CITB CITB Electrical and Mechanical Systems 1 — Questions and Answers
Question 1: What is the maximum voltage classified as 'low voltage' under US electrical standards used on construction sites?
- 110V
- 440V
- 1000V (Correct answer)
- 50V
Correct answer: 1000V
Under IEC and US construction site standards, low voltage is defined as up to 1000V AC or 1500V DC.
Question 2: Which color identifies the ground (earth) wire in US construction site wiring?
- White
- Black
- Green or bare copper (Correct answer)
- Red
Correct answer: Green or bare copper
In US wiring, the ground wire is identified by green insulation or bare copper conductor.
Question 3: What does GFCI stand for in the context of construction site electrical safety?
- Ground Fault Circuit Interrupter (Correct answer)
- General Fuse Circuit Insulator
- Grounded Fixed Current Indicator
- Ground Frequency Control Interface
Correct answer: Ground Fault Circuit Interrupter
A Ground Fault Circuit Interrupter (GFCI) detects imbalances in electrical current and shuts off power to prevent electrocution.
Question 4: Under CITB guidance, who is responsible for inspecting temporary electrical installations on a construction site?
- Any site worker
- A competent electrician (Correct answer)
- The project manager only
- The site client
Correct answer: A competent electrician
Only a competent electrician with the appropriate qualifications should inspect and certify temporary electrical installations.
Question 5: What is the purpose of a Permit to Work (PTW) system for mechanical systems on a construction site?
- To log overtime hours
- To authorize and control high-risk maintenance work safely (Correct answer)
- To schedule material deliveries
- To record plant fuel usage
Correct answer: To authorize and control high-risk maintenance work safely
A Permit to Work system formally authorizes high-risk tasks such as working on pressurized or energized mechanical systems, ensuring safety controls are in place.
Question 6: Which procedure ensures a mechanical system cannot be accidentally energized while workers are servicing it?
- Toolbox talk
- Lockout/Tagout (LOTO) (Correct answer)
- Risk assessment
- Method statement
Correct answer: Lockout/Tagout (LOTO)
Lockout/Tagout (LOTO) physically locks energy isolation points and tags them to prevent accidental re-energization during maintenance.
CITB CITB Electrical and Mechanical Systems 1
What is the maximum voltage classified as 'low voltage' under US electrical standards used on construction sites?