Electrical Safety Flashcards
7 cards from real CSCS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Safety flashcards as text
Why is 110V preferred over 230V for portable tools on construction sites?
Answer: The centre-tapped earth system limits maximum shock voltage to 55V, greatly reducing the risk of a fatal shock
In a 110V CTE system the midpoint of the transformer secondary is earthed, so the maximum voltage to earth at either conductor is only 55V, significantly reducing electrocution risk.
What does a Residual Current Device (RCD) do?
Answer: Detects an imbalance caused by an earth fault and rapidly disconnects the power supply
An RCD continuously monitors the current balance between live and neutral conductors; any leakage to earth triggers a near-instant disconnection, protecting against electric shock.
Which of the following is a visual warning sign that electrical equipment may be unsafe to use?
Answer: The outer casing is cracked or has pieces broken away
A cracked or broken casing can expose live internal components, creating a direct electrocution hazard for the user.
Who is qualified to carry out repairs on electrical equipment or installations on a construction site?
Answer: A competent electrician with the relevant training and qualifications
Only a competent electrician with appropriate training, knowledge, and experience should perform electrical repairs to ensure the work is carried out safely and correctly.
What is the primary function of the earth wire in an electrical circuit?
Answer: To provide a low-resistance fault path so protective devices operate and disconnect the supply
The earth wire (green and yellow) provides a safe fault-current path that causes fuses or circuit breakers to operate, removing the dangerous voltage before a person can be shocked.
What steps should be taken before excavating in an area where underground electrical cables may be present?
Answer: Obtain service drawings, use a Cable Avoidance Tool (CAT), and follow safe digging procedures
Service drawings locate known cables on paper, a CAT scanner detects live cables by their electromagnetic field, and safe digging procedures ensure workers avoid striking buried services.
Which specialist tool is used to detect the electromagnetic field emitted by buried electrical cables before excavation?
Answer: A Cable Avoidance Tool (CAT)
A Cable Avoidance Tool (CAT) is purpose-built to detect the electromagnetic field radiated by live cables, allowing workers to locate and avoid them during excavation.