Electrical cords are simple in operation and simple to test and replace.
Using a continuity tester to check an attached power cord. Make sure the appliance's switch is ON.
Touch probes to the plug prong and one of the female plug ends to determine if there is continuity.
An infinite reading on the multimeter indicates that there is a break in the cord[md]or that you're not testing both ends of the same cord wire.
One of the most common things in your homeand one of the most common to need fixingis the electrical cord. That list includes cords on large and small appliances, electric tools, electric clocks, computers and printers; anything that gets its power through an electrical outlet in the wall. That means knowing how to fix electrical cords is important to knowing how to fix lots of things in your home!
A cord is a small flexible insulated electrical cable with a plug at one or both ends that connects an electrical device with a source of electricity. There is a wide variety of cords, each with wires and plugs designed to carry a specific electrical load.
Cords and plugs can break. Through repeated use, they can develop shorts and stop delivering electricity to the device that needs power. Fortunately, they are relatively easy to test and repair or replace.
To test an attached 120-volt power cord:
Unplug the appliance or device.
Disassemble the device to access the cord terminals. Unclip, unscrew, or desolder the cord's connectors from the device. If there is a loop or strain-relief fitting, remove it.
Set your multimeter ohmmeter on RX1 (resistance times 1) scale. Or you can use a continuity tester (see Using a Continuity Tester)
Clip a jumper wire across the cord leads (or twist the two wires together). Clip or touch the meter's probes to the plug prongs. The meter should read zero ohms.
Bend and pull on the entire cord. A steady zero-ohms reading means the cord is OK. A high or fluctuating reading means the cord is faulty and should be replaced with an exact duplicate.
To test a removable cord for continuity:
Unplug the appliance.
Set the multimeter on the RX1 scale. Or you can use a continuity tester.
Clip a jumper wire across the male plug and insert the test probes into the female plug.
Bend and pull the cord along its entire length. If the meter reads zero ohms (no resistance to the flow of electricity), the cord is good. A high or fluctuating reading means there is an open circuit. Replace the cord and/or the plug.
To replace a power cord:
Unplug the appliance.
Remove the old cord.
Remove insulation from the new cord if necessary (see below).
Connect new cord leads to appliance leads or terminals.
To remove insulation from ("strip") a cord or other electrical wire:
Insert 1/4 in. of the tip of wire into the corresponding hole in the jaws of an electrical wire stripper tool.
Close the tool to cut and remove insulation from the end of the wire.
Verify that the insulation is cleanly cut and removed from the wire. If not, repeat the process using a larger or smaller gauge hole in the stripper tool.