EWRB THEORY CORE EXAM TEST 2026 QUESTIONS AND
SOLUTIONS RATED A+
earth conductor may be at a different potential.
✔✔What are the effects of voltage on the severity of an electric shock? - ✔✔Higher
voltage increases the current that flows through the body, making the shock more
severe.
✔✔How does the duration of contact with electricity affect the severity of a shock? -
✔✔The longer the contact, the more current flows through the body, increasing the
severity of the shock and potential injury.
✔✔How does wet or punctured skin affect the severity of an electric shock? - ✔✔Wet or
punctured skin reduces resistance to electrical current, allowing more current to flow
through the body, which can increase the severity of the shock.
✔✔What is the primary factor that determines the severity of an electric shock? -
✔✔The amount of current that flows through the body is the primary factor in
determining the severity of an electric shock.
✔✔How does skin condition (dry vs. wet) influence electric shock severity? - ✔✔Wet
skin offers less resistance to electrical current, allowing more current to pass through
the body, making the shock more severe.
✔✔Why is the current through the heart dangerous during an electric shock? - ✔✔If
electric current flows through the heart, it can disrupt its normal rhythm, potentially
leading to fatal arrhythmias or cardiac arrest.
✔✔What type of fire extinguisher is suitable for electrical fires? - ✔✔Carbon dioxide
(CO₂) extinguishers, Class F (wet chemical), Class ABC (dry powder), and Class D
(metal fires) extinguishers are suitable for electrical fires.
✔✔How does a Carbon Dioxide (CO₂) fire extinguisher work on electrical fires? - ✔✔It
works by displacing oxygen around the fire, smothering it, and it is non-conductive,
making it safe for electrical fires in equipment like computers and machinery.
✔✔When should you use a Class F (wet chemical) fire extinguisher? - ✔✔Class F
extinguishers are ideal for electrical fires in cooking appliances (like deep fryers) but can
also be used for electrical fires in other equipment. The wet chemical cools and
prevents re-ignition.
✔✔Can a Class ABC (dry powder) fire extinguisher be used on electrical fires? -
✔✔Yes, it can. It works by smothering the fire and interrupting the chemical reaction,
, but should be used with caution around sensitive electronics due to the powder's
potential damage.
✔✔What is the role of dry powder in a Class ABC fire extinguisher for electrical fires? -
✔✔The dry powder smothers the fire and interrupts the chemical reaction, but it is
important to be cautious in confined spaces as it can cause damage to electronic
equipment.
✔✔What type of fire extinguisher should be used for fires involving reactive metals in
electrical equipment? - ✔✔Class D fire extinguishers, which use dry powder specifically
for metal fires, should be used for electrical fires involving metals like magnesium or
aluminum.
✔✔Why should water-based fire extinguishers never be used on electrical fires? -
✔✔Water is a conductor of electricity, so using a water-based extinguisher on an
electrical fire can cause electrocution and worsen the fire.
✔✔What safety precaution should be taken before using a fire extinguisher on an
electrical fire? - ✔✔Ensure the power source is turned off (if safe to do so) before
attempting to extinguish the fire, and use an appropriate, non-conductive extinguisher
(e.g., CO₂ or dry powder).
✔✔What is the formula for voltage ratio in a transformer? - ✔✔V1/V2 = N1/N2 where V1
and V2 are the primary and secondary voltages, and N1 and N2 are the primary and
secondary number of turns
✔✔What is the formula for current ratio in a transformer? - ✔✔I1/I2 = N2/N1, where I1
and I2 are the primary and secondary currents
✔✔What is the formula for calculating the kVA rating of a transformer? - ✔✔kVa = V1 x
I , where V1 is the primary voltage and I1 is the primary current
✔✔How do you calculate the secondary voltage in a transformer? - ✔✔Using the
voltage ratio formula V1/V2 = N1/N2 , solve for V2
✔✔How do you calculate the secondary current in a transformer? - ✔✔Using the current
ratio formula: I1/I2 = N2/N1 , solve for I2
✔✔What is the relationship between voltage, current, and power in a transformer? -
✔✔V1 x I1 = V2 x I2, meaning power is constant (neglecting losses)
✔✔ What does the MEN system stand for? - ✔✔Multiple Earthed Neutral
SOLUTIONS RATED A+
earth conductor may be at a different potential.
