What Is a Voltage and Continuity Tester? Types and Selection Criteria
A voltage and continuity tester is a handheld instrument that shows by light, display and sound whether a conductor is live and whether a circuit is unbroken.
A voltage and continuity tester is a handheld test instrument that uses light, a display and sound to show whether voltage is present on a conductor and whether a circuit is unbroken. It is used to verify that a line is de-energized before starting work, to find faults at fuses, switches and connection points, and to locate a break in a conductor.
Types
| Type | How it works | Used for | Catalog example |
|---|---|---|---|
| Two-pole voltage tester | Two probes touch the circuit; the voltage step is shown by LED or LCD, continuity is tested with the battery | Verifying absence of voltage, fault finding, phase sequence | UT18C, UT18D, UT18E |
| Non-contact AC voltage detector | The pen tip is held near a conductor or socket; it beeps and lights up when it senses an AC field | Quick pre-check, finding the live wire in a wall or cable | UT12D, UT12E, UT12M |
A non-contact detector only indicates the presence of AC voltage; it does not replace a two-pole tester for verifying the absence of voltage.
Selection criteria
- Voltage range and AC/DC: Two-pole models show voltage in steps such as 12 V, 230 V, 400 V and 690 V. For batteries, solar panels or DC control circuits choose a model that tests AC/DC; a non-contact detector does not sense DC voltage.
- Measurement category (CAT): Under the IEC 61010 series, CAT II covers socket circuits, CAT III distribution boards and fixed installation, and CAT IV the origin of the supply (meter, before the main fuse). Use the tester only up to the category and voltage on its label.
- Additional tests: Continuity, polarity and phase sequence. On the catalog models the phase sequence test covers 100–400 V AC (50–60 Hz) or 57–400 V AC (50–400 Hz).
- Power: Most models run on 2 × 1.5 V AAA (R03) batteries; one catalog model is powered by the circuit under test and needs no battery. With flat batteries, continuity testing and non-contact detection do not work.
Common mistakes
- Confirming absence of voltage with a non-contact detector: Shielded cable, DC or a deeply buried conductor may not be detected; verify with a two-pole tester.
- Using the tester without proving it: Test it on a known voltage source before and after the measurement.
- Use outside its category: Measuring at a main distribution board with a CAT II tester.
- Testing continuity on a live circuit: Continuity is tested only on a de-energized circuit.
Related standard
- IEC 61243-3: Live working, voltage detectors, part 3: two-pole low-voltage type. The product names carry no declaration of conformity with this standard; if a specification requires it, ask the manufacturer for the document.
Models in the catalog
The Voltage and Continuity Testers category lists 9 active models from Unit:
- Two-pole voltage testers: UT18C, UT18D and UT18E (compare AC/DC measurement and additional tests on the product pages)
- Non-contact AC voltage detectors: UT12D, UT12E, UT12M
- Other: UT15B with waterproof housing, UT15C tester, UT22B-EU voltage test pen
UT15C, UT12D and UT22B-EU are sold on a quote basis; the other six models can be added to the cart. To measure the value of voltage, current and resistance see Multimeters and Clamp Meters, for three-phase lines Phase Sequence Testers, and for other instruments Electrical and Electronic Testers.
Frequently asked questions
What is the difference between a non-contact voltage detector and a two-pole tester?
A non-contact detector senses the AC field without touching the conductor and is meant as a pre-check. A two-pole tester shows the voltage between two points directly; absence of voltage before work is verified with it.
What is the difference between a voltage tester and a multimeter?
A tester shows whether voltage is present and its approximate value without selecting a range, so there is no risk of a wrong setting. A multimeter measures voltage, current and resistance as numbers, but the right function and range must be selected.
What is a phase sequence test for?
It shows the L1-L2-L3 order on a three-phase supply. If the order is reversed, a motor runs in the wrong direction; it is checked before connecting.