woRKinG oF ElectRicaL TeSTer

How Electrical Testers are Working

Inside an electrical tester

Components:

Metallic rod, Resistor, Neon bulb ,Spring connector,Metal Head ,Plastic Sheath (Provide Insulation )

Connection:

                       Metallic rod with one end looks like screw driver , Other end contact with Resistor.Resister in the range of 2.2 M_Ohm - 10 M_Ohm to limit the current in order to sub-milliampere level maximum   that enters neon bulb One end of Neon bulb contact with High watt resistor and the other end connected with Spring. Spring connected with metal head which provides contact to earth by  means of our body. Plastic Sheath that covers the entire testers provide overall insulation between our body and live voltage.

Operation:

• When the tip of tester touches the live wire there is some flow of current that glows the neon bulb, if our body touches the metallic head. Because our body provides the closed path to the circuit  via earth.If we don't touch metallic  head the lamp will not glows because the circuit remains open. We can use testers from 90V to a high range. Neon bulb glows even for a small current.Glowing brightness of neon lamp depends on voltage level. High watt resistor acts as a heavy load even for a high voltage.Lamp may not glow if we have heavy insulation from ground.If resistor fails heavy current flows through our body leads to death.