Electrical Screwdriver With Neon Bulb Tester

Screw Driver, Electrical, With Neon Bulbs

Integrated Safety Circuit: Features a built-in, high-value resistor that limits the current flowing through the user to a safe, imperceptible level, ensuring total safety during testing.

Transparent High-Impact Handle: Constructed from shatterproof, crystal-clear cellulose acetate or polycarbonate, providing $360^{\circ}$ visibility of the neon bulb from any angle.

$1.41

Quick Answer: A neon tester screwdriver is a small flat-blade screwdriver with a neon bulb and a high-value resistor inside its transparent handle. When the tip touches a live AC mains conductor and the user touches the metal cap, a tiny current flows and the neon glows, showing that voltage is present.

How the Neon Lights

Inside the handle the blade, a resistor, the neon lamp and a spring connect in a line to the metal cap at the end. A neon lamp needs a certain minimum voltage before the gas inside ionises and glows. With the tip on a live mains conductor and a finger on the cap, the user’s body acts as one plate of a capacitor to earth, and a very small alternating current passes through the lamp and resistor. The resistor exists to keep that current very small.

This makes the tool handy for a quick check of which terminal at a socket or switch is live, and for showing students that a neon discharge needs a threshold voltage. It also explains its limits. The lamp does not light on low-voltage circuits such as school cells, battery packs and low-voltage power supplies, and it can fail to light on a live conductor in bright light, with a poor contact, or if the user is well insulated from earth. The working voltage range of this model is not in its title and can be confirmed.

A neon tester is therefore an indicator, not proof that a circuit is dead. Before work on mains wiring, trained users isolate the supply and confirm it is dead with a proper two-pole voltage tester that has been checked on a known live source. The blade is small and suited to terminal screws; for general slotted screws, see the flat type screwdriver.

Care & Handling

Check the tester on a known live source before and after use; a lamp that fails to light could give a false result.
Do not use it if the handle is cracked, the cap is loose or the blade is bent.
Hold it only by the handle and cap, with fingers off the blade.
Use only light turning force; the blade is thin and not meant for large screws or prying.

Specifications

Type	Flat-blade screwdriver with neon voltage indicator
Indicator	Neon lamp and series resistor in a transparent handle
Detects	Presence of AC mains voltage on a conductor
Does not detect	Low-voltage DC from cells, batteries and low-voltage supplies
Working voltage range	Confirm at enquiry

Applications

Identifying the live terminal at sockets, switches and fittings during supervised electrical training
Physics demonstrations of neon discharge and striking voltage
Tightening small terminal screws on switched-off fittings and plugs
Quick preliminary checks by maintenance staff before full testing

Why Choose LabEquip

Electrical wiring courses, physics departments and site maintenance teams use a neon tester screwdriver for quick checks, always alongside a proper voltage tester. LabEquip lists it with its general lab products, and it pairs with the electrical and electronics apparatus range; ask about voltage range on the contact page.

Frequently Asked Questions

Why must I touch the metal cap for the neon to light?

Your body completes the path to earth through its capacitance. Without that contact, too little current flows through the lamp and resistor for the neon to strike and glow.

Will it work on a 9 V battery or a school power supply?

No. A neon lamp needs a much higher voltage than cells, batteries and low-voltage supplies provide before it glows, so the tester shows nothing on those circuits.

Can I rely on it to show that a wire is dead?

No. It can fail to light because of bright light, poor contact, insulating footwear or a faulty lamp. Isolate the supply and prove it dead with a two-pole voltage tester that has been checked on a known live source.

Is the neon tester safe to use?

When the handle, resistor and cap are intact, the resistor limits the current through the user to a very small value. A damaged tester must not be used, and work near live parts should only be done by trained people following safe practice.

Why does the neon sometimes glow faintly on a switched-off wire?

A disconnected cable running next to live wires can pick up a voltage by capacitive coupling, which is enough to make the neon glow faintly. This is another reason the tester is only an indicator.

Can the blade be used as a normal screwdriver?

For small terminal screws on switched-off fittings, yes. Avoid large screws, heavy torque and prying, which can bend the blade or crack the handle and damage the tester inside.

Last Updated: September 2026