Just found out my multimeter's CAT rating matters way more than I thought

I was looking up why a cheap meter blew up on a buddy during a house call (yikes) and stumbled onto an article from Fluke about CAT III vs CAT IV ratings. Turns out using a CAT II meter on a 480V panel can literally arc flash in your hand - that stat spooked me enough to check my own gear tonight. Anyone else ignore those ratings until something went wrong?

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1 Comment

paul_mason123h ago

Actually, CAT III is for distribution panels and building wiring up to 600V, which covers most residential and light commercial work. The real danger is using a CAT II meter on those circuits since it's only rated for outlet and appliance testing, not the high energy transients from big motors or utility faults. Glad your buddy is okay but yeah, those ratings are there for a reason and Fluke's site does a solid job explaining the difference.