Smart Buildings

Unleashing the Potential of POLAN: Remote Power Strategies

Ron Tellas and Michael Bodzay
Remote power options, including Class 2, PoE and Class 4, make POLANs a viable option when fiber is being used, untethering them from traditional power limitations.


As smart buildings continue to deploy more devices and technology, remote power is becoming more common—and more critical. It can supply all the necessary power for your network (including end devices) from one location.


With new technology advancements that increase available power and allow safe, efficient and widespread use of direct current (DC), installation of devices and equipment is no longer limited by the location of an AC outlet. Instead, devices can be placed wherever they’re needed—whether that means on top of a streetlight, in a parking lot, across a stadium or on a rooftop.


Remote power is also making passive optical LANs (POLANs) a more viable option in environments where fiber is already being used. It untethers these networks from traditional power limitations and enables the connection of endpoints that are sometimes miles away.


As an alternative to a traditional LAN network, an optical LAN is a point-to-multipoint network that relies on FTTx architecture and protocols instead of switch-based Ethernet. In other words, it relies on singlemode fiber, passive optical splitters, optical line terminals (OLTs) and optical network terminals (ONTs) rather than Ethernet cables, routers and switches.


Within a POLAN, power is necessary to support:

  1. The MDF (main distribution frame): the central point connecting the network to the outside service provider.

  2. The IDF (intermediate distribution frame) or TR (telecommunications room): the many areas throughout a building that provide endpoint device access to the MDF.

  3. Endpoint connectivity: the devices that must connect to the network.


3 Remote Power Options to Consider for Optical LANs

To extract the most value from an optical LAN, the right power solution is required. There are several options to consider.


Direct Current/Class 2 Systems

As defined in the National Electrical Code (NEC) as Class 2, DC carries 100W and has a “practical” reach of around 250 m.


Low-voltage Class 2 systems provide remote DC power to connected devices. For safety and fire prevention, the NEC specifies maximum power output and voltage levels for Class 2 circuits.


Class 2 systems convert AC to DC power using an AC-DC rectifier from a centralized source. From there, power enters a current-limiting DC-DC converter that turns 48V DC into a Class 2 power source. Copper wires (Category cabling or hybrid fiber cabling) carry power to end devices, such as optical network terminals (ONTs) in optical LANs. As a result, Class 2 systems can be installed by the same systems integrators that install fiber and Category cabling.


Based on the application, remote powering systems that support optical LANs can be designed as:

  • Distributed systems, where energy is produced closer to where it’s needed.
  • Centralized systems, where power is generated at a central location and transported to wherever it’s needed.


Power over Ethernet Systems

Also defined as Class 2, Power over Ethernet (PoE) carries 100W and has a “practical” reach of up to 215 m (Ethernet itself is limited to 100 m).


Power over Ethernet (PoE) allows data and power to be transmitted to devices using just one cable, which reduces costs and simplifies installation by eliminating the need for separate power cables.


PoE has been through many iterations. The first PoE standard, IEEE 802.3af, was ratified in 2003 and supported 15.4W. Today, IEEE 802.3bt is the newest standard. It calls for two PoE variants: Type 3 (60W) and Type 4 (100W). This enables more electricity to be carried over a single cable to devices that have more power needs, such as IP cameras, wireless access points, LED fixtures and large displays.


Class 4 /Fault-Managed Power Systems

Class 4 systems, also known as fault-managed power (FMP) systems, were included in the NEC for the first time in 2023.


This new classification standard safely brings FMP technology—which also includes packet energy transfer (PET), Digital Electricity™ (DE), pulsed power and smart transfer systems—into the NEC.


Class 4 circuits provide the safety and convenience of PoE but can offer close to 20 times the power of PoE across hundreds or thousands of meters, offering a safe alternative to AC power.


To ensure safety, these systems limit energy and power available during a fault event. To limit fault energy, a transmitter and receiver monitor for faults and control power delivery. If someone touches exposed wires or splashes water onto circuits during operation, then the system automatically and immediately shuts off. This makes Class 4 systems just as safe as—if not safer than—Class 2 systems while offering more power availability.


Like Class 2, Class 4 power can be delivered through technology that unites power and data in a single cable run.


Making the Right Power Choice for POLAN

How do you know which option—Class 2, Power over Ethernet or Class 4—is right for your POLAN application? That question can be answered by considering what we call the 3Ds: data, distance and delivery.

  • Data: What is the data rate?
  • Distance: How far from the network connection is it?
  • Delivery: How much power needs to be delivered?


Understanding the 3Ds that make up your environment will help you make the right choice. If you still have questions, however, Belden is always here to help. You can also see some examples of how we power optical LANs in our Remote Powering of Your Optical LAN use case flyer.


We want to thank Tellabs for helping us with this blog. Both organizations see the benefits of POLAN in the right applications and are active members of APOLAN and HTNG (Hospitality Technology Next Generation).


We’re working on a series of POLAN blogs together, covering topics like:


Make sure you don’t miss the information we’ll continue to share about optical LANs! 



Related resources: