Door Access Control Systems — Trade Supply

Specifying a door access system that will not come back

Every door needs four decisions: how people identify themselves (fob, card, code, phone or fingerprint), what holds the door (maglock, electric strike or motorised lock), how it releases in an emergency (break-glass, request-to-exit button, fail-safe or fail-secure), and where the decision is made (a standalone reader at the door, or a controller in a cupboard). Get the fail mode wrong and the door either traps people or unlocks in a power cut, which is the fault most retrofits are called back for.

Credential frequency is the second trap. 125kHz (EM/Proximity) fobs are cheap and universal but trivially cloned; 13.56MHz (MIFARE/DESFire) costs a little more and is what to fit anywhere the credential controls money, stock or a residential block. The two are not interchangeable, so read the frequency on the existing reader before quoting fobs for an extension of an old system.

For anything past a handful of doors, put the decision in a controller rather than the reader: standalone readers keep their user list at the door, so removing a leaver means visiting every door. A controller keeps one list, logs who went where, and integrates with the intruder alarm and the CCTV recorder for event-linked footage — the reason most commercial specs land there.