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Module four: Specialist Electrician's Tools

Voltage Detector


Voltage detectors are tools used for safe and reliable indication of live wires, an important tool for safety when working.

Non-contact voltage detectors are intended to be used without having to touch any live wires, instead they begin to flash, beep, or both when it detects a power source nearby.

Voltage detectors do not actually measure or detect any voltage!

They instead pick up on electric fields. Electric fields are generated by voltage; the greater the voltage, the greater the electric field.

We then have magnetic waves, which are generated by the current, which have the same relationship as the voltage and electric field.

Electromagnetic waves come from sources which have a voltage, and this is what the non-contact voltage detector picks up on.


How is it used?

Always work safely, begin by testing against the known live source in the working area, this could be a light switch, socket, or other electrical source. 

Hold the voltage detector like a pen, behind the safety guard, and gently hold over the suspect area.

If the pen lights up the circuitry is live and not safe to work on, always remove the power before beginning to work on live circuits.

If the pen does not light up, the circuitry is not live and safe to work on.

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