ISO classifications were used mainly in the 50’s, 60’s, and 70’s. The measurements ISO classified safes were based on barriers and thickness. For example, a safe composed of ½” thick steel would receive an extremely different classification compared to a safe composed of 1” thick steel encased in 8 inches of hardened amalgamate.
This method of safe classification seems logical, but in the late 70’s/early 80’s, British superior high-quality safes began to enter the market, it was apparent that a new method of testing would be necessary for the creation of comparable quality safes.
This is when the new method of testing began. Underwriter Laboratories (UL) rated safes based on performance, rather than simply the measurement of the thickness of a barrier, or the requirement to follow specific minimal requirements for a certain rating.
This being the case, UL allows for variety in safe barriers, and allows safe manufacturers to get creative when trying to create an effective barrier.
For example, UL guidelines would not require a safe simply to be composed of 1/4″ thick steel in order to achieve a “B” rating; instead they test the physical qualities of a safe by actually trying to crack the safe. After all, no one cares how thick your safe is if a criminal can get into it simply by cutting off small hinges.
UL rates safes based on how long it takes their safe-cracking experts to get into the safe. A TL-15 rating, for example, means that using tools, it takes UL safe crackers 15 minutes of actual attack (touching the safe) to successfully get into the safe (a 15 minute attack can really last over an hour). When a tool is not touching a safe, the clock stops – this keeps the attack times consistent but can make buyers somewhat confused. Unlike a criminal who is attacking blindly, UL receives detailed plans of the safe and for the safe 2 weeks they devise the best plan to break into a safe. Therefore, even if the criminal does have the proper skills and tools, it can take a criminal much longer (many hours at times) to actually break into the safe when you consider adrenaline and real-time reaction.
Want to learn more? Click here to read all about UL ratings.