The Megger 6220 series four-piece duplex test lead set includes two current leads with spring clamps and two potential leads with crocodile clips for use with the with Megger DLRO200 and DLRO600 digital microhmmeters. These current and potential test leads are for taking four-wire resistance measurements, which are more accurate than two-wire resistance measurements and allow low resistance values to be detected. The spring clamps have a 2.4" (60 mm) jaw opening, and the crocodile clips (also known as alligator clips) have a 0.9" (22 mm) jaw opening. Both the spring clamps and crocodile clips provide hands-free connection to a conductor. The leads have a maximum current input of 600 amp.
A test probe, test lead, test prod, or scope probe transmits an electrical signal to a testing device for display and analysis. Designs range from simple test leads with probe-style or clamp-on tips to more complex oscilloscope probes and current detectors. Some test probes, such as basic test leads, have wires with tips for connecting to test equipment. Other test probes, such as voltage detectors, are built into the meter. Depending on what is to be tested, the probe might either be passive or have active parts that require external power to operate. Some probes require contact for testing, while some are capable of taking measurements from a distance. Some also have finger barriers, insulation, or other features to help protect the operator's hand from electrical shock and burns. Test probes are rated according to the amount of voltage, current, temperature, or other input they can measure. When choosing a test probe, the maximum amount of input that the probe can measure should match or exceed both the maximum amount that can be tested by the test equipment, as well as that of the property expected to be present in the application.
Megger manufactures equipment for cable fault locating, protective relay testing, telecommunications and data integrity, and power quality testing under multiple brand names, among them Megger, Biddle, States, and AVO. The company, founded in 1889, is headquartered in Dover, England, and meets International Organization for Standardization (ISO) 9001:2008 standards.