So you’re the proud owner of a new digital multimeter (DMM). This one has a low impedance filter, a feature you’ve wanted for a long time. This means no more ghost readings! But do you know how to use your new DMM safely?
Between OSHA and NFPA 70E, you might think all the safety issues are covered. But what happens if you go to Panel 1017G instead of Panel 1007C? Both panels conform to the safety requirements employers must meet. Your particular DMM is rated for 1,000V. Panel 1007C contains 480V bus, so no problem there. But Panel 1017G is a medium-voltage panel. It contains a 4,160V bus.
Before you open any panel door, always read everything posted on the panel cover. Look for something that tells you what voltage level of equipment you can expect to find. If it’s not clearly marked, don’t open the panel. Find another way to verify the expected voltage.