What Do We Mean By “Low Voltage Testing?”

You’ve heard of Low Voltage tests, but you may not understand what that means. What is the difference between low voltage tests and continuity tests? What tests do low voltage testers perform? Why would you want a low voltage tester when you can use a digital multi-meter?

When Cirris talks about “Low Voltage Testing” we usually mean all of the following tests:

• Continuity/Opens: Some people use the term “continuity” as another word for low voltage tests, but it is only one part of low voltage testing. Basically this test asks the question, does current flow from one point to another?
• Shorts: This test asks if current flows to any destination other than the expected test points.
• Components: This test asks if the components inside the device are present and that they measure the expected value.

Why not just use a hand meter?

Automated testers, like those built by Cirris, can perform all of these tests with low voltage. A digital multi-meter can determine errors like shorts, opens, and miswires. The time it takes to perform low voltage testing with a hand meter compared to an automated tester is like the difference between plowing a field using a hoe compared to using a tractor to do the work. Both tools can do the job, but one will be faster and more efficient.

When using an automated tester, the low voltage test can perform all the tests mentioned above for a simple device in seconds. The tester will measure each wire automatically to find errors fast. Imagine how many cables can be tested on an automated tester in the same amount of time it takes to test one cable with a digital multi-meter.

How does low voltage testing work?

Low voltage testing is able to catch errors such as shorts and opens by applying current to a wire and measuring the voltage. The wire will have a current affected by several factors including resistance and components. If the wire is connected correctly, the test will read low resistance. That means current is flowing through the wire as expected and reaching the required connections. If the tester reads high resistance it means something is impeding the current from reaching its destination. This could be caused by a number of causes.

• The problem may be an open, meaning the connection isn’t secure and the current can’t reach the destination.
• The problem may be caused by the wire being connected to the wrong point. This error is often known as a miswire.
• Another reason for the error could be the tester settings are wrong.

Why does the tester ask for resistance settings?

When setting up for a low voltage test, some of the parameters can get confusing. For example, Cirris testers ask for resistance measurements when creating a low voltage test.

Resistance is everything that inhibits the current. Each wire naturally has some form of resistance that restricts the current. In order to get an accurate measurement, the tester needs to know what resistance to expect. If these settings are entered incorrectly, the tester may report an error when the problem is simply a resistance level set too low or too high.

These measurements should be made clear in the cable instructions or specifications. If the cable instructions don’t specify what resistance measurement is needed for the test, you can still determine what value will work using Cirris’s Wire Resistance Calculator. This calculator allows you to input certain factors from your wire that cause resistance. The resulting value can be used to set resistance thresholds for low voltage tests.

Cirris has an article to help you understand resistance thresholds. You can learn more about these topics in the Cirris Learning Center.

Further Reading:

Resistance Is NOT Futile

How to make your tester live longer

Which Tester Should I Buy