What safety tool can indicate voltage without direct contact?

The correct answer is a voltage detector, which is a safety tool specifically designed to indicate the presence of voltage without requiring direct contact with live wires or components. Voltage detectors operate on the principle of detecting the electromagnetic field generated by electrical currents flowing through conductors. They can be used to quickly verify if a circuit is energized, helping prevent accidental electric shocks and ensuring that work can be performed safely.

Using a voltage detector has advantages in terms of safety, as it allows technicians to assess the presence of voltage from a safe distance. The tool provides instant feedback through visual or audible signals, making it easy to determine if the area is safe for further work.

The other choices do not fulfill this function. A wire brush is primarily used for cleaning and does not serve as a voltage measurement tool. An insulation tester evaluates the resistance of insulation but requires connection to the electrical circuit and does not have the capability to indicate voltage without direct contact. NTVD is an acronym that does not correspond to a commonly recognized safety tool for indicating voltage in the context of electrical work.