So 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:
- Select the meter function.
- Select the highest range.
- 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.
- Read the display. Change the range, if needed.
- Remove the leads in the reverse order of connection.
Source: Mark Lamendola | Mindconnection