A time-delay combination lock is most commonly a digital, electronic combination lock equipped with a delay timer that delays the unlocking of the lock by a user-definable delay period, usually less than one hour. Unlike the

time lock A time lock (also timelock) is a part of a locking mechanism commonly found in bank vaults and other high-security containers. The time lock is a timer designed to prevent the opening of the safe or vault until it reaches the preset time, eve ...

, which unlocks at a preset time (as in the case of a

bank vault A bank vault is a secure space where money, valuables, records, and documents are stored. It is intended to protect their contents from theft, unauthorized use, fire, natural disasters, and other threats, much like a safe. Unlike safes, vaults a ...

), time-delay locks operate each time the safe is unlocked, but the operator must wait for the set delay period to elapse before the lock can be opened. Time delay safes are most commonly used in businesses with high cash transactions. They are used in some banks including Nationwide, HSBC, Barclays, and Halifax.

Use

Time-delay combination locks are frequently incorporated into money safes as an

armed robbery Robbery is the crime of taking or attempting to take anything of value by force, threat of force, or by use of fear. According to common law, robbery is defined as taking the property of another, with the intent to permanently deprive the perso ...

deterrent. In many instances, time-delay combination locks are also equipped with a

duress code A duress code is a covert distress signal used by an individual who is being coerced by one or more hostile persons. It is used to warn others that they are being forced to do something against their will. Typically, the warning is given via some ...

which may be entered to activate the time delay whilst sending a silent alarm to a monitoring centre. Modern time delay combination locks can have many functions such as multiple different codes, pre-set time lock settings (open and close times), pre-set vacation times (e.g. Christmas Day), dual code facility, and a full audit trail providing a detailed record of the lock history showing who opened the lock, when and how long it was open. They also use a

non-volatile memory Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retain stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data. Non-volatile memory typic ...

so that no information is lost if the batteries are depleted. This will allow the safe to be opened when the batteries are changed after the pre-set time if the correct code is entered. Some electronic combination locks with a time-delay feature require the code to be entered twice: once to start the timer, and a second to unlock and open the safe entered after the delay period has expired.

References

Locksmithing Password authentication Access control {{Tech-stub