A master key is a key capable of operating several different locks, each lock being operated by its own separate key (change key).
Many people think that they have a master key because they have one key which operates many locks in their home. In most cases these locks are just keyed alike and are not on a master key system.
If an apartment building has been master keyed, it allows one key to override all the locks in the system. For example, apartment 201′s key will not open 202′s lock but the master-key will open 201′s and 202′s lock and all other locks on the system. None of the individual apartment keys will fit each other but the master key will gain entry to all locks.
A good example of residential master-keying would be if the owner had a key that operated all the locks in their home (the master key) and had a separate key for the outside garage door. The separate key could be given to the gardener to access the garage for garden tools and supplies. However, the gardener’s key would not access the rest of the owner’s home.
You need to know if your home is on a master key system, so ask your builder, strata council or property manager if your lock has been master-keyed.
The dangers of this type of system are obvious, the worst being a lost master key. Strict control of the master key must be enforced. If a master key falls into the wrong hands the results could be devastating, resulting in theft with no signs of forcible entry, or worse yet – bodily harm.
Some builders are using a different type of master-key system. They refer to the master key as a “construction key”. This key is normally used by the builder’s personnel for a temporary period during construction. It operates all the locks designated for its use. The key is permanently voided by the contractor when the owner takes possession of the building.
One of the ways the contractor voids the key is to remove a plastic piece in the keyway that prevents his short construction key from operating the lock. The dangers to this type of master-keying system are remote but possible – the plastic piece being reinserted into the keyway making the construction key operable again.
All types of master-key systems involve placing master pins inside the cylinder of the lock. This compromises the security of the lock, making it easier to pick or manipulate.
Remember that master-key systems were developed strictly for convenience. So if you’re not sure if your locks have been master-keyed, get them re-keyed. And if you must master-key, consider installing high security locks as they will offer you a greater degree of security.