The 10 Best Multimeters
10. Innova 3320
9. Triplett 9007-A
8. Neoteck 8233D Pro
7. Mastech MS8268
6. Klein Tools 69149
5. Redfish Instruments iDVM 510
4. Extech EX330
3. Amprobe AM-560
2. Triplett 2030-C
1. Fluke 117
Multifunctional Measurements All In One
Whether you're a professional electrician or engineer, you know someone who is an electrician, or you just enjoy having gadgets around the house to help you assess and solve electrical problems with your appliances, then a multimeter is an integral tool to include in your arsenal.
Also referred to as a VOM (volt-ohm meter or volt-ohm-milliammeter), a multimeter is an all-in-one instrument that is capable of measuring several properties of an electrical circuit, mainly voltage (volts), current (amps), and resistance (ohms). Multimeters are available in either analog or digital types and are often designed for handheld use. An analog multimeter leverages the use of both a microammeter and moving pointer to display its readings. The microammeter is simply an instrument that measures small electrical currents.
By contrast, a digital multimeter (also known as a DMM or DVOM) features an easy-to-read numeric display that may also include a graphical bar representing the measured values. Because digital multimeters offer an increased level of accuracy and precision, they have become more common than their analog counterparts. However, analog multimeters are still useful, particularly if you're concerned about a rapidly-changing measurement that is more easily visualized using the analog display and pointer.
In addition to the meat and potatoes properties for voltage, current, and resistance measurements, some digital multimeters also contain circuits for continuity testing, diodes, and transistors. They are also capable of measuring additional electrical attributes such as capacitance and frequency.
Digital multimeters typically have three built-in sockets on their faces to which a test lead attaches. Although this may sound complicated, test leads are simply flexible, specialized, and fully-insulated black and red wires used to connect the multimeter to the circuit that's actually being tested or measured. The black test lead will always connect to the black socket (labeled COM for common), while the red test lead can plug into either of the remaining red sockets for measuring voltage and resistance or for measuring electric currents.
One of the most practical applications for a digital multimeter is determining electrical faults, which are defined as abnormal electrical currents. An abnormal current could take the form of a short circuit, so you'll know if that toaster you just bought could be problematic or if there is an underlying problem with your household wiring system and power supplies.
Additional functions for specialized multimeter applications include temperature measurements with a thermocouple probe, inductance, connectivity to a computer, and even the capability for the multimeter to speak a measured value aloud.
Safety First, Hazards Need Not Apply
Always exercise caution when dealing with electricity of any kind. I know this sounds rudimentary and simplistic, but remaining informed about the multimeter you choose (including its limitations and hazards) will help to keep you safe. Many multimeters are designed with varying levels of protection against common electrical hazards. When making a choice, one must be sure to understand the test equipment, its requirements, and how the equipment works.
It's vital to know the maximum voltage rating of the circuit, which is an evaluation based on research and experimentation that helps to determine how much voltage can be safely utilized by a particular device or form of wiring over its life. This is especially important when investing in a multimeter to ensure your testing does not exceed its maximum voltage limit.
Making sure your multimeter includes high-quality test leads is also an important factor to consider, since you will be handling them quite often and you don't want to risk electric shock. For that reason, ensuring the leads are properly insulated is definitely a good idea.
Many digital multimeters also feature bright, backlit screens, which come in handy if you have to work in dark places. Additionally, extra-long battery life should be a given if you're a professional electrician and plan to do a lot of testing.
Finally, while compact size comes with the territory of many digital handheld multimeters, finding one with a folding design can also provide additional protection for its sensitive sockets and components during transport.
A Brief History Of Multimeters
Invented in 1820, the galvanometer was the first moving-pointer, current-detecting device used to measure voltage and resistance with a Wheatstone bridge. However, the galvanometer was considered to be too slow and too delicate.
Dissatisfied with being forced to carry so many separate instruments required for the maintenance of telecommunications circuits, post office engineer Donald Macadie invented the first multimeter capable of measuring amps, volts, and ohms. At the time, it was referred to as an avometer (or AVO). Macadie brought this invention to the attention of the Automatic Coil Winder and Electrical Equipment Company (AWEEC) where it was put on sale in 1923. The best known model of the AVO series was the Model 8, which has remained virtually unchanged since its inception.
Today's digital multimeters have a strong focus on multifunctional use that includes computer connectivity and voice communication.