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UniFi PoE Budget Planning for Cameras, APs, and Access Control
UniFi PoE budget planning is one of the most overlooked steps in commercial surveillance design — and PoE budget failures are one of the most common causes of post-installation problems in commercial UniFi deployments. A camera that won’t power on, an access point that reboots under load, or a door reader that drops offline during peak hours — all trace back to under-specified PoE infrastructure. This guide gives network engineers and facilities IT teams the tools to size PoE correctly before installation day.
1. PoE Standards Explained
Power over Ethernet delivers DC power to devices through standard Ethernet cabling. Three IEEE standards govern how much power is available per port:
| Standard | IEEE | Max Power at PSE (switch) | Max Power at PD (device) | Common Uses |
|---|---|---|---|---|
| PoE | 802.3af | 15.4 W | 12.95 W | Low-power cameras, VoIP phones, access readers |
| PoE+ | 802.3at | 30 W | 25.5 W | PTZ cameras, AI cameras, most Wi-Fi APs |
| PoE++ | 802.3bt Type 3 | 60 W | 51 W | High-power APs, PoE lighting, pan-tilt systems |
| PoE++ (4-pair) | 802.3bt Type 4 | 100 W | 71.3 W | Industrial devices, high-power APs, PTZ with heaters |
Critical distinction: The switch port budgets power at the PSE (Power Sourcing Equipment) level. The device receives less power due to cable resistance loss. A 30 W port delivers only ~25.5 W to the device. Budget calculations should use PSE values, and device specifications quote PD (Powered Device) power — verify which value Ubiquiti’s specs reference before planning.
Standards reference: IEEE 802.3at (PoE+) standard | UniFi switch specifications — ui.com
2. UniFi Device Power Draws (at PSE)
Use these values when calculating total PoE budget requirements. Values represent maximum power draw (worst-case planning):
Cameras
| Camera Model | PoE Standard | Max Power Draw |
|---|---|---|
| G5 Bullet (UVC-G5-Bullet) | 802.3af | 4 W |
| G5 Dome (UVC-G5-Dome) | 802.3af | 5 W |
| G6 Turret (UVC-G6-Turret) | 802.3af | 12.5 W |
| AI Turret (UVC-AI-Turret) | 802.3at (PoE+) | 20 W |
| AI Pro (UVC-AI-Pro) | 802.3af (PoE) | 11 W |
| AI Pro (UVC-AI-Pro) – with Enhancer | 802.3at (PoE+) | 22 W |
| G5 PTZ (UVC-G5-PTZ) | 802.3at (PoE+) | 14 W |
| G6 PTZ (UVC-G6-PTZ) | 802.3at (PoE+) | 24.5 W |
Access Points & Access Control
| Device Type | PoE Standard | Typical Max Draw |
|---|---|---|
| UniFi U7 Pro (Wi-Fi 7 AP) | 802.3at (PoE+) | 21 W |
| UniFi U6 Pro (Wi-Fi 6 AP) | 802.3af (PoE) | 13 W |
| UniFi Access Door Hub | 802.3bt (PoE++) | 30–50 W |
| UniFi Access G3 Reader | 802.3af (PoE) | 5 W |
3. UniFi Switch PoE Budgets
UniFi PoE budget planning requires knowing exactly how much each switch model can deliver — the table below is the foundation of every commercial PoE architecture design.
| Switch Model | PoE Ports | PoE Standard | Total PoE Budget |
|---|---|---|---|
| USW-Enterprise-8-PoE | 8 | PoE+ (802.3at) | 120 W |
| USW-Enterprise-24-PoE | 24 | PoE+ (802.3at) | 400 W |
| USW-Enterprise-48-PoE | 48 | PoE+ (802.3at) | 720 W |
| USW-Pro-8-PoE | 8 | PoE++ (802.3bt) | 120 W |
| USW-Pro-24-PoE | 24 | PoE++ (802.3bt) | 400 W |
| USW-Pro-48-PoE | 48 | PoE++ (802.3bt) | 600 W |
Note: The USW-Pro-48-PoE shares 185 W across 48 ports — approximately 3.85 W average per port. In mixed deployments with PoE+ devices, the budget is exhausted well before all 48 ports are used. Always calculate per-deployment, not per-port.
4. PoE Budget Calculation Method
The UniFi PoE budget planning calculation method below eliminates guesswork and prevents the brownout failures that plague under-designed commercial deployments.
Follow this method for every commercial deployment:
- List all PoE devices — cameras, APs, access readers, access hubs, VoIP phones, doorbells
- Record max power draw per device — use the values from this guide or Ubiquiti’s techspecs page
- Calculate total maximum draw: sum of all device max powers
- Apply a 20% safety margin: total max draw ÷ 0.80 = minimum switch PoE budget required
- Select a switch whose PoE budget exceeds this number — with room for planned future additions
- Verify per-port standard: ensure PoE+ devices connect to PoE+ ports; PoE-only switches cannot power PoE+ devices
5. Real-World Planning Examples
Example A — Warehouse Perimeter (20 cameras)
Devices:
- 16× G5 Bullet cameras @ 4 W = 64 W
- 4× AI Turret cameras @ 20 W = 80 W
Total max draw: 144 W
With 20% safety margin: 144 ÷ 0.80 = 180 W minimum switch budget needed
Recommendation: USW-Pro-24-PoE (400 W budget) — just sufficient.
