Voltage detector principle and method of use

Voltage detector principle

No-metal-contact voltage detectors usually detect voltage by means of electrostatic induction. When the voltage detector is placed in contact with the measurement target (for example, a power outlet), there is capacitance between the measurement target and the voltage detector. Similarly, there is capacitance between the voltage detector and its user, and between the user and the ground. If the measurement target is live, a minuscule AC current will flow via the voltage detector and its user. This minuscule AC current is detected using a high resistance inside the voltage detector and indicated to the user by conversion into light and sound. The current that flows is less than 1 μA and poses no danger to the user.

Procedure for using a voltage detector (how to use the Voltage Detector 3120)

1. Turn on the instrument.
Turn the switch clockwise. If the green LED fails to light up or if it lights up only weakly, replace the batteries.

2. Checking operation prior to use
Using an outlet or other power source that you know has a voltage, verify that the instrument is operating properly.

•    If the red LED lights up and the instrument beeps: The instrument is functioning properly.
•    If the LED gradually goes out and the instrument beeps faintly: Replace the batteries.
•    If the red LED does not light up and the instrument does not beep: The instrument may be malfunctioning.

3. Detecting voltage
Turn the instrument on, verify that the green LED lights up, and place the detector in contact with the object you wish to check.

•    If the red LED lights up and the instrument beeps: The wire is live.
•    If the green LED remains lit up: The wire is not live or is carrying a voltage of 70 V or less.

*The instrument’s maximum detector-to-ground voltage is 600 V AC. Do not use it to measure voltages in excess of that value.

How to use the Voltage Detector 3480/3481

Introducing safe, contactless voltage detection! This video introduces the compact Voltage Detector 3480/3481.