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Electrical Testing
Fuse photo VvoeVale/iStock/Thinkstock

Tip of the Week: Don’t Blow it on the Measurement Front

Digital multimeters typically have special types of fuses; to ensure safety, make sure your replacement fuse is the right kind.

Any good digital multimeter (DMM) has a fuse. It may be annoying if this fuse opens while you’re attempting a measurement. But that fuse may have just saved your life. Follow these do’s and don’ts so you’ll be able to head home in one piece after your shift is complete.

Fuse Photo
Photo credit: VvoeVale/iStock/Thinkstock



• Replace it with just any fuse of the same rating. DMMs typically use a special type of fuse. The reason? This fuse is not for circuit protection, but for your protection.
• “Just for now” jumper around it so you can complete the task and go home.
• Replace the fuse and then attempt the same measurement in the same way.


• Consult your DMM manual or the manufacturer for the correct fuse.
• If you really need to make that measurement now, borrow someone else’s DMM rather than use one that’s “just for now” jumpered.
• Try to determine why that fuse blew before you proceed. Were you using the correct test jacks on the DMM? What is the voltage where you are trying to measure? Is the connection appropriate for the intended measurement? Are metal enclosures properly bonded? If you can’t determine why the fuse blew, treat it as the proverbial canary in the mine. Look more closely at the equipment and the environment; the odds that it’s safe to proceed are not on your side.

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