NEBOSH Certificate in Electrical Safety
Practice Examination Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of earthing in an electrical installation?
A. To increase voltage
B. To reduce energy consumption
C. To provide a safe path for fault current
D. To stabilize frequency
Earthing provides a low-resistance path for fault current, reducing the risk
of electric shock and fire.
2. Which factor most influences the severity of electric shock?
A. Wire color
B. Ambient temperature
, C. Magnitude of current through the body
D. Type of insulation
The amount of current passing through the body determines the
physiological effect and potential lethality.
3. What device is primarily used to protect against overload current?
A. RCD
B. Fuse
C. Transformer
D. Capacitor
A fuse interrupts excessive current flow caused by overloads or short
circuits.
4. Which regulation requires isolation before electrical maintenance
work?
A. Manual handling regulation
B. PPE regulation
C. Electricity at Work Regulations
D. Fire safety order
The Electricity at Work Regulations require systems to be made dead
before work begins where possible.
, 5. What is the typical safe extra-low voltage (SELV) limit in dry
conditions?
A. 12 V
B. 50 V AC
C. 110 V
D. 240 V
SELV is typically limited to 50 V AC in dry conditions to reduce shock risk.
6. Which class of fire involves energized electrical equipment?
A. Class A
B. Class B
C. Class C
D. Class E (Electrical)
Electrical fires involve energized equipment and require non-conductive
extinguishing methods.
7. What is the function of a residual current device (RCD)?
A. Increase current flow
B. Reduce voltage
C. Detect imbalance between live and neutral currents
D. Store electrical charge
An RCD trips when it detects leakage current, preventing electric shock.
, 8. Which of the following increases electrical resistance in the human
body?
A. Wet skin
B. Metal contact
C. Dry skin
D. Sweating
Dry skin has higher resistance, reducing current flow compared to wet skin.
9. The main hazard from overhead power lines is:
A. Noise
B. Electric shock and arcing
C. Dust
D. Heat only
Contact or proximity can cause arcing and fatal electric shock.
10. What is lockout/tagout primarily intended to prevent?
A. Equipment overheating
B. Unexpected energization
C. Voltage drop
D. Static build-up
Practice Examination Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of earthing in an electrical installation?
A. To increase voltage
B. To reduce energy consumption
C. To provide a safe path for fault current
D. To stabilize frequency
Earthing provides a low-resistance path for fault current, reducing the risk
of electric shock and fire.
2. Which factor most influences the severity of electric shock?
A. Wire color
B. Ambient temperature
, C. Magnitude of current through the body
D. Type of insulation
The amount of current passing through the body determines the
physiological effect and potential lethality.
3. What device is primarily used to protect against overload current?
A. RCD
B. Fuse
C. Transformer
D. Capacitor
A fuse interrupts excessive current flow caused by overloads or short
circuits.
4. Which regulation requires isolation before electrical maintenance
work?
A. Manual handling regulation
B. PPE regulation
C. Electricity at Work Regulations
D. Fire safety order
The Electricity at Work Regulations require systems to be made dead
before work begins where possible.
, 5. What is the typical safe extra-low voltage (SELV) limit in dry
conditions?
A. 12 V
B. 50 V AC
C. 110 V
D. 240 V
SELV is typically limited to 50 V AC in dry conditions to reduce shock risk.
6. Which class of fire involves energized electrical equipment?
A. Class A
B. Class B
C. Class C
D. Class E (Electrical)
Electrical fires involve energized equipment and require non-conductive
extinguishing methods.
7. What is the function of a residual current device (RCD)?
A. Increase current flow
B. Reduce voltage
C. Detect imbalance between live and neutral currents
D. Store electrical charge
An RCD trips when it detects leakage current, preventing electric shock.
, 8. Which of the following increases electrical resistance in the human
body?
A. Wet skin
B. Metal contact
C. Dry skin
D. Sweating
Dry skin has higher resistance, reducing current flow compared to wet skin.
9. The main hazard from overhead power lines is:
A. Noise
B. Electric shock and arcing
C. Dust
D. Heat only
Contact or proximity can cause arcing and fatal electric shock.
10. What is lockout/tagout primarily intended to prevent?
A. Equipment overheating
B. Unexpected energization
C. Voltage drop
D. Static build-up
