Safely Using DMMs

Safely Using DMMsThe digital multi-meter (DMM) is arguably the most useful device an electrician carries. But do you use yours safely?

Your first line of defense is to use only a quality, major American brand DMM. The cheap knock-offs lack the safety features of major American brand DMMs. An example is the terminal post spacing. Any major American brand DMM will have significant separation between the terminal posts. Cheap knock-offs typically pose an arcing hazard due to insufficient spacing.

You also need to be using a DMM that’s rated for the Category of use. Using a hobbyist’s Cat I meter on Cat III industrial busway is just asking for trouble. If you’re not sure whether a given DMM is suitable for the work you do, ask your electrical distributor for advice.

Assuming you’ve got the right DMM to begin with, follow these usage tips:

  • Connect it one lead at a time, using one hand only. Disconnect the same way. Connecting or disconnecting two leads at once can create an ionization path that sets up an arc blast. Using two hands creates a path across your heart.
  • Always work with a partner, not alone.
  • Focus on what you’re doing. Keep the cell phone off or leave the work area to use it.
  • Replace test leads that look even slightly worn or damaged.

Ensure accurate readings by replacing the battery if the battery indicator shows low battery, especially if you’re using the DMM to test for proper lockout.

Source: Mark Lamendola | Mindconnection

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