Michiel Panders, R&M general manager, Europe looks at PoE implementation.

New PoE-compatible devices are being introduced almost every day. These include devices for LAN, as well as for industrial and building automation applications. Whereas the original PoE standard supported 12.95 watts, but the latest version can deliver up to 90W on every PoE port – and this has significant consequences for cabling as temperatures can rise considerably. The greater the power level supplied, the more heat is generated - which in turn affects data transfer. New legislation and standardization will have a major impact on cabling and failure to comply introduces several issues, from poor system performance to questions from insurance companies...

Remote power category RP3 is now mandatory in newly built systems for offices, homes, and industries, and in Smart Building systems. Each cable in a bundle must be able to fully support PoE at the highest level. Assurance that the cable bundle will not overheat is essential for achieving category RP3 compliance.

In short: right now is a good time to reflect on these matters. To ensure long-term reliable operation of networks, the ISO/IEC 14763-2 and EN 50174-2 standards for cabling have been extended to include Remote Power supply categories RP1, RP2 and RP3. According to ISO/IEC 14763-2, a 'Remote Power' category must be specified for each installation. Planning, installation, and product selection must support the specified category. These three new categories define requirements prior to installation and after commissioning to keep cabling and PoE running safely. The RP category is determined by the average allowable DC current in a cable bundle - the higher the rating, the higher the permissible current.

The standard requires warning labels to be affixed to RP1 and RP2 installations. Before connecting a PoE device, it is vital to check whether the maximum permissible current can be supported - and that can be time-consuming. With RP3, cabling is configured during the planning phase, so that all cables can transmit the maximum PoE current at the same time. This makes the system particularly safe.

Network planners must ensure the attenuation budget for data transmission can always be respected with RP3 cabling and that the permissible temperature in the cable is not exceeded. This can be achieved in part by adjusting link lengths to the installation.

By planning in the appropriate way and choosing suitable products, your cabling system meets the high requirements of the latest PoE standard. One of the most important measures is planning shorter connections for your LAN. The shorter the cable connection, the less resistance, heating, and damping losses occur during data transmission.

Differences in resistance between cables in the bundle may increase the effective current value and can therefore invalidate RP3 certification. In LAN cabling, we often see differences in resistance between the cables in cable pairs, which can negatively affect PoE. Fortunately, test equipment manufacturers are making it possible to go beyond basic requirements described in standards such as ISO/IEC 11801. Various devices now offer options to test for additional parameters. Thermal stress can only be managed if this resistance imbalance is kept to a minimum.

Now that PoE is being used more widely, real-world testing is more important than ever. This ensures installations can continue to support PoE avoiding issues with, for example, disrupted data transfer or failure due to excess heat. Complying with the new 'Remote Power' categories is, therefore, of great importance for fulfilling warranties and preventing expensive, time-consuming equipment replacements and repairs.