How to Choose a PoE Switch for Access Points and IP Cameras

Q: Can I Connect an 802.3af PoE Device to a PoE+ Switch?

Yes. IEEE 802.3at PoE+ is backward compatible with 802.3af devices, subject to the switch’s total power budget.

Q: Why Does a PoE Camera Disconnect at Night?

Its power demand may rise when IR illumination or a heater turns on. Check the budget, port limit, cable, and device logs.

Q: Can I Connect a Non-PoE Device to a PoE Switch?

Yes, with standards-based IEEE PoE, which detects compatible devices before supplying power. Passive PoE requires a separate compatibility check.

Q: Can I Mix Switches, Cameras, and APs from Different Brands?

Yes, when the power standards and Ethernet interfaces match. Some management features may remain vendor-specific.

Dmitrijs KrivulinsHead of RMA at Getic

Published: October 28, 2026Updated: October 28, 2026

An IP camera works during the day but starts rebooting at night. Or several access points are installed, and some devices begin disconnecting. One possible cause is an insufficient PoE power budget.

Choosing a PoE switch is not just about the number of ports. You also need to check the PoE standard, the power requirements of connected devices, the total available budget, and network bandwidth.

UniFi PoE switch with connected Ethernet cables

Key Takeaways

The number of PoE ports and the total power budget are different specifications.
PoE, PoE+, and PoE++ support different power levels.
Calculate the budget using the devices’ maximum power draw, not just their typical load.
Power headroom and sensible load distribution help prevent outages and make expansion easier.

How Power over Ethernet works
PoE vs PoE+ vs PoE++
Calculating the PoE power budget
Choosing the right switch
Checks before installation
Metrics after deployment
When PoE helps — and when it does not
FAQ

How Does Power over Ethernet Work?

Power over Ethernet (PoE) carries both data and electrical power through a single Ethernet cable.

For example, a ceiling-mounted access point or an IP camera does not necessarily need a nearby wall socket. If it supports a compatible PoE standard, it can receive power directly from a switch.

There are two common ways to provide that power:

PoE switch — supplies data and power through designated Ethernet ports.
PoE injector — adds power to an Ethernet connection for a single device.

For one camera, a compatible PoE injector may be sufficient. With several devices, a PoE switch is usually easier to deploy and manage.

What Is the Difference Between PoE, PoE+, and PoE++?

The main difference is the amount of power available to a connected device.

Standard	Power at the source port	Typical use
PoE (802.3af)	Up to 15.4 W	IP phones, basic cameras, low-power APs
PoE+ (802.3at)	Up to 30 W	More capable APs and cameras with extra functions
PoE++ (802.3bt)	Up to 60 or 90 W, depending on type	High-power APs, certain PTZ cameras, and other demanding devices

These figures describe the power available at the sourcing port. The device itself may receive less because of cable losses.

Important: Passive PoE is not the same as standards-based IEEE PoE. With passive power, check the voltage, pinout, and device compatibility separately.

UniFi Switch Lite 8 PoE with four PoE+ ports

How Do You Calculate the PoE Power Budget?

Suppose a small office needs to power:

3 access points rated at 15 W each
3 IP cameras rated at 12 W each

3 × 15 W + 3 × 12 W = 81 W

With 25% headroom, the required total PoE budget is approximately 102 W.

This is an illustrative calculation, not the actual consumption of a specific product. In a real installation, use the maximum power draw listed in each device’s documentation.

Why leave headroom? Some cameras draw more power when their IR illumination, heater, or motorised mechanisms turn on. A camera that runs reliably during the day can therefore encounter power problems at night.

Always check two separate limits: the maximum power available per PoE port and the total PoE budget of the switch.

UniFi Flex 2.5G 8 PoE — available power budget depends on the power source

Which PoE Switch Should You Choose?

Choose by the number of powered devices, their peak demand, and the required uplink speed. These three Getic models cover different installation sizes.

UniFi Switch Lite 8 PoE: Small Installations

Ubiquiti USW-Lite-8-PoE has eight 1 GbE ports, four with PoE+, and a total PoE budget of 52 W. It suits small setups when the devices’ combined maximum draw stays within that limit.

UniFi Switch Flex 2.5G 8 PoE: Faster Ports and PoE++

Ubiquiti USW-Flex-2.5G-8-PoE has eight 2.5 GbE PoE++ ports and 10 GbE uplinks. With a compatible external 210 W adapter, its PoE budget reaches 196 W; when powered via PoE, it drops to 16–76 W depending on the input standard.

MikroTik CRS328-24P-4S+RM: Larger Networks

MikroTik CRS328-24P-4S+RM offers 24 Gigabit PoE ports and four 10G SFP+ uplinks. Its 450 W PoE budget is divided into three 150 W groups of eight ports, so loads must be distributed accordingly.

Quick Comparison

Feature	UniFi Lite 8 PoE	UniFi Flex 2.5G 8 PoE	MikroTik CRS328
PoE ports	4	8	24
PoE standard	PoE+	PoE++	PoE+
Total PoE budget	52 W	Up to 196 W	450 W
Ports / uplinks	1 GbE	2.5 GbE / 10 GbE	1 GbE / 10G SFP+

Flex 2.5G: 196 W requires the external 210 W adapter. CRS328: maximum 150 W per eight-port group.

What Should You Check Before Installation?

Power draw: Add up the maximum wattages in the devices’ specifications, not their typical use.

Compatibility: Confirm the required IEEE PoE standard and per-port power limit; check Passive PoE separately.

Cabling: Check cable quality, terminations, and length; 100 m is the usual copper Ethernet channel limit.

Uplink capacity: Allow for combined camera streams and access-point traffic.

Expansion: Leave spare ports and power budget for additional devices.

Which Metrics Should You Check After Deployment?

Confirm the switch can support the actual load, not just power devices on:

PoE consumption and remaining budget: Identify ports or groups nearing their power limits.

Port errors: Spot potential cable and connection faults.

Uplink utilisation: Check for congestion under normal traffic.

Device uptime: Find unexpected camera or access-point restarts.

For IP cameras, repeat the checks at night when IR illumination or other features may increase power demand.

When PoE Helps — and When It Does Not

When it helps: Powering cameras and access points where running separate electrical cables is inconvenient.

When it does not: A higher-power switch cannot fix weak Wi-Fi coverage, damaged Ethernet cables, or insufficient uplink bandwidth.

Conclusion

Select a PoE switch by standards compatibility, power per port, total power budget, and available ports. Then check uplink speed and leave headroom for growth. The right choice is the one that meets the actual load—not simply the model with the most ports.