Guide
PoE – is there enough power?
PoE lets access points, cameras and phones get power over the network cable. But every port has a maximum and the whole switch a total budget that depends on the power supply. Here is how to calculate.
Short answer
Check two things: that each port delivers enough (PoE+ 30 W, UPOE 60 W, UPOE+ 90 W) and that the total PoE budget covers everything powered. Add up the power, add a 20–30 percent margin and compare with the data sheet. If it falls short, use a second power supply, another switch or a PoE injector.
Which PoE standard do you need?
The power per port is set by the switch port type (P, U or H in the part number).
- PoE (802.3af) – up to 15.4 W per port: phones, simple cameras
- PoE+ (802.3at) – up to 30 W: most Wi-Fi 6 access points and cameras
- UPOE / 802.3bt type 3 – up to 60 W: Wi-Fi 6E/7 access points, PTZ cameras
- UPOE+ / 802.3bt type 4 – up to 90 W: thin clients, lighting, displays
How large is the total budget?
On the Catalyst 9300 the power supply decides how much PoE the switch can deliver in total. A second power supply gives redundancy and can raise the budget. Add up everything that needs power and add a 20–30 percent margin.
Read more: Which switch suits the office?
What if the switch is not enough?
If the switch port has no PoE, or not enough, a single access point can be powered by a PoE injector between the switch and the access point. The AIR-PWRINJ6 delivers up to 30 W (PoE+); Wi-Fi 6E/7 access points that need more require an 802.3bt multigigabit injector.
Read more: Which access point?
Conclusion
How we would choose
Examples:
Catalyst 9300 48-port UPOE (Network Essentials)
48 UPOE ports (60 W) for Wi-Fi 6E/7 and cameras.
715W AC 80+ platinum Config 1 Power Supply
Additional power supply for the Catalyst 9300 – redundancy and more PoE.
Power Injector (802.3at) for Aironet Access Points
PoE+ injector (30 W) for an access point on a port without PoE.
Frequently asked questions
Questions we often get
How much PoE does an access point draw?
Wi-Fi 6 access points usually fit within PoE+ (30 W). Several Wi-Fi 6E and Wi-Fi 7 models need 802.3bt (UPOE) for full functionality. The power is in the access point's data sheet, which we link on the product page.
Do two power supplies give more PoE?
On switches with room for two power supplies, e.g. the Catalyst 9300 and most 9200L models, the second supply can both add redundancy and raise the total PoE budget. The data sheet shows how much.
What happens if the budget runs out?
The switch cannot power more devices than the budget allows, so the last devices do not start. PoE priority lets you control which ports get power first. That is why we always plan with a margin.