NEBOSH Practice Test

What does "safe isolation" ensure regarding motive power sources?

1. They remain engaged during maintenance

2. They are allowed to operate continuously

3. They are disconnected securely by lockable means

4. They can be accessed easily without interruption

The correct answer is: They are disconnected securely by lockable means

Safe isolation is a crucial procedure used to ensure that all sources of motive power, such as electrical systems or machinery, are properly disconnected before maintenance or repair work begins. The primary purpose of safe isolation is to protect workers from accidental energization or movement while they are engaged in their tasks. The correct answer highlights that motive power sources are disconnected securely by lockable means. This method involves using locks and tags to prevent unauthorized or accidental reconnection of the power source during maintenance. It ensures that only individuals who are authorized and trained can restore the power after maintenance has been completed. This process is fundamental to ensuring worker safety, as it minimizes the risk of injury due to unexpected start-up or motion of machinery. In contrast, the other options present scenarios that could lead to unsafe working conditions. Maintaining engagement during maintenance (as mentioned in the first choice), allowing continuous operation (second choice), or easy access without interruption (fourth choice) could all expose workers to significant hazards related to moving parts, electrical shock, or other dangers associated with live equipment. Therefore, the concept of safe isolation focuses on creating a secure environment by ensuring disconnection in a controlled manner.