Indicators, testers

Indicator, phase meter, tester and sampler in action. Types of indicators and their applications

An electrical indicator, also called a unipolar voltage tester, is a simple measuring instrument for checking the presence of alternating voltage in the range of 100 to 1000 V at frequencies of 50 to 500 Hz. Although a simple device, there are several basic types of indicators with different device and construction. They are also called phase testers, electrical phase meters, voltage testers or voltage indicators, voltage probes. The electrical indicator is a portable device that is designed to detect the absence or presence of voltage in the network or on the current-carrying elements of electrical installations. This check is carried out before connecting the portable earthing or switching on the earthing knives, as well as before starting work on electrical installations. In these cases, it is not necessary to determine the value of the voltage, it is only necessary to know its presence or absence.
The safety of an electrician depends on the voltage indicator. Only after making sure that there is no voltage on the elements that will be processed can you start working on repairing a lamp, switch or socket.

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Types of indicators

What types of indicators are there and how do they differ?
According to the measured voltage:

• Up to 1 kV
• Above 1 kV

Measuring testers up to 1 kV are divided according to the number of poles:

• Unipolar indicators
• Bipolar indicators

Universal indicators are divided according to the type of measured current:

• For alternating current
• For direct current

According to the type of indicator:

• Glim lamp indicator
• Phase meter with LED indicator
• Digital indicator
• Non-contact indicator

Glim Lamp Indicator Simple indicators contain a series-connected test lead, a small glow lamp, a ballast resistor from 820 kΩ to 1 MΩ, and a contact surface. Mechanically, the electrical indicator is often constructed in the shape of a screwdriver. The tip of the standard indicator (screwdriver blade) represents the measuring tip and is used to measure by placing it on the wire under test or inserting it into the socket in the socket. The other end of the indicator should be lightly touched with a finger, then the electric circuit is closed by the human body. If the wire is live, the lamp will light up. The current passing through the finger is usually on the order of microamperes and is safe for humans. When the tip of an indicator touches the neutral or ground wire, the lamp does not light because they are at the same potential as the environment.
In principle, a standard indicator cannot be completely relied on, since the current flowing is dependent on the transient resistance between the contact and the skin of the finger. If the glow lamp illuminates upon contact with a neutral or ground wire, a failure of the electrical indicator may be assumed. Measurement with an indicator is indicative and cannot be considered as proof of quality grounding. To assess grounding, it is necessary to measure the loop resistance. This is the so-called resistance of the disconnection loop, a mandatory part of the measurement during the revision of electrical installations.

Indicators versus bipolar voltage testers

Electrical indicators are not suitable for categorical and reliable voltage measurement. Bipolar voltage testers are suitable for reliable voltage measurement. These devices are also safer because no current passes through the human body during the measurement. A damaged indicator, for example with a faulty ballast resistor, can cause electric shock. Commonly available multimeters or installation testers can also measure voltage, but this is no longer just a voltage tester in the original sense of the word. As a minimum check of the functionality of each indicator, it is recommended that you check its functionality before each use. At the very least, it will show a faulty indication.
The use of an indicator to check contacts with the so-called child protection is not applicable. A common design for this protection is a plastic strip hinged to the inside of the outlet cover. To rotate the fuse and release access to the contacts, insert the pins into both contacts at the same time. This is to prevent an unwanted object (such as a nail, screwdriver) from being inserted into one of the outlet holes and causing an electric shock. The principle of this protection prevents the use of indicators. Bipolar testers can be used for such measurements. They often have a holder that holds the two tips at an axial distance of 19 mm, i.e. at a distance between the contacts of ordinary European contacts.

Non-contact tester

Non-contact indicators detect an electric field in the immediate vicinity of the wire via a sensor and signal it optically, for example with an LED diode. Battery required for operation. With sufficient sensitivity, it is possible to detect voltage even in an insulated wire. Non-contact indicators are suitable for checking AC voltages, they are not applicable for DC voltages. There is no separate standard for voltage indicators, they must comply with the general standard for measuring devices БДС EN 61010-1 and 2. Some non-contact phase meters have both light and sound signaling

Varieties of indicators

They differ in construction, source of light indication signal. Often, specialist electricians are interested in the following types:

• Professional testers
• Quality testers
• Digital testers
• Contactless testers
• Sound testers
• LED testers
• Inductive tester

Indicators or single-pole voltage testers for checking the presence of alternating voltage in the range of 100 to 1000 V at frequencies of 50 to 500 Hz can be found in our online tool store.

Some basic rules for working with an indicator

The use of an incandescent lamp instead of a phasor as a homemade voltage indicator is prohibited. This lamp is dangerous and unreliable.
To find the phase of current-carrying elements or wires using a unipolar indicator, you need to take your indicator in your right hand, holding the dielectric handle, touch the blade to the tested wire or current-carrying element. In this case, the left hand must be placed behind the back so that it does not accidentally touch live elements or grounding. With the finger of your right hand, touch the metal contact of the unipolar pointer. It is more convenient to touch with a thumb.
If the glow lamp is lit, it means that the current-carrying element you are checking is under phase voltage. If the lamp does not light, then there is zero or no voltage at all.
In the case of a bipolar indicator or voltage tester, the body pin where the indicator is located touches one contact of the element under test. The second pin touches the other contact - phase or zero. The absence or presence of voltage is determined by the intensity of the lamp. Using such a device is not difficult at all.

When checking the voltage, it is necessary to work carefully and accurately, observing the safety rules, because it is very dangerous to human life.
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Technical specifications of products from the Indicators, testers category are subject to change without notice. The images of the products in a category are provided by manufacturers and distributors, but sometimes they can only be informative. Current price means the manufacturer's or supplier's suggested retail price.

Indicator, phase meter, tester and sampler in action. Types of indicators and their applications
Types of indicators
Glim lamp indicator
Indicators versus bipolar voltage testers
Non-contact tester
Varieties of indicators
Some basic rules for working with an indicator