A electric test lead is a device that connects electronic testing equipment to an electrical device being tested through a meter. Test leads are constructed of wire that is coated in red or black material with probes on the ends, allowing an electrician to test a circuit.
Most often, test leads are constructed of very fine wire that is stranded. This allows the wire to be very flexible and able to conduct electric current. The coating on the wire keeps the wiring from touching skin. A person using test leads must be aware of which probe is positive and which probe is negative, as both probes are used to measure voltage, current and two-terminal devices.
There are many different types of test leads including tweezer probes, pogo pins, passive probes and oscilloscope probes. Each is used for differing purposes. For instance, tweezer probes are used by fixing the probes to a tweezer-like mechanism. This type of probe is ideal for closely spaced pins when measuring voltage or circuit parameters. Passive probes are used to minimize loading. A pogo pin or spring load is used for component leads and device testing. Typically, this type of probe presses into probe sockets found in automatic testing equipment.