What is an electric tester? what is the use of electrical tester

What is an electric tester

An electrical tester is a device that is used to detect the presence of electricity in equipment. Electrical devices consist of many parts and these parts mostly conduct electricity and there are other parts which block the electricity they are insulators if the insulator between parts that are accessible by humans and parts that are hazardous is defective, the person who uses the device could get electrical shock and it could be fatal too. So to avoid all these problems electrical testing is done by using some electrical testers. In order to prevent such accidents, the safety of the electrical equipment must be evaluated. The important tests that must be conducted are voltage withstand test, insulation resistance test, leakage current test, and earth continuity test.

Why measuring and testing and what is the use of electrical tester

When a piece of electrical equipment is installed then from that time the deterioration of electrical equipment would begin, if the deterioration is not checked it can cause electrical failures and malfunctions. The purpose of electrical testing is to check the failures and malfunctions and to detect hazardous that can cause the failure of equipment or interruption of electrical service. Testing of electrical equipment should consist of conducting routine tests, inspections, repairs of electrical power system apparatus such as generators, transformers, circuit breaker, cables load motors, switchgear assemblies along with associated equipment comprised of control wiring, protective device and relays, supervisory equipment and indicating and metering instruments.

By doing electrical tests we can accurately measure these following values

  • Insulating values of insulation
  • Resistive and capacitive loss
  • Power factor
  • Relationship of primary and secondary voltages
  • Trip level and accuracy of relays and low, medium and high voltage circuit breakers

What are the types of electrical testers

Digital multi-meters

This device uses solid-state microprocessors to make electrical measurements, digital multi-meters are accurate than analog multi-meter and they are compact than analog meters. Digital multimeters are able to capture near-instantaneous information, record trends or download information to a computer. Mostly the display of digital multi-meter would be LCD or LED. Digital multimeters can be used to measure AC voltage DC voltage, resistance, capacitance, continuity check, etc. Some digital multi-meters has the ability to connect to a computer. In certain tests, we may need to transfer data from memory of the multi-meter to a computer. Auto-ranging and auto polarity is another important feature of the digital multi-meter auto-ranging that will help to select the range automatically that will yield the best resolution of the measurement. Auto polarity feature will protect the digital multimeter when the polarity is reversed, it will show polarity with a negative sign. In case of overload or over-range, OL reading will appear on the display



An ohmmeter is an instrument which is used to measure electrical resistance. In the ohmmeter, the energy required for its operation is received from the circuit under test. In this device, the energy is supplied by a self-containing source of voltage, such as a battery. There are ohmmeters which can be used to measure low values of resistance and high values of resistance. A continuity tester is the one that measures the low values of resistance while insulation resistance tester is used to check the high values of resistance. An ohmmeter can be used to determine the resistance of a circuit component such as heater elements or machine field coils, measuring and sorting of resistors used in electronic circuits


Voltage testers

Voltage testers are used to measure or check the presence of voltage in an electric circuit. There is a non-contact voltage tester and they have many features as they can quickly check the presence of AC voltage. These devices can check the voltage across the electrical wiring, outlets, etc. We can do the testing by placing the top of the tester in the outlet slot or it can also be done by touching the outside of the wire. Non-contact testers are able to detect the voltages from 70V to 440V AC. This device has both visible and audible indicators. Loud audible chirping will be emitted by the detector and its pitch would change according to the proximity of the probe to the AC voltage source. Bright flashing LED’s also indicates the presence of AC voltage.


AC high voltage insulation tester

By using high voltage insulation tester we can detect breakdowns, grounds, and shorts. This device can be used to do the high voltage test at different steps while manufacturing or repairing of an electrical device. By using this device we would be able to detect the insulation failure at the early stage. These devices are built with a breakdown light and their purpose is to indicate any problems. Safety switches are present in this device so in case of any breakdown the current flow will be stopped quickly.


Receptacle tester (plug tester)

These testers are used to detect wiring errors and this device is also known as outlet tester, these devices are plugged into the outlet to check the wiring errors. If there is an error then this device will show it with the help of lights in it. Receptacle tester will detect errors such as missing electrical ground or neutral etc.



Growlers are devices that are used to test the shorts, opens, or grounds in armatures or stators of electric motors or generators. When used the growler is so planned on the armature that the iron of armature or stator under test completes the magnetic circuit. When an AC is passed through the growler winding an alternating flux is created in the growler winding an alternating flux is established in the iron of the growler and of the portion of the armature or the stator, iron spanned by the jaws of the growler. If there is a short in the armature then circulating currents will be induced. These circulating current produce their own magnetic field that will create the growling sound. Some growlers have meters and test prods and by such a growler we can detect the short by noting the current drawn by the growler, by measuring the voltage across the coil open can be detected.