Testing: Some DMM Uses

Testing: Some DMM UsesSo you were smart and bought a brand name digital multimeter (DMM) with industry-standard safety features, certifications, and measurement capabilities.

But do you recognize the limitations of its various functions? These include:

  • Resistance testing function. This is a DC voltage at a level that isn’t suitable for performing insulation resistance tests on conductors. Nor is it suitable for determining connection resistance.
  • High-low recording function. It can’t capture data with the granularity that a power analyzer does.
  • Current measuring function. If you look at the test leads and the input fuse, you can see this is a very limited capability. For industrial current measurements, you need a current probe or a different instrument.

For industrial settings, the primary use of the DMM is for making voltage measurements. Among the uses for making these:

  • Verify de-energization for lockout/tagout.
  • Verify the presence of supply voltage.
  • Determine if a fuse blew or a breaker opened.
  • Track down wiring errors.

Because DMMs are so useful, electricians tend to use them often. But do you use yours safely? Here’s the correct sequence of steps for safely making a voltage measurement:

  1. Select the meter function.
  2. Select the highest range.
  3. Using one hand, connect the black lead. Using the same hand, connect the red lead. As a habit, make connections the same way every time.
  4. Read the display. Change the range, if needed.
  5. Remove the leads in the reverse order of connection.

Source: Mark Lamendola | Mindconnection

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