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Digital multimeters have become a common presence in electrical contractors’ toolboxes. These handy, portable instruments can have a broad range of testing capabilities to help electricians troubleshoot common electrical problems, from faulty switches to more complicated panelboard issues.

Measuring Your Options: How to Choose a Digital Multimeter

Chuck Ross
Digital multimeters have become a common presence in electrical contractors’ toolboxes. These handy, portable instruments can have a broad range of testing capabilities to help electricians troubleshoot common electrical problems, from faulty switches to more complicated panelboard issues. In fact, the number of options available with multimeters can make choosing the right model a challenge. I turned to Lee Newson, product manager with multimeter manufacturer Sperry Instruments, to get some tips on what to look for.

One big dividing line in the digital multimeter universe is between automatic-ranging models and those requiring manual range-setting. With auto ranging, a multimeter automatically detects the electrical characteristic being measured and the range within which measurements should fall. With manual-ranging meters, however, the user has to select the appropriate range.

Each of these approaches has its advantages, Newson said. The auto range detection feature “removes the need to have to adjust for anything yourself and is simpler to use for beginners.” Manual products require a bit more expertise, “but they also provide a more accurate measurement, since the measured value won’t fluctuate between ranges making them ideal for professional use where accuracy is important. Manual-ranging meters are also typically less expensive than auto-ranging meters.”

Next, Newson targets three features or sets of features he thinks contractors should consider when making their next digital multimeter purchasing decision.

  • True RMS. According to Newson, True RMS (root mean square) enables meters to measure AC current and voltage more accurately. “A True RMS meter is going to be more accurate but also more expensive. It is an important feature for professional use when accuracy is important.
  • Measuring capabilities. Almost all meters measure AC/DC voltage and resistance, but higher-end products often can target characteristics more complicated projects might require. “For example, many meters are also capable of measuring AC current, DC current, continuity, diodes, frequency, batteries and more. These are optional feature that may be necessary for certain jobs. 
  • Data saving options. Features like data hold and min/max measurement make data recording easier by saving the data. Data hold freezes the display to show the last recorded value, while min/max does the same thing to show either the lowest or highest recorded data value. “These specifications make it much easier to identify data fluctuations.”
Photo courtesy of Sperry Instruments
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