Imagine working in a school with more than 50 doors to open and close every day (each with a different lock) and only one person to do all that work. Carrying 50 keys would be extremely complicated — which is exactly why master keying was invented. Every lock has its own combination, and in addition to opening with its own key, it can also be opened with the master key, making the job of the person in charge much easier.
There are several types of master key scheme, divided into groups according to key type.
Key equalisation
A single key design opens all locks in the scheme — a simple plan ideal for homes with several interior locks or small commercial premises where time savings are desired.
Simple master keying
All locks open with a master key as well as their own individual keys. The ideal method for medium-sized offices, companies, etc. and one of the most requested systems.
Common areas mastering
This type is characterised by having several key types — for instance, in a residential community, keys for block A, block B… — that open their own doors plus the common areas, and can also open private areas or flats.
Group mastering
In this scheme locks are divided into groups, each with a group master key plus individual keys. Above all groups sits a "grand master key" that opens every group without distinction. This system is ideal for hotels — floors can be separated — or office buildings divided by company.
Cross mastering
Perhaps the most complex scheme available: several master keys open locks across multiple groups while having restricted access to other groups. It requires extensive planning and control of the key-and-lock diagram to avoid any mismatches.
