Advantages Outweigh Disadvantages

The result of the progress in these areas is an increasing trend among electrical contractors, network designers, lighting contractors, and others to incorporate PoE systems when designing new or retrofit systems for commercial buildings. The advantages and disadvantages of PoE systems include the following characteristics:


  1. No need for ac to dc converters for many powered devices
  2. Elimination of building wiring and wall plugs
  3. Installation does not require a licensed electrician for low-voltage network
  4. Line voltage is typically 50 or 60 V, so safer for working in premises areas, and less risk of overloads damaging the equipment or powered devices
  5. Control of lights and other devices through the Ethernet switch, eliminating the need for wiring a separate wall-plate or other switchControl of lights and other devices through the Ethernet switch
  6. Greater energy efficiency, resulting from the power sources’ power-management software
  7. Cat-5e and Cat-6 cables and 8P8C (eight position eight contact) connectors are mature technologies with the following attributes:
    a.) specifications in well accepted, long-standing standards, for network design and installation methods
    b.) widespread availability from well-established manufacturers and distributors
    c.) excellent product uniformity
    d.) strong familiarity among network designers and installers
  8. Reliability – Ethernet network equipment often is backed up with uninterruptible power supplies
  9. Flexibility in locating powered devices, such as cameras, and in repositioning them, because there is no need to be near a wall-plug or power cable
  10. No need for expensive equipment – four- or eight-port Ethernet switches can fall in a range of US$100 to US$300



  1. Heat dissipation, which limits the number of cables bundled in a cable tray or plenum area
  2. Safety risks due to excess heat buildup
  3. Degradation of performance – data or power transmission – due to heat buildup
  4. Distance limitations
  5. Failure risks associated with having multiple devices may be powered by a single multi-port Ethernet switch
  6. Connector performance if arcing has occurred during un-mating and caused pitting on the connector contacts. (Note, this depends on the current levels and location of the pitting.)