Cable megger test procedures

Updated February 21, 2017

Inevitable damage to electrical cables can cause them to not effectively transmit electricity or other signals. Even worse, these faults can cause electrical sparks which become a fire hazard. Cable meggers detect cable faults through the use of a pulse echo, which helps electricians and other technicians locate damage or disconuity to a cable. They can then find the damaged cable and repair it by cutting out the damaged wire, adding new wire and crimping it.

Locating Faults

Poor joints or impedence cause damages and discontinuities. Impendence is an opposition to alternating currents. Testers send a pulse down a cable at a velocity determined by the insulation of the cable, according to Biddle Megger. Changes in the cable will cause the pulse to be reflected back. Testers can find the location of the fault by tracking the amount of time that the pulse takes to reflect back to the cable megger.


The tester must adjust the velocity factor so he can get an accurate measurement of the pulse, according to Biddle Megger. He can set the cursor to the end of the cable and adjust the TDR until the right length is found.

Display Contrast

Sometimes, the distance units between meters and feet are configured by changing the propagation velocity units between a ratio and a distance per microsecond, according to Biddle Megger. The tester adjusts the display contrast to compensate for different viewing conditions.


The cable tester uses a backlight to compensate for different kinds of viewing conditions, especially in low light, according to Biddle Megger.


When testing the cable megger, the tester should replace the battery as soon as possible when the battery icon is flashing, according to Biddle Megger. Before replacing the battery, the megger should be powered off. If there is not enough battery juice in the megger, the polarity can damage Tes the device.

Binary Translation

The GOOSE Message Interface can test protective relays and other items , according to Megger. This device is capable of translating messages into a binary form. Binary is a method of communicating that consists of on and off messages.

Protective Covering

Testers must often used megger test kits in very rugged environments, according to Megger. When taking the test kit to a rugged environment, where there are adverse weather conditions that could damage the megger, the megger should be inside a protective casing.

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About the Author

Charles Pearson has written as a freelancer since 2009. He has a B.S. in literature from Purdue University Calumet and is currently working on his M.A. He has written the ebooks "Karate You Can Teach Your Kids," "Macadamia Growing Handout" and "The Raw Food Diet."