A retired electrician revealed to me the hidden secrets of the voltage tester screwdriver.
A voltage tester isn’t just a basic tool; when used properly, it can become an indispensable instrument for detecting faults, preventing accidents, and making any household electrical work easier. Here’s how to get the most out of this device, based on the experience of a former electrician.
Why the tester lights up on both sides of an outlet
It’s common for the tester to light up on both contacts of a socket when testing both contacts, causing confusion. Some possible causes:
- Residual voltage : When there is an open or poorly connected circuit, a small ghost voltage may circulate.
- Polarity reversal : Poorly made connections can make it look like both poles are live.
- Electromagnetic induction : In locations with high-load cables, eddy currents sufficient to ignite the tester may be generated.
Recommendation : Don’t ignore it; you may be facing an installation error that requires attention.
How to Identify Live and Neutral Wires with a Voltage Detector
To use the tester correctly in a socket:
- If the tester lights up when you touch a point, it is a live wire .
- If it doesn’t light up, you’re touching neutral .
Tip : Correctly identifying conductors is key to avoiding shocks, especially during installations or repairs.
Alternative use: check continuity of a circuit
Although it is not its primary function, the tester can indicate continuity:
- Touch one end of the circuit with the tester and the other to ground.
- If it lights up even slightly, there is continuity.
Useful for detecting cuts without disassembling cables or entire installations.
How to detect a power leak in an appliance
- Place the tester on the metal chassis of the equipment.
- If it lights up, there is current flowing into the casing: risk of shock .
Recommended action : Disconnect and consult a technician.
Checking a fuse without removing it
- Touch both ends of the fuse.
- If the tester lights up on only one side, it is burned out.
Practical for diagnosing without cutting power or disassembling.
Check keys and outlets
- Place the tester on the terminals or slots.
- If there is no signal, it may be defective.
Tip : Perform this check before replacing components unnecessarily.
With a few simple tricks, a voltage tester transforms from a simple detector into an indispensable technical aid. Understanding its operation and alternative uses can make the difference between a safe repair and an accident.
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