Ratings are the most useful facts on a safe's spec sheet, and the most confusing. There are two families, fire ratings and burglary ratings, and within each family it matters a great deal who did the testing and how.
This guide explains the ratings you'll see most often. If a spec sheet doesn't make sense, call us at (330) 422-3991 and we'll help you read it.
Fire ratings
"Fireproof" is not a rating
No safe is fireproof. A fire rating says a safe kept its interior below a set temperature for a set time under specific test conditions. The useful questions are always the same: how long, how hot, what interior limit, and who tested it.
UL 72: the independent standard for record protection
UL 72 is UL's standard for the fire resistance of record protection equipment, such as fire safes and fire-resistant file cabinets. A UL 72 rating is written as a class plus a time, for example "Class 350, 1 hour."
The class is the highest temperature allowed inside during the test:
- Class 350: interior stays below 350°F. Intended for paper records.
- Class 150: interior stays below 150°F, with a humidity limit as well. Intended for paper plus media such as magnetic tape and photographic film.
- Class 125: interior stays below 125°F, with a humidity limit. The strictest class, originally written for computer disks. It's the class to look for when you store digital media such as hard drives and USB drives.
Standard durations are 1/2, 1, 2, 3 and 4 hours.
How UL 72 testing works
- Fire endurance test. The unit is heated in a furnace that follows a standard time-temperature curve, which keeps climbing as the test goes on. It reaches about 1,550°F at 30 minutes, about 1,700°F at 1 hour and about 1,850°F at 2 hours. The interior temperature is monitored throughout.
- Explosion hazard test. The unit is exposed to a furnace at about 2,000°F to check that sudden, intense heat doesn't make it burst.
- Fire and impact test. For units rated for impact resistance, the heated unit is dropped 30 feet, then reheated, and the contents are checked. This simulates a safe falling through a burning floor.
Not every test applies to every classification, so read the exact rating on the label. A UL label is usually inside the door, and you can confirm a listing in UL's online certification directory.
ETL Verified fire ratings
ETL is the certification mark of Intertek, an independent testing laboratory. An "ETL Verified" fire rating usually means Intertek checked that the safe meets the manufacturer's own stated claim, for example "60 minutes at 1,200°F, interior below 350°F."
That is genuine third-party verification of the claim, but the test conditions are the ones the manufacturer specified, not necessarily UL 72's rising furnace curve. Intertek can also test to published standards, so check whether the label names a standard or only states a time and temperature.
Manufacturer ratings
Many gun safes and home safes carry fire ratings from the manufacturer's own testing. These can be useful for comparing models from the same maker, but they aren't independently verified, and test methods differ from one manufacturer to the next.
Why the numbers don't line up
A UL 72 "Class 350, 1 hour" rating and a "60 minutes at 1,200°F" claim are both legitimate, but they describe different tests, so you can't compare them directly.
- Furnace temperature. UL 72's furnace climbs to about 1,700°F by the one-hour mark. A 1,200°F claim describes a lower peak exposure.
- How the heat was applied. A single time and temperature on a label doesn't tell you whether the furnace started cold or preheated, or how long it held the peak.
- Where temperature was measured. Results depend on where the sensors sat, both in the furnace and inside the safe.
- After the fire. Heat keeps soaking into a safe after the flames are out. Ask whether the interior was monitored during cool-down.
When two safes are rated by different methods, compare like with like or call us and we'll ask the manufacturer for the test details where they're available.
Choosing a fire rating
- Paper only: a Class 350 rating, or a verified rating with a 350°F interior limit.
- Digital media: a Class 125 or digital-media rating, or a separate media-rated container inside a larger safe.
- Longer ratings give you more margin if fire crews may take longer to reach you, or if the safe could end up under burning debris.
- Water from hoses and sprinklers is a separate risk. Water resistance is a separate claim, often ETL Verified, and isn't part of a UL 72 fire class.
