 # Electrical Testing Glossary of Terms

AC Voltage: Alternating Current Voltage is when an electric current where the flow of the electric charge is periodically reversing direction.

Amps: An amp or an Ampere is a unit of electric current equal to a flow of one coulumb per second.

Bandwidth: Bandwidth is a range of frequencies within a given band, which are used for transmitting a signal.

Capacitance: Capacitance is the ability of a system to store an electric charge.

Capacitive Coupling: Capacitive Coupling is the transfer of energy within an electrical network using displacement currents which are induced by existing electric fields between circuit nodes.

Centre Tap: A centre tap is a contact made to a point at halfway along a winding of an inductor or a transformer, or along the element of a resistor or a potentiometer.

Common Mode Rejection Ratio (CMRR): Common mode rejection ratio measures the ability of the device to reject common mode signals.

Current: Current is the flow of electricity which results when there is an ordered directional movement of electrically charged particles.

DC Voltage: Direct Current Voltage is where the electric current flows in a constant direction.

Earth Loop: An earth loop is an unwanted electric current path within a circuit which results in stray signals or interference.

High Tension: High Tension is an alternative term for high voltage.

High Voltage: High voltage is an electrical potential which is large enough to cause damage or injury.

Insulation Resistance: Insulation resistance is the alternating-current resistance between two electrical conductors or two systems of conductors which are separated by an insulating material.

Lamp Test: Lamp test is a piece of equipment which is used to determine whether there is an absence or presence of an electric voltage in a piece of equipment under test.

LCR Meter: An LCR meter is a type of electronic test equipment which is used to measure the inductance (L) capacitance (C) and resistance (R) of an electronic component.

Loop Testing: Loop testing is a method of evaluating an electrical circuit with its abilities to engage in protective devices.

Multimeter: A multimeter is an instrument which has been designed to measure electric current, voltage and usually resistance over several ranges of value.

Normal Mode Rejection Ratio (NMRR): Common mode rejection ratio measures the ability of the device to reject common mode signals.

Neutral: Neutral is the wires of a circuit which carry current “back” from an appliance or light.

Oscilloscope: An oscilloscope is a device for viewing oscillations by a display on the screen of a cathode ray tube.

Ohm: A unit of electrical resistance, it transmits a current of one ampere when it is subjected to a potential difference of one volt.

Proving Unit: Proving units are lightweight and portable calibration tools which are designed to use with two-pole voltage testers. They will evaluate the internal components of the voltage tester and see whether they are working correctly and that measurement accuracy is maintained.

RCD: RCD is a residual current device and is a life-saving device which has been designed to prevent you from getting a fatal electric shock if you were to touch something live.

Resistance: Resistance is a measurement of difficulty which is encountered by a power source when forcing electric current through an electric circuit. It is measured in ohms.

Volts: A unit of electromotive force, it is the difference of potential that would carry one ampere of current against one ohm resistance.