Active PoE vs. Passive PoE: Which Should You Use?


Power over Ethernet (PoE) is a solution that provides data transmission and electric power to devices using one cable. That means that end-users can power PoE capable devices without separate power supplies or electrical outlets near the powered device.

There are different types of PoE technology. Some PoE just provides active PoE and others provide passive. If you want to know more about the difference between active PoE and passive PoE, you can read this article.

What Is Active PoE?

Active PoE works according to a set standard specification: IEEE802.3af, IEEE802.3at, IEEE802.3bt. These are highly compatible standards. The compliant devices will complete a “power handshaking” with the PoE power supply at low power. If the power handshaking is successful, the device will negotiate the power needed and power up fully. If the handshake fails, the power supply will not deliver any power and the device will not turn on. 

What Is an Active PoE Switch?

The standard/active POE switch is a PoE control chip that is built-in. It will send power to a powered device, then wait for stable transmission. If the device is disconnected, the POE switch will stop supplying power and try to detect it again.
Another similar product is the standard/active PoE injector. The PoE injector doesn't provide switching function. It simply injects the power to the Ethernet cable and sends it together with data to the edge device. It is a handy tool to turn non-PoE switch or routers into PoE compatible equipment.

It is safe for standard PoE switch to work with non-PoE devices such as PC computers because of the power handshaking. The POE switch will only send the data without power when the non-PoE device is attached to the standard PoE switch.

What Is Passive PoE?

Passive Power Over Ethernet, or passive POE, is a type of power input to Ethernet cable that does not require power handshaking. It’s very important to understand the specifications of your device and make sure it requires the same type of POE as the input you are going to provide. For example, many CCTV cameras are passive POE but they need a 12v power supply using either a DC power balun or passive POE injector. However, there are more expensive POE cameras that have an active POE handshake and will negotiate with the switch for the correct input. The same can be said for PoE access points, which require a passive 24v power supply.
What Is Passive PoE Switch?

Non-standard/ Passive POE switches come with safety hazards. They don’t come with a POE control chip, so they can’t tell the difference between PoE cameras and other devices. This can result in transient voltages and may burn out any device connected to it. The price of non-standard PoE switches is cheaper, but you risk sending too much voltage to your devices. Please be aware that passive non-standard PoE switches deliver power without negotiation. If you aren’t sure how to install one of these, we recommend considering a standard PoE switch with active PoE control to prevent the potential hazards. All of the recommendations below are based on a standard PoE switch.

Active PoE Switch vs Passive PoE Switch: The Key Differences

Passive PoE switches deliver power over Ethernet cables, but they don’t comply with any IEEE standard. Active PoE switches, on the other hand, are compliant with IEEE standards, and there is a difference in the power supply pins of these two types of PoE switches. If safety is your top priority, you should use an active PoE switch; if you have a limited budget and cost is your main concern, a passive one might be a better choice.

Security camera systems: Active PoE Switch vs Passive PoE Switch

Active PoE: In this case, IP cameras will not turn on unless it completes a handshake between the PoE power supply and the device. If the handshake isn't approved, then the camera won't turn on.
Passive PoE: When using passive PoE, the camera will turn on regardless of its power parameters. Since there's no power handshaking, you may risk burning out the camera if it's receiving a higher voltage than it can handle.

Cost: Active PoE Switch vs Passive PoE Switch

The cost of an active PoE switch differs from the passive PoE switch mainly because the active PoE switch has a built-in power controller, which the passive one does not. This means that the passive PoE switch relies on information from outside sources to detect and classify the PD (power demand) system. As a result, it’s not surprising that the active PoE switch costs more than the passive PoE switch.

Active PoE Switch vs Passive PoE Switch: Which is the Better Choice for Your Network?

One way to keep your network safe is by using a PoE switch. We suggest active PoE switches because they can detect power wiring issues and help prevent accidents. We may also use passive PoE switches if cost is a concern, but be aware that they do not have any power detection function. It is important to make sure the passive PoE switch you buy matches the power specifications exactly to the device you are powering on, otherwise you can easily damage your device. Finally, it’s never okay to connect computers and other non-PoE devices to the passive PoE switch. Read Everything you need to know about Power over Ethernet to dive into the PoE technology. 
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