How adequate is a product rated for only one hour when most fires last much longer?
A typical fire burns at around 800°F. As it passes through the building, the fire’s intensity changes as flammable items are consumed. Fires usually average only 20 minutes in any location. This intense burn is comparable to the burn portion of the UL test. After the flammable items are consumed in the fire, the overall temperature decreases, leaving items inside the fire to absorb the radiant heat. This part of the fire is comparable to the cool down portion of the UL test. Depending on the product being tested, the cool down portion of the test can last as long as 15-25 hours, during which the internal temperature and humidity levels cannot exceed the standards set forth by the test. Most products that fail the UL test fail during this cool down period. Be wary of marketing hype that says “tested to UL standards” – tested doesn’t necessarily mean the product passed the test. A one-hour rating means the product will also survive the cool down period.