Structured Cabling & PoE
Cat5e/6/6a cabling standards, PoE power budgets, and testing requirements per BS EN 50173
Cable Categories and Performance
Structured cabling standards define the performance of copper data cabling by category, each supporting higher bandwidths and data rates.
Common cable categories
ISO/IEC 11801, TIA-568| Category | Max Frequency | Max Data Rate | Max Channel Length |
|---|---|---|---|
| Cat5e | 100 MHz | 1 Gbps | 100 m |
| Cat6 | 250 MHz | 1 Gbps (10 Gbps to 55 m) | 100 m |
| Cat6a | 500 MHz | 10 Gbps | 100 m |
| Cat7 | 600 MHz | 10 Gbps | 100 m |
| Cat8 | 2000 MHz | 25/40 Gbps | 30 m |
Cat7 requires proprietary connectors. Cat8 is typically used for short data-centre links.
Power over Ethernet (PoE) Standards
PoE delivers DC power alongside data over standard Ethernet cables, eliminating the need for separate power supplies at each device.
IEEE PoE standards
IEEE 802.3| Standard | Common Name | Max Power (PSE) | Max Power (PD) | Pairs Used |
|---|---|---|---|---|
| 802.3af | PoE | 15.4W | 12.95W | 2 pairs |
| 802.3at | PoE+ | 30W | 25.5W | 2 pairs |
| 802.3bt Type 3 | PoE++ | 60W | 51W | 4 pairs |
| 802.3bt Type 4 | PoE++ | 100W | 71.3W | 4 pairs |
PSE = Power Sourcing Equipment (switch). PD = Powered Device. Cable losses account for the difference.
Cable Heating with PoE
Cable Testing
All structured cabling should be tested and certified after installation. Verification checks basic continuity and wiring. Certification tests the full frequency performance against the relevant standard (Cat5e, Cat6, Cat6a) and provides a pass/fail result with detailed measurements including insertion loss, NEXT, and return loss.
Certification Pays Off
Separation from Power Cables
BS 7671 Section 528 requires separation between power and data cables to prevent electromagnetic interference. Unscreened data cables require a minimum 50 mm separation from single-phase power cables and 200 mm from three-phase or high-current circuits. Screened cables (FTP/STP) can reduce these distances. Segregated compartments in trunking also satisfy the separation requirements.