Access Control and Smart Locks: A Practical Guide for Offices, Hotels and Homes

In Depth

In Depth

Keys get copied, lost and never returned, and a notebook cannot tell you who opened the store room at night. This guide explains the choices in electronic access control, from credentials and locks to power cuts and fire exits, so you can plan before asking for quotes.

Note Extrion supplies and installs access control, smart locks and intercoms, and earns from sales and installation. No manufacturer paid for or reviewed this guide.

What access control does

Electronic access control gives each person their own credential, lets you decide which doors they may open and when, and keeps a record of every opening. When someone leaves, you remove their access the same day instead of changing locks. The tutorial above walks through a typical system; the sections below explain each choice.

The parts of a system

• Credential: what the person presents, such as a card or key fob, a PIN, a fingerprint, their face, or a phone app.
• Reader or terminal: the device at the door that reads the credential.
• Controller: decides whether to open the door. In small systems it is built into the terminal. Larger or higher-security sites use a separate controller on the secure side of the door, so that someone who removes the reader outside cannot use its wiring to open the lock.
• Lock: the hardware that holds the door, such as a magnetic lock, an electric strike or a motorised lock.
• Exit device: a push button, a handle or a request-to-exit sensor so people can leave.
• Power supply with battery backup.
• Software: to add and remove users, set schedules and read the access log, either on a local computer or in the cloud.

Choosing the credential

Many sites combine them: cards for visitors and contractors, fingerprint or face for staff areas, and two credentials together for server rooms or cash offices.

Tip Ask the supplier which card technology the system uses and whether the cards are encrypted. Some older proximity cards can be copied with inexpensive equipment, which defeats the point of issuing them.

Choosing the lock

• Magnetic lock (maglock): an electromagnet on the frame and a steel plate on the door. Strong and simple, and it is always fail-safe: with no power there is no magnetic hold. Common on glass and aluminium doors.
• Electric strike: replaces the strike plate in the frame, so the door keeps its normal lock and handle. Strikes are made in both fail-safe and fail-secure versions, and many can be switched between the two during installation.
• Motorised or smart lock: a lock body or cylinder with its own electronics, often battery-powered. Suits doors where running cable is difficult, such as villas, apartments and hotel rooms. Check how it warns of low batteries and whether it has a mechanical key override.

Fail-safe or fail-secure?

A fail-safe lock opens when it loses power; a fail-secure lock stays locked. This is not a quality grade, it is a decision about what each door should do in a power failure:

• Doors on escape routes must always let people out. A fail-safe lock does this when power fails. A fail-secure electric strike can also be acceptable, because the door's own handle still opens it mechanically from the inside, but the decision belongs to whoever is responsible for fire safety in the building.
• Store rooms, cash offices and server rooms are usually fail-secure, with a mechanical key override so authorised staff can still get in.

Agree this door by door, write it on the door schedule, and follow the fire safety requirements that apply to your building.

Fire exits and emergency release

A locked escape door that does not open in a fire is a life-safety failure, so magnetic locks and other fail-safe locks on exit routes are usually installed with several independent ways to release them. International model codes, such as the US International Building Code and NFPA 101, describe the common pattern for electrically locked egress doors released by a sensor:

• the lock releases when its power, or the sensor's power, fails;
• the lock releases when the building's fire alarm or sprinkler system activates, and stays released until that system is reset;
• a manual push to exit button near the door cuts power to the lock directly, without depending on the access control electronics.

These codes are not law in Tanzania, but they are a useful reference. The requirements that actually apply are set by the local fire authority and the building's fire safety design. In Zanzibar the fire service is the Zanzibar Fire and Rescue Force; we found no published Zanzibar rule on escape-door locks, so ask the force or your fire safety adviser before locking an exit door. Where a fire alarm is installed, the link between the fire panel and the access control power supply must be designed and tested by a competent installer. Our guide to conventional vs addressable fire alarms explains the panel side.

Warning Never bypass a push-to-exit button, wedge an exit door or disconnect a fire alarm release to stop a lock "misbehaving". Call the installer.

Power cuts

Power cuts happen, so plan for them:

• Fit lock power supplies with batteries sized for the locks and terminals, and test them.
• Decide, door by door, what should happen when the batteries run out.
• Put the controllers, network switch and any on-site server on a UPS so the log and remote management keep working.
• Keep a mechanical override for critical doors, and know who holds the keys.
• For battery-powered smart locks, replace batteries on a schedule rather than waiting for warnings.

Video intercoms and gates

A video intercom at the gate or main entrance lets staff or residents see and speak to visitors before opening. Indoor monitors, phone apps and a connection to the access system mean one press can open the gate, with the event recorded. The intercom's lock relay switches the lock power: magnetic locks are wired through the normally closed contact and electric strikes through the normally open contact. For gates, check the motor, the safety sensors and what happens during a power cut before choosing the intercom. If an existing intercom stops working, see IP intercom not connecting.

Hotels, offices and homes

• Offices: card or fingerprint readers on the main door and sensitive rooms, with schedules (cleaners only in the evening, contractors only on agreed days) and same-day removal of leavers.
• Hotels and guesthouses: guest-room locks usually work with cards encoded at reception for the length of the stay, separate from the staff and back-of-house system. Our guide to technology for hotels and guesthouses covers the wider picture.
• Villas and homes: battery-powered smart locks, a video intercom at the gate, and app access for family and staff. See wired vs wireless smart home automation.

Time attendance

Many access terminals also record clock-in and clock-out times. If you want attendance reports for payroll, say so at the start, because it affects which terminals and software are chosen and where they are mounted.

Network and security

Networked access control is a computer system, and it needs the same care:

• Put controllers and readers on their own network or VLAN, separate from guest Wi-Fi.
• Change default passwords, give each administrator their own login, and update firmware.
• For remote management, use the manufacturer's cloud service or a VPN; do not open router ports to the controller.

Planning checklist

1. List every door and gate, with a photo, the door type and who uses it.
2. Group people: staff, managers, cleaners, contractors, visitors, guests.
3. Decide the credential for each group, and the schedule for each door.
4. Choose fail-safe or fail-secure for each door, and the exit method.
5. Plan battery backup and, where a fire alarm exists, the fire alarm release.
6. Decide who will manage users, and how leavers are removed the same day.
7. Ask for user enrolment, administrator training and as-built records at handover.

When to call Extrion

If you are planning access control, smart locks or an intercom, see our access control and intercoms page or contact us. For locks and intercoms as part of a smart villa or office, see smart home and office automation.

This guide is general information. Procedures, product features and firmware change, so check your own equipment's documentation before you start.