✔✔What are the effects of voltage on the severity of an electric shock? - ✔✔Higher
voltage increases the current that flows through the body, making the shock more
severe.
✔✔How does the duration of contact with electricity affect the severity of a shock? -
✔✔The longer the contact, the more current flows through the body, increasing the
severity of the shock and potential injury.
✔✔How does wet or punctured skin affect the severity of an electric shock? - ✔✔Wet or
punctured skin reduces resistance to electrical current, allowing more current to flow
through the body, which can increase the severity of the shock.
✔✔What is the primary factor that determines the severity of an electric shock? -
✔✔The amount of current that flows through the body is the primary factor in
determining the severity of an electric shock.
✔✔How does skin condition (dry vs. wet) influence electric shock severity? - ✔✔Wet
skin offers less resistance to electrical current, allowing more current to pass through
the body, making the shock more severe.
✔✔Why is the current through the heart dangerous during an electric shock? - ✔✔If
electric current flows through the heart, it can disrupt its normal rhythm, potentially
leading to fatal arrhythmias or cardiac arrest.
✔✔What type of fire extinguisher is suitable for electrical fires? - ✔✔Carbon dioxide
(CO₂) extinguishers, Class F (wet chemical), Class ABC (dry powder), and Class D
(metal fires) extinguishers are suitable for electrical fires.
✔✔How does a Carbon Dioxide (CO₂) fire extinguisher work on electrical fires? - ✔✔It
works by displacing oxygen around the fire, smothering it, and it is non-conductive,
making it safe for electrical fires in equipment like computers and machinery.
✔✔When should you use a Class F (wet chemical) fire extinguisher? - ✔✔Class F
extinguishers are ideal for electrical fires in cooking appliances (like deep fryers) but can
also be used for electrical fires in other equipment. The wet chemical cools and
prevents re-ignition.
✔✔Can a Class ABC (dry powder) fire extinguisher be used on electrical fires? -
✔✔Yes, it can. It works by smothering the fire and interrupting the chemical reaction,
, but should be used with caution around sensitive electronics due to the powder's
potential damage.
✔✔What is the role of dry powder in a Class ABC fire extinguisher for electrical fires? -
✔✔The dry powder smothers the fire and interrupts the chemical reaction, but it is
important to be cautious in confined spaces as it can cause damage to electronic
equipment.
✔✔What type of fire extinguisher should be used for fires involving reactive metals in
electrical equipment? - ✔✔Class D fire extinguishers, which use dry powder specifically
for metal fires, should be used for electrical fires involving metals like magnesium or
aluminum.
✔✔Why should water-based fire extinguishers never be used on electrical fires? -
✔✔Water is a conductor of electricity, so using a water-based extinguisher on an
electrical fire can cause electrocution and worsen the fire.
✔✔What safety precaution should be taken before using a fire extinguisher on an
electrical fire? - ✔✔Ensure the power source is turned off (if safe to do so) before
attempting to extinguish the fire, and use an appropriate, non-conductive extinguisher
(e.g., CO₂ or dry powder).
✔✔What is the formula for voltage ratio in a transformer? - ✔✔V1/V2 = N1/N2 where V1
and V2 are the primary and secondary voltages, and N1 and N2 are the primary and
secondary number of turns
✔✔What is the formula for current ratio in a transformer? - ✔✔I1/I2 = N2/N1, where I1
and I2 are the primary and secondary currents
✔✔What is the formula for calculating the kVA rating of a transformer? - ✔✔kVa = V1 x
I , where V1 is the primary voltage and I1 is the primary current
✔✔How do you calculate the secondary voltage in a transformer? - ✔✔Using the
voltage ratio formula V1/V2 = N1/N2 , solve for V2
✔✔How do you calculate the secondary current in a transformer? - ✔✔Using the current
ratio formula: I1/I2 = N2/N1 , solve for I2
✔✔What is the relationship between voltage, current, and power in a transformer? -
✔✔V1 x I1 = V2 x I2, meaning power is constant (neglecting losses)
✔✔ What does the MEN system stand for? - ✔✔Multiple Earthed Neutral
