The energy consumed per unit by a switch is an important factor for a buyer to know. Power used by a switch differs not only based on its type and configuration but also on the IEEE standard for power consumption. This standard is different for PoE, PoE+, and PoE++. This power ranges from 12.95 W to 90 W. The consumption depends on the device which receives the power, such as computer, camera, IP phone, lights and more. It also depends on the number of connected devices to one PoE switch. Devices such as video conferencing equipment, laptops, and relatively more powerful equipment would require more wattage such as 60 W or 100 W.
What Affects the Power Consumption of PoE Switches?
Here are some factors that affect a PoE switchs power consumption.
- Number of ports: The number of ports in a network switch may range from 2 to 48 and beyond. Out of the total number of ports, only a quarter of them would be PoE enabled for most models. But on newer model PoE switches for example those made by Luminetworx for primary use in PoE Lighting and Building Automation installations all avaialble ports are PoE capable. The rest of the ports are usually standard networking or SFP ports for Ethernet cable connectors and fiber optics without PoE functionality. The wattage capability PoE in switches is dependant on the size of the power supply in the PoE switch itself.
- Number of connected devices: The number and type of connected devices certainly impacts the power consumption of a switch. The wattage is distributed over the number of ports. So, if the switch budget is 15.4 W and there are 3 ports, all the ports would not be able to supply the same amount of power over a cable. Also, the requirement of each device would be different. For instance, a camera may require less power than a computer.
- Type of switch and its wattage: There are industrial PoE switches which are designed for harsh operating environments. Such switches are managed and easily use around 500W power. Unmanaged switches with basic configurations use less power around 50-60W in total for all the ports. So, this largely depends on your application requirement and the type of switch you choose, such as PoE, PoE+, and so on.
Will PoE Switch Consume More Electricity?
No, in fact PoE switches help save electricity. A PoE switch may seem more expensive than normal switches; however, it is cost effective in the long run because of the energy efficiency in power conversion. For example lets discuss PoE Lighting, a standard high voltage LED light converts 110VAC to 12-24VDC in order to power the LED. This is done through the use of an LED driver. The problem with most high power LED drivers is that they are not very efficient most are only about 65-75% efficient in converting power from high to low voltage. That loss in efficiency costs you the home owner, property owner management company every time you pay your electric bill. But a PoE switch is 95% efficient and getting more efficient every day. That efficiency in power conversion is key to energy savings. It also saves when installing the required infrastructure and wiring for the building.
It is absolutely essential to save energy and hence the use of energy-efficient devices in your infrastructure. Using energy-efficient PoE switches will help restore available energy as most devices may require less energy than their maximum limit. PoE technology as a whole is a great option for data networks, whether Ethernet, fiber optic, or blended, to save on external energy resources and the concerned infrastructure. With the addition of PoE Lighting and other poE devices like Monitors, computers, IOT sensors and more property owners and developers are able to capitalze on capital expediture savings as well as long term energy useage. However, it is essential to choose the right PoE switch that is compatible in every way for the intended use.
Is PoE Safe? Why PoE Is Safe
Most people already interact with PoE every day, whether they’re connecting a VoIP phone to the wall or using a display in a meeting room.
Because of the way it works, PoE is built to be inherently safe:
- A PoE switch combines and separates data and power.
- The power sourcing equipment (PSE) that provides power on the cable (like a PoE switch) must experience a “handshake” with the PD (powered device or endpoint device) before any power is delivered. This handshake determines how much power the PD needs.
- If there is no PD connected or no handshake between the PD and PSE, then no power is delivered. There needs to be a connection first.
- Once the connection is established, the PSE constantly monitors the amount of current being sent. If the current goes too high or too low, the PSE immediately shuts down the flow of power.
This is much different than how an AC power receptacle on your wall works. There, power is being supplied 24/7, regardless of whether a device is connected (which is how electrical shock occurs).
The real question isn’t “Is PoE safe?” Instead, it’s “How much power can safely be delivered from the PSE to the PD?” That answer depends on the temperature rise in the center of a cable bundle. Since power over ethernet is trasmitted over the multiple cables in a Cat 6 cable it allows for higher voltages to be transmitted using smaller guage wire as in cat6 cable when compared to high voltage installations. Then we have to take SKIN EFFECT into consideration. But what is skin effect? In high voltage electricity, the tendency of alternating high-frequency currents to crowd toward the surface of a conducting material. This phenomenon restricts the current to a small part of the total cross-sectional area and so has the effect of increasing the resistance of the conductor ( the energy in AC current flows on the outer surface of the conductor and does not use the core of the conductor to transmit power). DC volatge or what is use by PoE does not suffer from SKIN EFFECT and therefore is able to use the entire conductor aloowing for smaller diameter conductor to be used to transmit higher volatages.