The Knox Box system is a commerical box (safe) that is installed on the exterior of an occupancy (both residential and commerical) for the fire department to gain access to that building when there is no one available to allow them to enter. Inside the Knox Box are the keys needed to enter the occupancy. Only an electronically controlled and recorded signal allows the firefighters to gain access to the key to open the Knox Box.
This prevents the fire department having to damage a building while trying to gain access to it in a non-life threating emergency.
Under the Town of Salem Municipal Code Chapter 187 - Fire Prevention Section 187-12 Key Vault requires that any building that has a sprinkler system, fire alarm system or firefighter elevator recall shall be required to have a Knox Box system in place.
Residential Knox Box units can be purchased for residental use as well.
Further questions about the Knox Box program can be directed to the Fire Prevention Office at 603-890-2009
Official Knox Box website