An existing network socket is not proof that its cable can safely supply a new camera, access-control device or Wi-Fi access point. For anyone considering Power over Ethernet in commercial buildings, reusing cabling can be sensible, but the proposed equipment and the complete cable route need assessing together.
The decision is not simply whether data passes. It is whether the cabling, connections, power source and environment suit the planned load. Section 716 in the current Wiring Regulations makes this a timely question, not a reason to replace every old network cable.
What counts as PoE in commercial premises?
Power over Ethernet (PoE) carries data and extra-low-voltage DC power over suitable network cabling. A suitable PoE switch can supply compatible CCTV cameras, access-control devices, wireless access points or purpose-designed lighting.
Not every Ethernet connection carries power. Whether the project involves a holiday park, leisure venue or office, start with a device list showing intended locations and power requirements, rather than assuming every existing outlet can be reused.
What BS 7671 Section 716 means for PoE
BS 7671:2018+A4:2026 was published on 15 April 2026. Its transition period ended on 15 October 2026, when the previous version was withdrawn. It is now the current edition. The IET and BSI announcement of Amendment 4 introduces Section 716 for PoE.
This covers extra-low-voltage DC distribution over information and communications technology (ICT) cabling, including design, installation, verification and use of existing infrastructure.
BS 7671 is a technical standard, not the law itself. Electrical safety duties at work arise separately under the Electricity at Work Regulations 1989. The applicable UK PoE electrical requirements depend on the system and location, so generic voltage or current figures are no substitute for checking the full standard.
Can existing data cabling support the proposed devices?
Sometimes, but neither a cable-category marking nor a successful data connection settles the question. Reusing existing data cabling for PoE needs evidence about the full link, not just the visible socket.
Start with available drawings, test reports and proposed device specifications. Missing records do not automatically rule out reuse, but they affect what needs establishing on site. Build the review into the programme so cable discoveries do not dictate the installation late in the job.
Ask the electrical and network specialists to establish:
- The proposed devices, their power requirements and operating locations.
- Cable type, condition, route and length, including any uncertain sections.
- The suitability of patch leads, outlets, panels and other connections.
- Existing records and any further electrical verification or cabling-performance tests needed.
- Environmental exposure, surrounding temperature and other powered cables sharing the route.
- The switch's per-port capability and total power capacity for the intended devices.
Make reuse a defined part of the scope
Ask for the proposal to identify which links can be reused, what evidence supports that decision and which sections remain unconfirmed. Where access is restricted, agree how further investigation or replacement will be authorised. That avoids an apparently complete price depending on an assumption that every cable behind a finished ceiling is suitable.
During commercial electrical fit-outs, resolve these questions before ceilings are closed or equipment is ordered. The result might be full reuse, selective replacement or new routes; it should follow the findings.
Why location, cable routes and switch capacity matter
A dry office route and a run towards a damp gatehouse or outdoor camera present different conditions. Assess moisture, heat, physical protection and cable grouping along the route, not only conditions at the end device.
Supplying power means cable heating and connection suitability need consideration alongside data performance. A speed test or link light does not establish electrical suitability.
Power-source capacity needs checking at two levels: the individual port and the switch's total available PoE power. Enough spare data ports does not necessarily mean enough power for all planned devices.
Also ask what happens if that switch or its mains supply fails. Several cameras or access devices may share that dependency. Decide which functions need continuity and how an outage will be reported. For access control, the required failure behaviour should be coordinated with the building's wider safety arrangements by the appropriate specialist. PoE is a method of supplying devices, not an assurance that they will keep operating through a supply failure.
Agree who checks the electrical installation and network
The site operator should agree responsibilities before ordering, particularly for commercial PoE CCTV and access control. One contractor's completion record should not be assumed to cover another's scope.
The electrical contractor should define the electrical design and verification within their appointment, including relevant supply arrangements. The IT or structured-cabling provider should address cabling performance, network configuration and security. The device supplier or access-control specialist should confirm equipment compatibility and operating requirements.
An EICR is not network certification
An electrical installation condition report (EICR) does not automatically test or certify the whole data network. Equally, a network performance report is not proof of electrical verification. Record who will resolve gaps and coordinate handover.
Agree the handover evidence before work starts
For a commercial Power over Ethernet installation, specify the records you need in the quotation, not after commissioning. Depending on the agreed scope, request an updated device and port schedule, cable-route information, relevant electrical certification or verification records, and separate cabling test results.
Agree how equipment settings, operating instructions and any resilience arrangements will reach the appropriate site or IT contact. Note untested sections, retained equipment and outstanding actions, with an owner for each.
Include a functional handover of the intended devices with the right specialists present. Seeing one camera image or one working access point is not evidence that every part of the installation has been checked.
Record the accepted device loads and any spare capacity so future changes can be checked against the assessed system. A replacement camera or higher-demand access point should not be treated as interchangeable just because it uses PoE. Keep agreed limitations with the records for the next contractor.
Do existing PoE systems need a blanket upgrade?
No. An installation built to an earlier edition of BS 7671 is not automatically unsafe or due for replacement because Amendment 4 has arrived. Condition, suitability for continued use and proposed alterations matter.
Assess new devices and changed loads on their merits. Where records are incomplete, agree proportionate investigation rather than assuming either that all cabling is satisfactory or that it must all be stripped out. The useful outcome is an evidence-based scope: what can stay, what needs attention and what remains unverified.
To discuss the electrical side of a Power over Ethernet installation in Cornwall, call Maenporth Electrical Ltd on 01326 250297. Our commercial electrical services cover Falmouth, Penryn and the wider county. Have your device list and available cabling records ready.