Electrical Tests

You can perform several simple electrical tests on all kinds of electrical things around your home. Electrical tests will help you perform electrical cord repair, hair dryer repair, motor repair, vacuum cleaner repair, as well as scads of other repairs. All you will need is one or more of three inexpensive testers: a continuity tester, a multimeter, and/or a circuit tester.

 Electrical Tests

These models are among the continuity testers (left), multimeters (middle), and circuit testers (right) available at hardware and electrical parts stores.

Continuity Tester

Electricity needs a continuous path or circuit in order to flow. It’s like a two-lane road from point A to point B and back. If one or both lanes are blocked, traffic–in this case, electricity–stops. A continuity tester is useful for checking cords and wires to make sure they can conduct electricity.

To test for continuity, follow these steps:

  1. Disconnect the cord from the power source (electrical receptacle). Make sure any switches on the device are on.
  2. Attach the alligator clip to one prong of the cord.
  3. Touch the tip of the continuity tester to the other prong. If there is continuity, the tester will light up. If not, it won’t.
 Electrical Tests

A continuity tester can tell you whether electricity can flow through a cord.

Here’s how it works: The continuity tester sends electricity from an internal battery through one cord prong and down the wires. If the light gets electrical current from the other prong it lights up, meaning that the path is good. Otherwise, something is stopping it. You can remove the cord from the appliance and test each of the two wires separately to see which one doesn’t work. If both work, the short is in the appliance itself. You can buy a continuity tester for less than $5.00.

Multimeter

A multimeter (also called a volt-ohmmeter or VOM) is another way of testing continuity. It also can measure the amount of alternating current (AC or household current) or direct current (DC or battery current) in a plugged-in or live circuit. It can check voltage, too.

 Electrical Tests

Analog multimeters measuring conductivity/resistance must first be adjusted for a zero reading. Check instructions that come with a new multimeter.

For example, a multimeter can verify that there are about 120 volts in an AC circuit or that a 9-volt battery is fully charged. In addition, a multimeter can check resistance. A continuity tester checks resistance, but answers yes or no. A multimeter checks resistance and reports how many ohms (the measurement of resistance) a circuit carries.

Fix-It Tip

Troubleshooting some devices may not even require that you use a multimeter. Many major appliances have fault codes that you can read and decipher using the owner’s manual. You press a button or two, read the resulting code, and look it up for repair instructions. And, if you don’t have the original owner’s manual nearby, we’ll show you where to find one later in Plan Your Project. Multimeters are relatively inexpensive. The analog unit shown was $10 and the digital multimeter was $20, though you can pay $50 or more for more accurate models. The ones shown here are sufficient for most electrical tests called for in the Fix-It Guides.

You can use a multimeter to test motors, switches, controllers, and many other electrical gadgets. Specific instructions will come with the multimeter you purchase.

 Electrical Tests

Connect the multimeter’s probes to the device.

Here’s how to use a multimeter to test an electric appliance:

  1. Disconnect the cord from the power source, except when testing a live circuit.
  2. Plug the test leads in to the multimeter.
  3. Select the function (ACV, DVC, resistance) and the range (maximum reading expected).
  4. Connect the probes to the cord or appliance component.
  5. Interpret the reading. The Fix-It Guides and the device’s owner’s manual will tell you what to expect–and what to do about it.
 Electrical Tests

The reading with the device on will show some, but not infinite, resistance. If it shows infinite, the switch or other internal component is bad (heating element, etc.) and disassembly is required to fix the problem.

Quick Test

Here’s a quick test you can perform on any electrical device without disassembling it. Use a multimeter or continuity tester to check the appliance’s continuity–ability to pass electricity from one plug prong to the other–when the switch is on. If it passes, the appliance is okay. If not, you’ll need to disassemble it further to find the problem.

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