🔒 Safe Rating Guide (UL Fire & Burglary)
Cut through the alphabet soup of safe ratings. Filter UL fire ratings (Class 350, 150, 125) and burglary ratings (RSC, TL-15, TL-30, TL-30x6) by what you actually need to protect against.
🔒 Matching UL ratings
Keeps the interior below 350°F for a 1-hour furnace exposure (exterior driven to roughly 1,700°F), then survives a cool-down. Paper chars near 400°F, so Class 350 is the paper-document standard.
Keeps the interior below 350°F for a 2-hour furnace exposure. The extra hour matters for larger buildings or slower fire-service response.
Keeps the interior below 150°F for a 1-hour exposure. Magnetic tape and film degrade well below paper's char point, so they need this tighter limit.
Keeps the interior below 125°F and relative humidity below 80% for a 1-hour exposure — the strictest fire class, for diskettes, drives, and other digital media.
Withstands 5 minutes of net working time against common hand tools (screwdriver, hammer, pry bar). The entry-level burglary rating carried by most home and gun safes.
Withstands 15 minutes of net working time on the door using hand and electric tools (drills, punches, pressure devices). A genuine high-security rating.
Withstands 30 minutes of net working time on the door, with a wider tool set including abrasive cutting wheels and power saws.
Extends the full 30-minute TL-30 tool test to all six sides of the safe, not just the door — protection that holds up no matter how the safe is approached.
Withstands 30 minutes of net working time on all six sides against tools AND an oxy-fuel cutting torch (the 'TR' prefix). A commercial/vault-grade rating.
A safe carries fire and burglary ratings independently — a good home safe often has both (for example a UL RSC burglary rating plus a UL Class 350 1-hour fire rating). “Net working time” counts only the minutes tools are actually in contact with the safe, so real-world break-in attempts take far longer.
Two ratings, two different threats
Fire and burglary are separate problems, and UL tests them separately. A fire rating (UL 72) tells you how long the safe keeps its contents cool enough to survive a blaze; a burglary rating (UL 687) tells you how long it resists a determined attacker with tools. A safe can be excellent at one and mediocre at the other, so read both labels.
Match the ratings to what you’re storing. Irreplaceable paper wants a Class 350 fire rating; cash, jewellery, and firearms want a meaningful burglary rating like RSC or a TL series. The best home safes carry one of each — and remember that “net working time” means a real break-in takes much longer than the rating’s minutes suggest.
❓ Frequently Asked Questions
What does a UL fire rating like 'Class 350 1-Hour' mean?
Under UL 72, the 'Class' number is the maximum interior temperature (in °F) the safe keeps its contents below while its exterior is driven to furnace heat for the stated time. Class 350 keeps the inside under 350°F — paper chars near 400°F — so it protects paper documents for, in this case, one hour.
What's the difference between Class 350, 150, and 125?
They protect increasingly heat-sensitive contents. Class 350 is for paper, Class 150 for magnetic media and film (which degrade below paper's char point), and Class 125 for computer data media, keeping the interior below 125°F and humidity under 80%.
What do burglary ratings like TL-15 and TL-30 mean?
Under UL 687, TL-15 and TL-30 mean the safe's door resisted a UL technician for 15 or 30 minutes of 'net working time' — time with tools actually against the safe. TL-30x6 extends that 30-minute test to all six sides, and a 'TR' prefix adds an oxy-fuel torch to the attack.
What is 'net working time'?
It's the clock UL uses for burglary tests: it counts only the seconds a tool is in contact with the safe. The moment a tool is lifted, breaks, or is swapped, the clock stops. So a 'TL-15' safe typically survives a real attack far longer than 15 wall-clock minutes.
Should a home safe be fire-rated, burglary-rated, or both?
Ideally both, because they defend against different threats. A common home safe pairs a UL RSC burglary rating with a UL Class 350 1-hour fire rating. Decide what you're storing — documents, cash, media, firearms — and choose a safe whose two ratings match those risks.