Master Key System Design: preparing for the visit

A new hire at the shop gets handed whatever spare key happens to be in the drawer, and it turns out to open the stockroom, the back office and the safe room all at once. The owner realizes nobody actually decided who should open what.

Worth answering before the call

Are any doors part of a shared or condominium-controlled building system? Roughly how many doors need to be part of the system? Are new departments, hires or locations expected in the near future?

What is tested before the keys are handed over?

Every cylinder is tested on the bench against its assigned keys, then again once installed: the change key on its own door, the relevant sub-master across its whole group, and the top-level master across every door in the system. Any lock that responds to a key it should not is corrected before handover rather than left for the owner to discover later.

Who should hold the top-level master key?

As few people as the business can genuinely operate with. Every additional holder is another way a full-access key can be lost, borrowed or copied without anyone deciding that should happen. A useful test during design is asking, for each proposed holder, whether they need to open every single door on the property or only a defined group; the second answer usually points to a sub-master instead.