Power over Ethernet (PoE) – Testing & Installing Devices

power over ethernet colorado springsMany devices, like security cameras, require a separate power source – meaning that more wiring and complexity are needed. However, Power over Ethernet or PoE, is a better way of wiring – the Ethernet cable running to a device can also supply the power needed to run the device. This eliminates many of the problems of traditional CCTV security cameras. Power over Ethernet can also power other automated systems.

To install PoE (Power over Ethernet) systems,  basic electrical principles and rules need to applied. If issues occur during installation, a digital network tester must be used to  to measure and detect Power over Ethernet (PoE) errors.

Power over Ethernet (PoE) options

Two Power over Ethernet (PoE) variances are available. One PoE, referred to as “Standard PoE” ensures that a max of 12.95 watts is present at the device, in this case a security camera. This provides a working voltage of 37 & 57 volts DC.

There is also a higher variant of PoE, often referred to as PoE+.  Power over Ethernet Plus supplies 25.5 watts at a voltage between 42.5 and 57 volts at the device.

PoE Operating Modes & Power Specs

In addition to these two variances, two operating modes are available. Mode A supplies positive power on pins 1 and 2 and negative power on pins 3 and 6, while mode B uses pins 4 and 5 for positive power and pins 7 and 8 for negative power.

Two types of power supply are possible. A midspan injector is connected between the switch and the device. 12.95 watts is the maximum that Midspan can support.

Power Supply – Midspan PoE

Midspan operates in mode B and operates using spare pairs that are not needed for 10Base-TX and 100Base-TX Ethernet.

Power Supply – PoE Routers & Switches

As another option,PoE enabled routers and switches can supply the power. This is compatible with 1000Base-TX Ethernet speeds. Data lines supply the power.

PoE (Power over Ethernet) Problems

A Power over Ethernet device like a security camera can only operate when power is supplied. Therefore, power is supplied when the device is plugged in. The actual power supply is higher than the specs listed. Why? The power must overcome the resistance of the cable itself.  For PoE it is 15.4 watts and PoE+ it’s 30 watts.

4, 7, 15.4 or 30 watts are the max classes that PoE can supply.

A high quality cable is worth using in Power over Ethernet applications.  A poor quality cable will leave insufficient  power for the device, and it will power off. A high quality solid CAT6 cable is best, especially for PoE+, due to its higher current carrying capacity.

Digital Network Testers installing PoE

Need to know the length of a cable, or measure distance? A digital network tester can help!

Installing Power over Ethernet (PoE) requires the use of digital network testers. The availability of PoE, the maximum power available as well as the supply voltage range and power supply mode are displayed on a tester. The digital network tester will also identify which pairs are transmitting the PoE voltage, test the link speed and capability.

Network Testers can also show IPV4 and IPV6 protocols, ping IP and URL addresses and establish whether CDP or LLDP protocols are used. When using the network mapping capabilities, the tester will show MAC addresses, device names and IP addresses, in addition to VLAN identification.

To find errors and faults, link light identification on the tester can identify which port the cable is connected. Plus, a tone generator can even trace, show and identify individual cores.  Open circuits, short circuits and incorrect RJ45 connections can be identified.

How to install Power over Ethernet (PoE)

It can be overwhelming trying to find & install the right Power over Ethernet devices that are just right for you.

Let Wire Works Co Inc help. If you live in Colorado Springs we would be more than happy to be of assistance. With over 20 years of experience you can fully depend on us to provide work of the highest quality and with the most up-to-date techniques. Contact us!


Wire Works Company Incorporated

102 S Tejon Street Suite 1100

Colorado SpringsColorado 80903

United States

Phone: (719) 492-6955

Wire Works Co Inc provides electrical wiring in Colorado Springs, Colorado and the surrounding areas. Give us a call today – our specialized consultations can take your electrical wiringhome automation & security systems to the next level. Our electricians are certified and hold all proper licensing & insurance.


Comments are closed.