Door Access Control Systems

Four things to decide for each door

Every door with access control comes down to four questions. How will people prove who they are: a fob, a card, a PIN code, a fingerprint or their face? What keeps the door shut? Here, that’s a magnetic lock, chosen by how hard it holds. How do people get out? You need an exit button or another request-to-exit device on the inside, and that’s a must, not an extra. And where is the decision made: in a keypad at the door, or in a controller that runs several doors from one list of users?

Choose your fob type before you buy anything. 125kHz fobs (EM4100/EM4102, sometimes labelled “proximity” or “ID”) are cheap and very common, but they send out a fixed number that a cheap copier can clone. 13.56MHz fobs (MIFARE / NFC, ISO14443A) use an encrypted exchange, and they’re what you want on any door protecting stock, cash or a block of flats. A reader only works with the frequency it was made for. If you’re adding fobs to an old system, check the reader first: the two kinds look the same and won’t work in each other’s readers.

Choose the magnetic lock to suit the door, then line it up properly. The holding force on the box assumes a straight pull with the metal plate (the armature) sitting perfectly flat against the magnet, so a bracket that gets the plate flat does more than buying the next size up. A pair of doors needs a twin lock that holds both. An outdoor gate needs a weatherproof lock: an indoor one fitted to a gate will corrode within a season.

Magnetic locks are fail-safe by nature: if the power goes off, the door opens. That’s exactly right on an escape route, but it means a maglock is the wrong lock for a store room or comms room that has to stay locked through a power cut. If the door is on a fire escape route, how it releases (an emergency release in the lock’s power line, and often a link to the fire alarm) is a question for your fire officer, and it needs settling before you choose the lock.

Got more than a couple of doors? Use a controller. A keypad on its own keeps its own list of users, so when someone leaves you have to visit every door with the master card. A controller keeps one list and records who opened which door and when. It can also send a dry-contact signal to an alarm input on your NVR, so each door event is marked on the CCTV footage, which is the most useful link-up you can have on a small business site. If you’d rather give staff printed ID cards than fobs, the card printer in this range prints them in-house. Printing doesn’t encode the card, though, so use printed cards alongside fobs, or choose a printer that can encode.