Updated on 19 October, 2021
A test light, also known as a voltage tester, test light, or Mains tester is an electrical testing apparatus used to identify the existence of power in a particular component under test. This is often required in cases where a component must be shut down or disabled before certain tests can be performed to isolate the reason for the loss. These devices are often made up of a special type of bulb that gives off high levels of illumination used in completing testing. Normally the bulb has a varying voltage value that indicates the difference between light and darkness, thus giving the tester a visual indication that the component is experiencing loss of power. There are many different types of test lights available, with some offering much higher light output than others.
One example is a nine volt test light. This type works by comparing the voltage between the terminals to determine whether the circuit is suffering a power loss. If the circuit is operating fine, then there is no problem and the bulb will not produce any light. However, if there is a fault, then this will clearly show this in the results and will be required to be re-installed in the original working condition before continuing. The nine volt variety is typically used where short circuits or damaged wires are common causes for failed tests.
Another example is a five volt direct current (DC) test light. These work much like the nine volt variety, except that the power supply is not connected to the circuit, and therefore there is no way for the potential to affect the circuits ability to function when under load. When the load is removed, the bulb will begin to burn out and eventually burn down the whole electrical system. DC test lights use a constant current source to supply power, so they are safe to use even under heavy load conditions. However, they require that the circuit attached to the light be ground. It should have been constructed in such a way that there is no way for the potential of an electric shock to be present.
The last type of testing device is the multimeter. Many people are very familiar with multimeters, and many use them all the time, but not many people understand how they work. A multimeter can measure both voltage and resistance, which allows it to test any type of electrical device possible. While it cannot actually perform the function of a test light, it can provide information to the operator on the state of his or her wiring, and can help him or her diagnose the problem.
Many people don't know there are different types of testing lights, and don't seem to realize how important these different kinds of lights are for their particular applications. For example, there is a continuity tester which will check for continuity between the leads which are attached to the circuit being tested. This continuity is tested by shining a multimeter probe on and between the terminals. There will be either a positive or negative result, depending on whether or not the two conduct paths are connected. If the results are negative, the circuit is suffering from a short, and if the results are positive, the circuit is clean and safe to work with.
Another useful type of test light is the battery tester. This probe is connected to a battery, and uses an ampmeter to measure the current drawn by the battery. It also measures the maximum voltage that the battery can safely support. It has a special connection block to prevent other probes from detecting a false power supply. This connection block minimizes interference from other probes.
Last but certainly not least is the Ground Source Test Light, which is just the opposite of the multimeter probe. The difference is that the multimeter only looks at the wire that it is attached to, while the ground source will look at both the wire and the ground, determining whether the wire is conducting or not. With the ground source, a current meter is used as opposed to a multimeter. The difference is that the meter will determine whether the wire is carrying electricity or not. It is designed for people who may have some knowledge in electronics, but are not so experienced with electronics.
There are a few different types of test light available to choose from. Each has its advantages and disadvantages. It is advisable that you conduct some research before buying one. You should buy a test light that will provide you with accurate and reliable readings. Your choice should be based on how it works, how difficult it is to install, how much it costs and how efficient the LED indicator is.