion
What type of series street light circuit uses only one wire? - open loop
Why is filler paste injected into the sleeve? - To prevent oxidation to the splice.
, Name four ways that electric shock may effect the human body? - 1. Asphyxia
2. Burns
3. Fibrillation
4. Muscle Spasm
What precaution must be taken when freeing a victim from energized lines? - That is is
deenergized
Which way does electric current flow? - negative to positive (Electron Current Flow)
...older texts used Conventional Current Flow (positive to negative) aka: Hole Flow,
Positive Current Flow
Earth resistance is largely determined by what two conditions? - 1. Chemical ingredients
in the soil
2. Moisture present
__________ percent of the resistance surrounding an electrode is within a radius of 6'
to 10' from an electrode. - 90
Ground rods should be long enough to reach __________ moisture level of the soil? -
permanent
Codes require that the resistance of a driven ground shall not exceed __________
ohms. - 25
Grounds for lightning arrestors should be __________ than 25 ohms. - less
What are the two types of counterpoise grounding? - 1. Continuos (parallel)
2. Crowfoot (radial)
List two methods to test that the line is dead before installing protective grounds? - 1.
High voltage volt meter
2. Fuzzing
What does a good ground require? - 1. Low resistance path to ground
2. Clean tight connections made at proper points
3. Adequate current-carrying capacity of grounding equipment.
Where will the primary fuse on a CSP be located? - Inside the tank between the primary
coil and the primary bushing.
The overcurrent protective device on a CSP transformer is located where? - On the
secondary side inside the tank between the secondary bushing and the secondary coil.
WITH ANSWERS 2025/2026 GRADED A+
A device used to convert AC power from one combination of voltage and current to
another is called a __________ ? - transformer
The sheet iron core form a closed: - magnetic circuit
How are the primary and secondary windings of a transformer coupled? - magnetically
What is the formula for number of windings to voltage? - voltage primary/voltage
secondary = number of turns primary/number of turns secondary
What destroys transformers in an overload situation? - heat
The purpose of oil in a transformer is: - cool and insulate the coils
What keeps a transformer from acting as a short circuit? - Counter voltage (aka: back
voltage, CEMF)
What is usually the maximum temperature the insulation in a transformer can stand? -
221° F (105° C)
Why are underground transformers and their bushings hermetically sealed? - To guard
against moisture damage.
What does a CSP transformer have that a conventional does not? - 1. Primary lightning
arrestor
2. Primary protective fuse link
3. Overcurrent protection on secondary
4. Overload Signal lamp
5. External Operating handle for opening and closing secondary
6. No load tap changer
What is the formula for resistivity of a wire? - R = (K x L) ÷ A
Where: R = resistance
K = specific resistance
L = length of wire in feet
A = circular mil area
What are the specific resistance's of copper and aluminum? - Copper (Cu) 10.4
Aluminum (Al) 17.0
What is specific resistivity? - The resistance of a wire one mil in diameter one foot long.
A generator with only two slip rings is know as a: - A single phase generator (alternating
current).
,A generator equipped with a commutator delivers __________ current. - direct
What is the equivalent resistance in a magnetic circuit? - reluctance
What term represents the amount of current multiplied by the specific coil? - Ampere-
turns
Name three methods used to cool transformers? - 1. Oil
2. Air
3. Water
How many herts are used in AC in the United States? - 60
What are two types of instrument transformers? - Current & Potential
Transformers of less that 500kV are called __________ transformers. - distribution
Transformers of 500kV and larger are known as __________ transformers. - power
How many windings does an auto-transformer have? - 1
What ratio does an auto transformer usually have? - 2:1
Primary metering requires both __________ transformers and __________
transformers. - potential, current
Current transformers are connected in __________ with the load. - series
In a large-sized generator which conductors spin and which remain stationary? - The
armature conductors are stationary and the poles revolve.
What should be done to rubber gloves each time they are used? - Visually inspected, air
tested, check for proper voltage (dielectric strength), check for ozone cutting and
mechanical damage.
What current are constant current transformers usually fixed at? - 6.6 amps
Which winding on a constant current transformer is moveable, primary or secondary? -
secondary
What moves the windings apart on a constant current transformer? - magnetic repulsion
What type of series street light circuit uses only one wire? - open loop
Why is filler paste injected into the sleeve? - To prevent oxidation to the splice.
, Name four ways that electric shock may effect the human body? - 1. Asphyxia
2. Burns
3. Fibrillation
4. Muscle Spasm
What precaution must be taken when freeing a victim from energized lines? - That is is
deenergized
Which way does electric current flow? - negative to positive (Electron Current Flow)
...older texts used Conventional Current Flow (positive to negative) aka: Hole Flow,
Positive Current Flow
Earth resistance is largely determined by what two conditions? - 1. Chemical ingredients
in the soil
2. Moisture present
__________ percent of the resistance surrounding an electrode is within a radius of 6'
to 10' from an electrode. - 90
Ground rods should be long enough to reach __________ moisture level of the soil? -
permanent
Codes require that the resistance of a driven ground shall not exceed __________
ohms. - 25
Grounds for lightning arrestors should be __________ than 25 ohms. - less
What are the two types of counterpoise grounding? - 1. Continuos (parallel)
2. Crowfoot (radial)
List two methods to test that the line is dead before installing protective grounds? - 1.
High voltage volt meter
2. Fuzzing
What does a good ground require? - 1. Low resistance path to ground
2. Clean tight connections made at proper points
3. Adequate current-carrying capacity of grounding equipment.
Where will the primary fuse on a CSP be located? - Inside the tank between the primary
coil and the primary bushing.
The overcurrent protective device on a CSP transformer is located where? - On the
secondary side inside the tank between the secondary bushing and the secondary coil.