Example B — Office Building (cameras + APs + access control)
Devices:
- 12× G5 Dome cameras @ 5 W = 60 W
- 6× AI Turret cameras @ 20 W = 120 W
- 8× U6 Pro APs @ 13 W = 104 W
- 10× Access G3 Readers @ 5 W = 50 W
- 5× Access Door Hubs @ 50 W = 250 W
Total max draw: 584 W
With 20% margin: 584 ÷ 0.80 = 730 W minimum
Recommendation: Two switches — USW-Pro-48-PoE (600 W each) across two IDF closets, or a single unit with load balancing. Do NOT attempt to run this on a single lower-budget switch.
6. IDF/MDF PoE Planning
UniFi PoE budget planning extends to every IDF closet in a multi-floor facility — not just the total building load.
Commercial buildings distribute network infrastructure across MDF (Main Distribution Frame) and IDF (Intermediate Distribution Frame) closets per floor or zone. PoE planning must account for this topology:
- Size each IDF switch independently — calculate PoE budget for devices connected to each IDF switch, not the total building
- Fiber uplinks between IDF and MDF carry data only, not PoE — devices receive power from their local IDF switch
- Avoid over-subscribing single IDF switches — plan to split devices across multiple switches if a single floor exceeds 70% of one switch’s PoE budget
- AC power to IDF closets — each IDF switch requires local AC power. Verify electrical capacity in each closet, especially in older commercial buildings where closets may have limited circuits
7. Avoiding Brownout Failures
A PoE brownout occurs when total device power draw approaches or exceeds the switch’s PoE budget. Symptoms include cameras randomly dropping offline, APs resetting under high client load (when radio power draw peaks), and access readers intermittently failing to unlock doors.
Prevention strategies used by 2M Technology on every commercial deployment:
- Never exceed 80% of total PoE budget: leave 20% headroom for startup surges and planned additions
- Use UniFi’s PoE monitoring: UniFi Network Controller shows per-port and total PoE consumption in real time — review after installation and quarterly
- Stagger PoE device startup: after a power outage, simultaneous restart of all cameras can surge past the switch budget momentarily — UniFi switches handle this with PoE port priority settings
- Set PoE port priority in UniFi: assign access control readers and critical cameras higher PoE priority than overview cameras — ensures critical devices power on first if budget is approached
8. Long Runs & Power Loss
PoE power delivery efficiency decreases with cable length and cable quality:
- Maximum run length: 100 meters (328 ft) per IEEE 802.3 specification for both data and PoE
- Cat5e vs. Cat6: Cat6’s lower resistance provides better power delivery efficiency on long runs — use Cat6 for all runs exceeding 60 meters and all PoE+ devices
- Avoid splitters and couplers: Ethernet couplers, inline splitters, and low-quality patch cables introduce resistance that reduces available power at the device end
- PoE extenders: For runs beyond 100 meters, UniFi and third-party PoE extenders repeat both data and power — useful for distant parking lot cameras or fence line coverage without additional IDF infrastructure
UniFi PoE Budget Planning — Switch Selection Quick Reference
| Total Max Device Load | 20% Safety Margin Applied | Min Switch PoE Budget | Recommended UniFi Switch |
|---|---|---|---|
| Under 80W | 100W | 100W+ | USW-Enterprise-8-PoE (120W) |
| 80–150W | 188W | 190W+ | USW-Pro-24-PoE (400W) — borderline; prefer Enterprise |
| 150–320W | 400W | 400W+ | USW-Enterprise-24-PoE (400W) |
| 320–480W | 600W | 600W+ | USW-Pro-48-PoE (600W) |
| 480–750W | 938W | Two switches | Split zones across two USW-Pro-48-PoE (600W each) |
| 750W+ | Varies | Multi-switch design | Contact 2M Technology for IDF zone redesign |
⚠ Critical Warnings — UniFi PoE Budget Planning for Commercial Deployments
Never use total port count as capacity planning. A 48-port switch with 185W total PoE budget supports approximately 46 G5 Bullet cameras (at 4W each) or 9 AI Pro cameras (at 20W each) — not 48 of anything. Always calculate the actual device load, never assume port count equals camera count.
Never connect PoE+ devices (802.3at) to 802.3af-only switch ports. The device will either fail to power on, operate in a degraded mode with limited features, or restart intermittently. PTZ cameras, AI Turret, AI Pro, and most Wi-Fi 6/7 APs require 802.3at PoE+ minimum.
