What do UL fire ratings mean for vertical file cabinets?

UL (Underwriters Laboratories) fire ratings for filing cabinets indicate how long the cabinet's interior will stay below the critical temperature during a standard fire test. Key ratings: Class 350 (paper-rated) — interior stays below 350°F for the rated duration (1-hour, 2-hour) protecting paper documents. Class 150 (for microfilm/microfiche) — interior stays below 150°F. Class 125 (for digital media like hard drives, USB drives) — interior stays below 125°F. Most standard fireproof filing cabinets carry a Class 350 / 1-hour rating. Paper ignites at 451°F, so Class 350 provides a meaningful safety margin. For digital media protection, you need a Class 125 media safe, not a standard filing cabinet. FindOfficeFurniture.com carries fireproof options — call 888-719-4960.