Door Entry and Access Control Systems: Wiring, Standards and Planning Considerations

Quick Answer: Video door entry systems use either 2-wire audio cable or Cat5e for IP video; electric door strikes operate at 12V or 24V DC (fail-safe or fail-secure). All wiring through fire-separating elements must be fire-stopped and, where required, run in fire-rated enclosures. IP-based systems are governed by BS EN 60839-11 for electronic access control and the Data Protection Act 2018 for any logged entry data.

Summary

Access control and door entry systems have evolved from simple audio intercoms to fully networked, camera-enabled, cloud-managed systems. IP-based door entry panels, biometric readers, and cloud access management are now standard in commercial premises and increasingly common in residential properties — particularly HMOs, flats, and residential developments. The range of products is vast, but the underlying wiring, power, and compliance requirements are consistent.

For tradespeople, the most important decisions are often made before any hardware is ordered: the cable infrastructure, power supply placement, and fire separation strategy will determine what is possible and what the ongoing maintenance burden will be. Getting these wrong means either expensive remedial work or a system that fails regulatory inspection.

This article covers video door entry wiring (2-wire audio vs IP video), door hardware (strikes, magnetic locks, and closers), power supply considerations, applicable standards, and the planning and GDPR implications that arise in multi-unit residential premises.

Key Facts

• 2-wire audio intercom — simple analogue systems; voice only; uses 2-core twisted-pair or standard bell wire; up to 100m run
• Cat5e/Cat6 for IP video — structured data cable; required for IP door entry panels, HD cameras, and PoE-powered devices; maximum run 90m to device
• Power over Ethernet (PoE 802.3af) — delivers up to 15.4W at the device; sufficient for most door entry panels and IP cameras; uses Cat5e/Cat6
• PoE+ (802.3at) — delivers up to 30W; required for PTZ cameras and high-power entry panels
• Electric strike — replaces the door keep (striker plate); electrically operated to release the latch; available in 12V DC and 24V DC
• Fail-safe strike — energised to hold locked; power loss opens the door (fire safety requirement for certain escape routes)
• Fail-secure strike — energised to release; power loss keeps door locked (security preference for entry doors not on escape routes)
• Magnetic lock (maglock) — electromagnet holds door closed; 500lb (227kg) or 700lb (318kg) holding force; always fail-safe (power loss releases door)
• BS EN 60839-11 — standard for electronic access control systems; defines performance requirements and test methods
• BS 7273-4 — standard for actuation of release mechanisms for fire and smoke control; controls how door hold-open devices interact with fire systems
• Planning permission — CCTV cameras on listed buildings and in conservation areas may require consent; HMO licence conditions may specify access control requirements
• GDPR/DPA 2018 — any access control system that logs named individuals must comply with the UK GDPR; requires a privacy notice, data minimisation, and retention limits

Quick Reference Table

Detailed Guidance

2-Wire Audio Systems

Traditional audio intercom systems use a 2-wire bus architecture that is simple to install and retrofit:

• The internal handset and external call panel are connected by a single pair of wires (twisted pair preferred)
• Power is supplied from a mains-powered transformer in the internal unit (typically 12V DC, 300mA)
• Simple 3-position switches at the panel (call, open, speak)
• Multiple apartments can be wired from a single external panel using a star topology with a riser cable feeding each floor
• Maximum practical run: 100m without a signal booster; use 0.75mm² twisted pair for runs over 50m

Multi-apartment wiring: In a block of flats, a standard riser cable (e.g. 10-pair or 20-pair cable) runs from the main door entry panel to each floor, with branch connections to individual apartments. Each apartment handset requires 2 cores. Many manufacturers supply bespoke riser cables for their systems.

IP Video Entry Systems and PoE

IP door entry panels use Cat5e/Cat6 cabling and receive power from the network switch via PoE:

• Install Cat5e or Cat6 to each door entry panel, access reader, and camera location
• Terminate to RJ45 (T568B standard) at patch panels and at all device connections
• Allow 90m maximum for horizontal cable runs (EIA/TIA 568B structured cabling standard); longer runs require a midspan PoE injector or a PoE switch closer to the device
• PoE budget: total power budget of the switch must accommodate all connected devices; a 24-port PoE switch with 370W budget supports about 24 devices at 15.4W each
• Separate the door entry system from the corporate network where security is a priority — use a dedicated VLAN

Advantages of IP systems:

• Remote management and monitoring via app or web browser
• Integration with cloud access control platforms (Verkada, Brivo, Honeywell)
• Video evidence storage (NVR/cloud)
• Easy addition of new entry points with only Cat5e cabling

Electric Strikes: Fail-Safe vs Fail-Secure

The choice between fail-safe and fail-secure strikes is a fire safety and security decision:

Fail-safe (normally energised, opens on power loss):

• Used on: fire escape routes, final exit doors, any door on a designated means of escape
• Required by Building Regulations Part B and BS 7273-4 for doors on escape routes
• Power consumption: continuous draw of typically 300–500mA at 12V DC; heat dissipation must be considered in the door frame

Fail-secure (normally de-energised, locked on power loss):

• Used on: entry doors to secure areas, server rooms, external access points not on escape routes
• Do not fit fail-secure on any door forming part of the means of escape
• Lower power consumption (only draws current when releasing)

Voltage and current: Most electric strikes are rated at 12V DC or 24V DC. The selection depends on the power supply available. 12V DC systems are more common in domestic applications; 24V DC offers lower current for the same power and better for long cable runs:

Magnetic Locks

Maglocks are surface-mounted electromagnets that hold a steel armature plate on the door:

• Always fail-safe (power loss releases door) — suitable for fire escape routes
• 500lb force: adequate for most internal doors and light-traffic entry points
• 700lb force: external access doors, higher security areas
• Power supply: 12–24V DC; draw is 300–600mA continuous
• Request-to-exit (REX) sensor required: a passive infrared or push-button device that releases the maglock when someone approaches from inside (required on any door that must allow egress)
• Door position sensor: normally fitted alongside maglock to monitor door state; feeds back to the access control system

Fire safety requirement: BS 7273-4 requires that maglocks on fire escape routes be connected to the fire alarm system so they release automatically when the alarm activates. This connection must be via a dedicated relay or input on the fire panel — not just the power supply.

BS 7273-4 Compliance

BS 7273-4 (Code of Practice for the Actuation of Release Mechanisms) applies to any electronically held-open or electronically locked door in a building with a fire alarm system:

• Electrically held-open fire doors must release on fire alarm activation
• Maglocks on escape routes must release on fire alarm activation
• The release circuit must be independent of the general power supply (typically a direct connection from the fire panel's door release output)
• Systems must be designed so that a single cable fault does not hold a door locked against escape

All access control wiring through fire compartment walls and floors must be fire-stopped. Use intumescent fire stopping products (Hilti FS-ONE, 3M FireDam) at all penetrations.

Wiegand vs OSDP Card Readers

New access control installations should specify OSDP readers where security of the door is important. OSDP v2 with AES-128 encryption prevents the cloning attacks that Wiegand is vulnerable to.

GDPR and Data Protection Act 2018

Any access control system that logs entry events against named individuals or stored card credentials is processing personal data under UK GDPR:

• Lawful basis: Legitimate interests is most commonly used for business premises and HMOs; consent may be appropriate for residential shared spaces
• Privacy notice: Occupants must be informed what data is collected, how long it is retained, and who has access
• Retention: Access logs should not be kept longer than needed — typically 30 days for routine access logs, longer only if there is a specific legitimate purpose
• CCTV: Video footage from door cameras is personal data; ICO guidance recommends a maximum 31-day retention for most applications
• Data subject rights: Occupants can request access to logs relating to their own entry data

HMO landlords adding access control are advised to include data processing information in the tenancy agreement and to post a clear notice at the entry point.

Frequently Asked Questions

What type of cable do I use for a door bell with video?

For a standard residential video doorbell (Ring, Nest Hello, etc.) running over your home Wi-Fi: only a 2-core power cable is needed (8–24V AC or DC as specified by the manufacturer), typically 0.75–1.0mm². For wired IP video entry panels in commercial or multi-unit residential: Cat5e or Cat6 for PoE power and data. For analogue video intercom panels: 4-core cable (2 for audio, 1 for video, 1 for screen activation) is typical.

Does an electric door strike need a separate power supply?

Yes. Electric strikes should not be powered directly from the access control panel's logic supply. The strike requires a dedicated power supply (transformer or PSU) rated for the continuous current draw. For fail-safe strikes, the power supply must run continuously; factor heat dissipation into the power supply location.

Do I need planning permission for a door entry camera?

In most cases, no. A camera mounted on a residential property facing the front door is permitted development. However: cameras on listed buildings require listed building consent; cameras in conservation areas covering public spaces may require planning permission; cameras aimed primarily at the public highway are discouraged by ICO guidance. Always check with the local planning authority for listed or conservation area properties.

What happens to a maglock in a power cut?

A maglock always fails safe — power loss releases the door. This is a fundamental design requirement. For premises where security is critical during a power cut, a battery-backed power supply (UPS) should be installed on the maglock power circuit. The UPS provides typically 1–4 hours of backup power. This does not affect the fire safety requirement — the fire panel connection must still override the UPS in an alarm condition.

Can I run access control cable alongside fire alarm cable?

Fire alarm wiring must comply with BS 5839-1 and uses dedicated Enhanced Fire Protection (EFP) cable. Access control wiring is not classified as fire-rated wiring and should not be run in the same conduit or trunking as fire alarm wiring, as any fault in the access control wiring could compromise the integrity of the fire alarm cable. Maintain physical separation of at least 300mm where parallel runs are unavoidable.

Regulations & Standards

• BS EN 60839-11:2013 — Electronic access control systems; requirements and test methods

• BS 7273-4:2015 — Code of practice for the actuation of release mechanisms; fire safety requirements for electrically locked and held-open doors

• UK GDPR / Data Protection Act 2018 — personal data processing requirements for any system logging individuals' entry events

• Building Regulations Part B — fire safety; escape route requirements relevant to door lock selection

• EIA/TIA 568B — structured cabling standard; cable installation and termination for Cat5e/Cat6

• IEC 62368-1 — safety standard for audio/video and information technology equipment; covers PoE-powered devices

• ICO CCTV Guidance — Information Commissioner's Office

• BSI BS EN 60839-11 — British Standards Institution

• BSI BS 7273-4 — British Standards Institution

• BSIA Access Control Guide — British Security Industry Association

• ICO: Data Protection and CCTV — Information Commissioner's Office

• kitchen circuits — circuit design and Part P requirements

• fire alarm systems — fire alarm integration with access control

• hmo licensing — HMO licensing and access control obligations for landlords