Burglary ratings
What "net working time" means
Timed burglary ratings count net working time: only the time tools are actually working on the safe. The clock stops while testers change tools or plan the next step. These are lab results from trained technicians who know the safe's construction, not a prediction of how long a real break-in would take.
UL 1037 RSC (Residential Security Container)
RSC is the most common independent burglary rating on residential gun safes and home safes. It comes from UL 1037, and the 2016 edition of that standard split it into three levels.
- Level I (the classic "RSC" rating): one technician has 5 minutes to open the door or make a hand-size opening (about 4 inches across) in any surface. Tools are limited to common hand tools such as hammers with heads up to 3 lb, pry bars, chisels, punches, screwdrivers and wrenches, with no hand tool longer than 18 inches, plus an electric drill with bits up to 1/4 inch.
- Level II: two technicians, 10 minutes of net working time, and more aggressive tools including picking tools, grinding points, drills up to 1/2 inch and pressure-applying devices. The safe must resist opening the door or making a 6-square-inch opening through the door or front face.
- Level III: two technicians, 10 minutes, the Level II tools plus abrasive cutting wheels and power saws, and the maximum allowed opening shrinks to 2 square inches through the door or body.
Portable Level I containers are also drop-tested onto concrete. Level II and III containers must weigh at least 750 lb or come with anchor hardware and anchoring instructions, and must use a UL-listed lock. An RSC rating says nothing about fire. Fire protection is rated separately.
B-rate and C-rate: construction descriptions, not tests
B-rate and C-rate are insurance-industry labels that describe how a safe is built. No lab attacks the safe, and no single organization enforces the definitions, so they vary between manufacturers.
- B-rate is commonly described as a steel box with a lock, with a body less than 1/2 inch thick and a door less than 1 inch thick. In practice, many B-rate bodies are well under that limit.
- C-rate is commonly described as a body of at least 1/2-inch steel and a door of at least 1-inch steel.
Use these labels to compare construction, not tested attack resistance. If your insurance coverage depends on a safe rating, ask your insurer which ratings they accept before you buy.
UL 687 TL-15 and TL-30
UL 687 covers burglary-resistant safes, the commercial-grade ratings used for jewelry, cash and other high-value contents. "TL" stands for tool-resistant.
- TL-15: technicians attack the door and front face for 15 minutes of net working time using tools that include common hand tools, power drills, punches and pressure-applying devices. The safe passes if they can't open the door or make a 6-square-inch opening.
- TL-30: the same idea with 30 minutes of net working time and a broader set of tools, such as abrasive cutting wheels and power saws.
- X6 ratings (TL-15X6, TL-30X6): all six sides are tested, not just the door and front face.
- TRTL ratings add cutting torches to the tool list.
TL-rated safes also have to meet construction minimums, including a UL-listed lock, body walls equivalent to at least 1 inch of steel, and either a minimum weight of 750 lb or anchoring instructions. They are heavy, and delivery and placement need more planning.
Lock ratings
Locks are rated separately from the safe. Mechanical dial locks are rated under UL 768, where Group 2 is the common grade and Group 1 offers higher resistance to manipulation. Electronic locks are listed under UL 2058, UL's standard for high-security electronic locks, and many listed keypads are marked "UL Type 1." The exact listing for a given lock can be checked in UL's certification directory.
How to read a spec sheet
- Find the tester. Does the rating name a UL standard, say ETL Verified, or come from the manufacturer?
- Read the fire numbers: duration, outside temperature and interior limit.
- Find the burglary rating: RSC level, TL rating, or none.
- Check the lock and its rating.
- Check the construction: steel thickness for the body and door, bolts, hard plate and relockers.
- Look for the label. Independent ratings are usually shown on a label inside the door.
For help choosing, see How to Choose a Gun Safe, or browse fire safes, gun safes and home and office safes.
Questions?
Call (330) 422-3991 or email contact@ironwardsafes.com. We're available Monday through Friday and reply to calls, emails and messages within one business day.