Last updated: August 17, 2021

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A very useful tool if you are going to deal at some point with electricity. After all, it's always important to know if there's electric current in something you're going to mess with.

Used for work in various branches, and in different ways, a voltage detector is an extremely useful tool. Used by electricians and also amateurs, you'll like to have one nearby when you're changing the sockets in the house, or installing the new shower.


  • A voltage detector serves to indicate whether an object or wiring is live.
  • Today, the measurement can be performed without the need to directly approach the item (contact).
  • Being a tool for use in the electrical part, care and precautions are important to reduce any chance of an accident.

The Best Voltage Detector: Our Picks

Choosing a voltage detector is not always simple. There are a variety of models with different uses, many aimed at the professional electrical market. To help you with the possibilities, we present here some of the best available.

Buying and rating guide for a voltage detector

Despite the specific purpose, there are different models of voltage detectors on the market. Information such as category, frequency and current, are common in the description and this can confuse you. To avoid a bad choice, just follow our guide on the subject.

Homem usando um detector de tensão em um painel elétrico.

Some models of voltage detectors also have a LED screen to identify the amount of voltage present. (Source: Katarzyna BiaÅ'asiewicz / 123rf)

What is the function of the voltage detector?

Being a tool of simple use, its use is also basic, although very important. A voltage detector serves to inform the user whether an object has an electric charge.

This occurs by means of a luminous or audible (or even both) warning, where the detector automatically triggers in the presence of voltage. Some more advanced versions can even indicate the voltage level, thanks to the display on these models.

The most basic models, on the other hand, only have an audible alert. This is also sufficient when the aim is to know whether there is energy in the object or not.

Mão usando um detector de tensão modelo caneta.

A voltage detector serves to inform the user whether an object has an electrical charge. (Source: Pisit Khambubpha / 123rf)

To check if any electrical component still contains charge, or if a wire is energised; the equipment has many uses. In a passage box, you can use the detector to know which lines are "live", helping you do your job.

It's a quick diagnostic tool.

Also used as a quick diagnostic tool, it can determine power problems in a particular location. With point-by-point analysis, you will realize how far the line is energized and the consequent location for adjustment.

In situations where high voltage has to be measured, the use of special equipment is recommended. They usually provide the nominal voltage present in the line tested, ensuring the necessary amplitude so that a measurement fault or even an accident does not occur.

What are the advantages of a voltage detector?

They are very small devices, therefore very portable. Simple and easy to handle, they offer greater safety for certain electrical services.

Very affordable price and robust material, the voltage detector has an excellent cost-benefit ratio.

Do you want to know if it's worth having one at home for routine maintenance?

  • Most of them are portable
  • They serve as an early warning
  • They are robust and lightweight tools
  • Highly durable
  • They may emit electromagnetic radiation
  • Misuse can lead to false results

What are the types of voltage detectors?

Voltage detectors work in different categories, and also with two main models.


Voltage meters and voltage detectors are included in four possible categories. Their function is to indicate what is the maximum load capacity they can absorb, without risk to the user. They are:

  • Category I: The lower exposure protection range, designed for use in smaller circuits such as domestic appliances. Transient between 2.5 and 4,000 V peak.
  • Category II: Used for measurements on wiring and sockets of equipment with low and medium power consumption. Transient between 4 and 6.000 V peak.
  • Category III: Has a wider range of use, being applied in both residential and commercial environments. Transient between 6 and 8.000 V peak.
  • CategoryIV: The highest range, can even be used in distribution panels. Transient between 8 and 12.000 V peak.


There are on the market, two main types of detectors, according to their method of operation. Serving to measure the electrical charge of an object, they can be contact and non-contact detectors.

Non-contact: Usually pen-shaped, they have a non-conductive tip made of plastic or similar material. Its operation verifies the presence of magnetic field on the wire, and activates the detection signal if encountered.

With contact: They allow to detect the presence of AC voltage by making physical contact with the live point. They can work with fixed or movable probes (items that will need to be placed on the object to detect voltage).

Without contact With contact
Portability Portable Both: Fixed or movable
Other items They do not need attachments They may need probes
Use Use in places of difficult access Use in places of difficult access
Category Most common use in situations of lower category Use in any category

Purchase Criteria: How to choose your voltage detector

We often end up having to carry out some work involving electricity. Of course, having a voltage detector on hand will help a lot. However, they are different from each other, and you need to know exactly what you need.

In this section we will go through the most important criteria to take into consideration when buying a voltage detector:

  • Quality of construction
  • Indicator system
  • Energizing mode
  • Category

Check out the criteria in detail now to make the best choice.

Quality of construction

Electricity is capable of causing serious damage, so you need to be aware of the capabilities of your voltage detector. Although all versions are robust, there are some particularities among them.

Although the manufacture of a voltage detector is surrounded by care, there are versions with more appeal in safety. Rubberised models, resistant to dust and splashes, among other possibilities.

Keep in mind how you intend to use the tool, to seek a suitable construction quality. Because every extra resource means a bigger investment.

Imagem de uma pessoa segurando um detector fora de uso, com um pequeno quadro de energia desfocado ao fundo.

The visual and acoustic signals ensure greater safety when using the voltage detector. (Source: pixeldieb / Pixabay)

Indicator system

Most voltage detectors usually come with at least an audible signal as a detection alert. However, nearby situations may not allow you to be able to hear this emission.

If you are near a construction site, it is possible that you may understand a false negative yourself. The consequences can be disastrous.

Opting for a model with double indication - light and sound signal - will double your chances of perceiving the indication of the voltage detector. Something that will certainly make your life much easier when you need to operate the tool.

In the same way, it is possible that one of the systems is faulty. By opting for dual indication models, you will have less risk of being exposed to a "live wire" or electrified object.

Mode of energisation

As a rule, most of the voltage detectors you find on the market use batteries for operation. However, the options within this condition remain huge, from AA batteries to

Some even require electrical power for operation (special cases, of higher voltage detection).

Please check before purchasing which form of energy the voltage detector works with. After all, it is not always easy to find certain batteries for replacement on the market


It is always important to remember how dangerous electrical energy can be. And electrical equipment can work with different voltages and voltages.

For this reason, it is important that you have a tool that is compatible with the object you intend to identify the voltage, or even the wiring. And this is where the product category comes in.

When it comes to electricity, tools for measurement and detection have a category. It has already been presented in a previous section, and serves to identify up to what level of voltage the equipment is capable of withstanding.

Of course, you should never underestimate the voltage detector's own manual. This is where you will really find the data you need for your decision making, and for the best operation of the tool.

(Source of the highlighted image: Bru-nO / Pixabay)