Testing Power over Ethernet
As you prepare to either install new power sourcing equipment (PSE), which could be a PoE enabled switch or mid-span injector or you are working with an existing one, here’s a few things to keep in mind to ensure a smooth deployment.
When provisioning the PSE for the various powered devices (PD) such as VoIP phones, security cameras, Wi-Fi access points and badge scanners to name a few, it is important to calculate the overall power requirement for all devices you are planning to connect to a given PSE to ensure it doesn’t get oversubscribed. The chart below provides you with the level of power that is required at the PD depending on which IEEE standard you are working with.
While it’s ok to test the PoE voltage directly at the PSE, best practice is to test for the wattage or voltage level at the wall jack where the PD plugs in. This is important because PoE will dissipate as it traverses the cable so you want to ensure the power at the wall jack is what is required per PD.
Keep in mind that PoE is subject to the same cable distance limitation as standard Cat 5, which is 100 meters or 328 feet. If the physical cable is out of specification and longer than the TIA standard, power may be too weak by the time it reaches the PD.
Common PoE Issues to watch out for:
- PoE is subject to the same distance limitations as standard network cable runs - 100m/328ft
- Incompatibility between powered device (PD) and power sourcing equipment (PSE)
- Switch over subscribed from a PoE perspective
- Switch provisioning of PoE
- Power limited per port
- Cable faults
Download your own one page reference flyer for PoE standards and PD devices.