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How to use a voltage detector

Shop for Voltage Testers

push button to turn on non-contact voltage detector

Step 1- Turn on device

Turn on the voltage detector according to the instructions provided.

check the battery on non-contact voltage detector

Step 2 – Battery check

If the voltage detector has the facility, always begin by checking the battery, as the instructions state.

If the detector does not have a battery checker (and even if it does) watch out for dim or non-functioning LED ‘ON’ lights as this is also a sign of a low battery.

After these checks, change the batteries if necessary.

test detection with non contact voltage detector on plug socket

Step 3 –¬†Perform test detection

This step is important and must be carried out every time any voltage detector is used.

To ensure the voltage checker is working, place it on or near a known hot (live) electrical source to see if it indicates power as it should. If it does not (and you have changed the batteries) then do not use the detector. Instead, you probably need to replace it.

adjusting sensitivity on a non-contact voltage detector

Step 4 –¬†Set sensitivity

This step can be carried out alongside the previous step.

If present, adjust the sensitivity scale to the maximum (that’s most sensitive – the lowest voltage detection). If the detector immediately starts to indicate that a voltage has been detected, lower the sensitivity until it stops. Then, move towards a known voltage source, lowering the sensitivity as you go, until it only goes off at the distance you want. This will be dependent on what you are testing .

Beware of the ghosts... Or at least remember there may be ghost voltages detected.
detecting with non-contact voltage detector

Step 5 – Detect

Place the voltage detector near the source you are checking. The detection is carried out slightly differently for certain applications…

non-contact voltage detector in use on plug socket

For plug sockets:

In a standard UK plug socket, the top terminal is ground, the left is neutral and the right is hot (live). This means that if there is a power supply to the socket, the voltage detector should start indicating near or inside the right terminal.

voltage detector checking for broken circuit

For breaks in a wire:

To check for breaks in a circuit, plug in the item being tested and switch on the power.

Begin at the power source with your voltage detector and follow the wire along. The detector should be indicating from the start and continue all along the wire.

voltage detector on cable If the indicator stops indicating at a certain point, move the detector all the way around the wire to double check (even the cables have a live and a neutral side). If the detector still does not find anything, then there is a break in the circuit.
multiple electrical wires for non-contact voltage detectors

For multiple wires in a box:

If you are working on a project which requires opening up and checking electrical equipment, ensure the sensitivity is set low, so that the signal from different wires can be distinguished.