What safety measure should be taken when working on electrical systems?

Disconnecting power sources before making any repairs is a crucial safety measure when working on electrical systems. This action significantly reduces the risk of electric shock or other injuries that can occur from accidental contact with live electrical components.

When power is disconnected, it ensures that there is no electrical current flowing through the system, allowing technicians to work safely and focus on the repairs without the constant hazard of electricity. It's important to verify that the power is indeed turned off, often by using a multimeter or a voltage tester. This practice is fundamental to ensuring personal safety and should be a routine part of the process whenever maintenance or repairs are performed on electrical systems.

The other options present scenarios that either increase risk or are not standard safety practices in electrical work. Working in wet conditions, for example, can actually enhance the risk of electric shock, while wearing loose clothing does not provide adequate protection and may even pose a risk of entanglement in machinery. Additionally, using non-insulated tools is hazardous since these tools can conduct electricity, leading to serious harm.