Question 1

What is PoE and PoE+ and PoE++?

Accepted Answer

802.3af (PoE) delivers up to 15.4W per port. 802.3at (PoE+) delivers up to 30W — the standard for most enterprise APs and VoIP phones. 802.3bt Type 3 (PoE++) delivers up to 60W and Type 4 delivers up to 90W — required for WiFi 6E tri-radio APs, PTZ cameras, and video conferencing endpoints. Always check your device's PoE class before selecting a switch.

Question 2

How do I calculate the PoE budget I need?

Accepted Answer

Multiply the max wattage of each PoE device by the number of devices, then add 20% headroom. Example: 8 access points at 25W each = 200W + 20% = 240W minimum PoE budget. Many switches advertise 30W per port but limit the total PoE budget to 370W for a 48-port switch — meaning not all ports can run at max wattage simultaneously.

Question 3

Can I mix PoE and non-PoE devices on the same switch?

Accepted Answer

Yes. PoE switches only deliver power to devices that negotiate PoE — a standard PC or server plugged into a PoE port will receive data only, no power. The switch automatically detects whether a connected device is PoE-capable before delivering power, so mixing device types is completely safe.

Question 4

What happens if I exceed the PoE budget on a switch?

Accepted Answer

When total PoE demand exceeds the switch budget, the switch prioritizes ports based on port priority settings (high/medium/low). Lower-priority ports will have power cut, potentially taking APs or cameras offline. Always size your PoE budget with at least 20–30% headroom, and configure port priorities so critical devices (core APs, security cameras) never lose power.

Standard	IEEE Spec	Max Per-Port	Typical Devices	Wires Used
PoE	802.3af	15.4W	VoIP phones, older APs, basic cameras	2 pairs
PoE+	802.3at	30W	WiFi 6 APs, PTZ cameras, VoIP + video	2 pairs
PoE++ Type 3	802.3bt	60W	WiFi 6E dual-radio APs, LED lighting	4 pairs
PoE++ Type 4	802.3bt	90W	WiFi 6E tri-radio APs, digital signage	4 pairs
UPOE (Cisco)	Cisco proprietary	60W	Cisco 8845 phones, Meraki MR57	4 pairs

Device	PoE Standard	Typical Draw	Notes
Enterprise WiFi 6 AP (dual-radio)	PoE+ (802.3at)	18–25W	Most enterprise APs in this range
WiFi 6E AP (tri-radio)	PoE++ (802.3bt)	30–50W	Ubiquiti U6 Enterprise, Meraki MR57
IP Dome Camera (1080p)	PoE (802.3af)	8–12W	Standard fixed cameras
PTZ Camera	PoE+ (802.3at)	15–25W	Higher wattage for pan/tilt motors
VoIP Desk Phone	PoE (802.3af)	3–6W	Low draw, most budget on APs
Video Conferencing Bar	PoE++ (802.3bt)	40–60W	Poly Studio, Logitech Rally Bar

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Common PoE Device Wattage Reference

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