Always install UPS on every IDF closet — no exceptions. A power blink that drops IDF switches kills cameras, APs, and access readers simultaneously — precisely when those systems are most needed. Size UPS for 100% of switch PoE load plus switch overhead with a minimum 15-minute runtime.
Verify per-port PoE standard before connecting high-power devices. Some UniFi switches provide PoE++ on only a subset of ports. Connect a Wi-Fi 7 AP requiring 45W to a port rated for only 30W (PoE+) and the AP will either not reach full performance or refuse to power on.
9. Common PoE Planning Mistakes
The most expensive UniFi PoE budget planning mistakes happen before a single cable is pulled — at the switch selection stage.
- Connecting PoE+ devices to 802.3af-only switches: A PoE-only switch will refuse to power a PoE+ device, or worse, attempt to power it at reduced voltage causing instability
- Using total port count as capacity planning: A 48-port switch with 185 W total budget is not a 48-camera switch — it’s a 46-camera G5 Bullet switch or a 9-camera AI Pro switch
- Ignoring startup surge: During a power cycle event, all cameras attempt to draw maximum power simultaneously — budget for this scenario in addition to steady-state consumption
- Mixing PoE standards on the same switch without checking per-port capability: Some switches provide PoE++ on only a subset of ports — verify per-port capabilities before connecting high-power devices
- No UPS on IDF switches: A power outage that drops all cameras simultaneously prevents incident documentation precisely when footage matters most — protect IDF switches with UPS
10. PoE Planning Checklist
Use this UniFi PoE budget planning checklist on every commercial deployment before hardware is ordered.
- ✓ List all PoE devices per IDF switch zone with max power draw
- ✓ Sum total power draw per switch zone
- ✓ Apply 20% safety margin and select appropriate switch model
- ✓ Verify PoE standard (af/at/bt) matches per-device requirement
- ✓ Confirm per-port PoE++ capability for Wi-Fi 7 APs and high-draw devices
- ✓ Verify all cable runs under 100 m; plan Cat6 for runs over 60 m
- ✓ Size UPS for each IDF switch at 100% PoE load + switch draw
- ✓ Set PoE priority in UniFi for critical devices (access control, primary cameras)
- ✓ Verify PoE consumption in UniFi Network post-installation
- ✓ Document PoE budget utilization as part of as-built documentation
UniFi PoE Budget Planning Services by 2M Technology
Frequently Asked Questions
What happens if I connect a PoE+ device to a PoE-only port?
The switch will attempt to negotiate PoE class with the device. If the device requires more power than an 802.3af port can deliver (12.95 W at device), the device will either not power on, power on in a degraded mode with limited features, or restart intermittently. PTZ cameras, AI cameras, and most Wi-Fi 6/7 APs require PoE+ (802.3at) or higher. Never connect PoE+ devices to 802.3af-only switches.
Can I use a PoE injector for a single high-power camera?
Yes — PoE injectors are a practical solution when a single PoE+ camera must be powered from a port on an 802.3af switch, or when adding a camera to a switch that has exhausted its PoE budget. However, in commercial deployments, injectors should be exceptions, not the design pattern. They add failure points, require separate power management, and don’t scale cleanly. If multiple injectors are needed, the switch is undersized — upgrade the switch.
How does PoE budget affect my choice of UniFi switch?
The PoE budget is often more constraining than port count in commercial camera deployments. A facility with 30 AI Turret cameras (20 W each) needs a minimum of 750 W of PoE budget across its switches — the USW-Enterprise-48-PoE at 600 W per unit is insufficient for a single switch solution. Two switches or a higher-capacity aggregate solution is required. Always calculate budget before selecting switch hardware.
Does 2M Technology calculate PoE budgets as part of a deployment quote?
Yes. Every 2M Technology commercial switching infrastructure engagement includes a full PoE load calculation per switch zone, switch recommendation with documented headroom, and UPS sizing for each IDF closet. We do not install systems without verifying the PoE infrastructure matches the device load — this is included in every commercial site assessment at no charge.
Related Deployment Guides — Plan the Full System
Accurate UniFi PoE budget planning requires knowing what every device draws. These guides provide per-device context:
Get a PoE Design Review for Your Facility
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- (214) 988-4302
- sales@2mtechnology.net
The PoE Standards Behind These Numbers
Every wattage figure in this guide traces back to the IEEE 802.3 Ethernet Working Group, which defines the Power-over-Ethernet classes: 802.3af (Type 1) delivers up to 15.4 W per port, 802.3at (Type 2, “PoE+”) up to 30 W, and 802.3bt raises that to 60 W (Type 3) and 90–100 W (Type 4) for high-draw devices like PTZ cameras and access hubs. When sizing a UniFi switch, budget against the standard’s per-port class of each device — not the marketing wattage — and keep total draw under the switch’s PoE budget with 20% headroom, per Ubiquiti’s official specifications.
