Which component helps ensure safety during electrical maintenance?

An isolator switch plays a crucial role in ensuring safety during electrical maintenance by providing a means to completely disconnect electrical circuits from their power source. This is vital when maintenance personnel need to work on equipment or conduct repairs without the risk of electrical shock or accidental re-energization.

The isolator switch is designed to be used when it is necessary to ensure that no current flows through a circuit, making it safe for technicians to access and work on electrical components. Unlike devices such as circuit breakers or fuses, which are typically protective devices meant for fault conditions, an isolator switch is specifically utilized to provide a safe working environment by ensuring that maintenance work can be conducted without the risk of live electrical parts.

In the context of the other options, while circuit breakers and fuses are important for protecting circuits from overloads and faults, they do not eliminate the danger of live voltage during maintenance work. An electric meter, although useful for measuring voltage, current, and resistance, does not directly contribute to safe maintenance procedures by isolating the circuit.