Choosing between a wired audio intercom and a video system is one of the more consequential decisions a managing agent or RMC board will make about a residential block. The technology lasts 15 to 25 years if properly installed and maintained, the installation affects every resident, and the cost difference between the two options is significant. This article covers how each type works, what the real-world differences are, and which option tends to suit which kind of property.
How Audio-Only Wired Systems Work
A standard wired audio intercom uses two conductors — or four on older installations — to carry power, audio and door release signals between the entry panel and each flat's handset. When a visitor presses a flat number on the entry panel, an electrical signal travels to that flat's handset to produce a call tone. The resident lifts the handset, speaks with the visitor through the shared audio circuit, and presses a button to trigger the door release.
Wired audio systems installed before 2005 typically use a four-wire bus where audio, power and door release run on separate conductors. Connection corrosion at terminal blocks and voltage drop on long cable runs are the most common fault points on these installations, particularly in blocks with cable runs over 30 metres from the panel to the furthest handset.
Modern two-wire audio systems are simpler to install and maintain: power and audio share the same pair, reducing the cable count and the number of connection points that can corrode or fail.
What Video Intercoms Add
A video intercom adds a camera at the entry panel and a screen at each handset, allowing residents to see who is at the door before deciding whether to admit them. The practical security benefit is meaningful: residents can identify an unexpected caller without having to speak to them or open the door, and can check that a delivery person or contractor matches who they claim to be.
Higher-end video systems integrate with door access control, allowing residents to release the door via a smartphone app, receive a notification when a visitor arrives, and review a log of entry events. These features are of most interest in blocks where security is a primary concern, or where a significant proportion of residents work irregular hours and receive deliveries at times when they are not home.
The principal technical limitation of video intercom is bandwidth. A video signal requires substantially more cable capacity than audio alone, which means that some existing cable runs are not suitable for a video upgrade without full or partial rewiring. Whether a block's existing cable infrastructure can support video is one of the first questions an engineer needs to answer before a video system can be specified.
Installation Disruption in an Occupied Block
Replacing an audio system on a like-for-like basis, using the same cable routes, is relatively low-disruption. The entry panel and handsets can usually be changed flat by flat, with each flat out of service for one to two hours during its handset swap. The block is never entirely without door entry because only one flat is being worked on at a time.
A video upgrade from an audio installation is more involved. If the existing cabling cannot carry video, new cable runs are needed. In a multi-storey block this typically means access to riser shafts, cable ducts, or surface trunking along corridors, all of which require residents to be informed in advance and may require scaffolding or specialist access equipment in older buildings.
The Building Safety Act 2022 introduced formal accountabilities for responsible persons in multi-occupancy buildings, and managing agents are increasingly expected to document risk assessments for works affecting building access, including the period during which a replacement is being installed and the entry system is temporarily impaired.
Cost Comparison Over 10 Years
For a 20-flat block in Essex or London, an audio replacement using existing cabling typically falls between £3,000 and £6,000 installed, depending on the cable condition, whether the panel needs repositioning, and the system specified. The installed cost per flat for a video system is higher, reflecting the camera module, video handsets and, where full rewiring is needed, the additional cable and labour cost.
Over a 10-year horizon, the cost difference narrows if a video system reduces the number of security incidents requiring contractor attendance, reduces insurance claims, or contributes to a demonstrably higher satisfaction score from residents. These benefits are real but difficult to quantify precisely before installation, which is why most managing agents present both options to the board with an honest assessment of the incremental cost.
Maintenance costs over the 10 years are broadly similar between audio and video systems from the same manufacturer, assuming both are installed correctly. Video systems have one additional potential failure point in the camera module itself, but modern cameras are sealed units with no moving parts and a reliable service life of 10 years or more in typical UK conditions.
What Residents and Directors Typically Prefer
In blocks surveyed by managing agents, resident preference for video over audio tends to be stronger in urban settings and in blocks that have had previous incidents of tailgating or unauthorised access. In quieter suburban or rural settings, residents often find audio adequate and are more focused on reliability than on additional features.
RMC directors, who are themselves leaseholders, typically prioritise total cost and disruption. A video system that costs significantly more and requires rewiring will usually require a formal presentation to leaseholders with a supporting cost-benefit case. ARMA's guidance on major works consultation sets out the process for presenting significant capital expenditure proposals, including the documentation standards that managing agents are expected to maintain.
The pattern across managed blocks in Essex and Greater London is that audio on existing cabling is the default choice for blocks replacing a working system, while video is more commonly installed during a full refurbishment or in a new development where there is no existing cabling constraint.
Which Is Better for Your Property Type
Audio on existing cabling is the right default for blocks where the existing infrastructure is serviceable, the system is being replaced at end of life rather than as part of a wider refurbishment, and the board has no specific security concern that video would address. It is faster to install, costs less, and delivers a reliable service life of 15 to 20 years from a quality system.
Video makes more sense where the existing cabling is being replaced anyway, where the block is undergoing a broader refurbishment, or where there is a documented security concern that audio alone cannot address. In those cases, the incremental cost of video over audio is relatively modest compared to the total project cost, and the improvement in resident experience is meaningful.
An access control survey of the block is the most reliable starting point: it confirms whether existing cabling can carry video, establishes the current condition of the system, and gives the board an objective basis for choosing between options.
Security Masters installs and maintains audio and video intercom systems in blocks across Essex and London. MLA Approved and fully insured. Call 01277 364666 or email info@security-masters.co.uk to book a site survey.
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