BS 7671 Amendment 4: PoE in Schools and Universities

Schools and universities have rapidly adopted PoE for wireless access points, interactive displays, VoIP telephony, and IP CCTV. The DfE Building Bulletin BB103 guidelines for ICT infrastructure in schools assume pervasive Wi-Fi coverage, which translates to a PoE access point every 15-20 metres across the building. Section 716 in Amendment 4 now requires that the heating effect of these PoE installations is accounted for in the electrical design.

The typical education building has a relatively modest structured cabling installation compared to commercial offices — perhaps 6-12 data points per classroom plus backbone cabling. However, the proportion of PoE-active ports is often very high. Where an office might have 30% of data ports carrying PoE, a school with one access point, one IP phone, and one PoE display per classroom could have 50% or more of ports active with PoE.

Ceiling void installations are the primary concern. Wireless access points are typically mounted at ceiling level with Cat 6A cables routed through ceiling voids. In schools, these voids are often shallow and poorly ventilated, with limited space for containment. Section 716 derating factors for enclosed, unventilated spaces are more severe than for open cable trays, which can push cable sizing requirements up significantly.

Multi-academy trusts and local authorities commissioning new school builds should ensure that MEP specifications reference Section 716 from Amendment 4. The containment design must account for PoE heating, particularly in main risers and horizontal distribution routes where cables converge. This may mean specifying wider cable trays or providing ventilation openings in enclosed containment.

Summer temperature peaks are particularly relevant for schools. Section 716 derating factors are applied on top of ambient temperature corrections. In a south-facing classroom with ceiling void temperatures reaching 40°C in summer, the combined derating from ambient temperature and PoE heating can reduce cable capacity substantially. This is the scenario where underspecified PoE installations are most likely to experience cable overheating.

ECalPro's Cable Size Calculator combines Section 716 PoE derating with ambient temperature corrections, providing accurate cable sizing for the specific conditions found in education buildings.