— PoE Budget · Networking
Office floor closet — 38 PoE devices, 416 W pool
Problem. A single office floor's comms closet has to power a mix of Wi-Fi 6 access points, fixed cameras and desk phones from one PoE switch. The question is not whether any single port can drive its device — they all sit inside PoE+ limits — but whether one switch's shared power pool can carry the whole floor at once.
Answer. Six Wi-Fi 6 APs at 18 W, twelve fixed cameras at 6 W and twenty VoIP phones at 7 W total 320 W of device draw; with the tool's 30% design headroom that becomes 416 W, which clears the 380 W single-24-port budget and lands on a 48-port L2 managed PoE+ switch (740 W pool). The tier here is set by the aggregate pool, not by any one hungry port.
02 / In depth
How this preset reads — the engineering view.
PoE sizing has two independent floors. The per-port floor asks what IEEE class the single hungriest device needs at the powered-device (PD) end — 802.3af at or below 12.95 W, PoE+ at or below 25.5 W, 802.3bt Type 3 at or below 51 W, Type 4 at or below 71 W. The aggregate floor asks whether the switch's shared power pool covers the sum of every device plus a 30% design margin. The recommended tier is the higher of the two, because a switch that fails either test cannot run the floor.
For this closet the device load is 6×18 + 12×6 + 20×7 = 108 + 72 + 140 = 320 W. Adding 30% headroom gives 416 W. The hungriest device is an 18 W Wi-Fi 6 AP, which sits inside the 25.5 W PoE+ PD ceiling, so the per-port floor is only PoE+ and does not push the tier up. The 416 W pool, however, exceeds the 380 W that a 24-port PoE+ switch offers, so the aggregate floor selects the 48-port L2 managed PoE+ class with a 740 W shared pool across 38 powered devices.
The result moves with total wattage: add more APs, cameras or phones and the 416 W figure climbs monotonically toward the 740 W ceiling and eventually into a higher tier. Swapping a fixed camera for an IR or PTZ head raises both the per-device draw and, if the largest device crosses 25.5 W or 51 W, the per-port class floor as well. Nothing you add lowers the requirement — the pool only grows.
The tool sizes the power pool and the port class; it deliberately does not lay out cabling runs, model Cat6a distance derating, size uplinks or redundancy, or account for simultaneous-peak versus average draw beyond the flat 30% margin. It assumes one logical switch stage — real floors may split load across stacked units or distribution closets, and standby PoE for critical devices is a design choice made outside this estimate.
What this preset deliberately does not solve
- Models a single shared power pool, not multi-switch stacks or uplink sizing.
- The 30% headroom is a flat design margin, not a measured peak-versus-average profile.
- Device wattages are conservative typicals; verify each PD against its own datasheet.
How this preset differs from its siblings
This preset is aggregate-driven: every device sits inside PoE+, so the tier is set purely by the summed 416 W pool. Its sibling, the perimeter PTZ drop, is the opposite case — a small total load whose single 55 W heated PTZ forces a Type 4 tier on the per-port floor. Use this one to reason about how many devices a shared pool can carry; use the perimeter preset to see how one demanding device dictates the switch class.
03 / Hydrated calculator
Try the configuration — live.
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Premium consultation · 38 devices
48-port L2 managed PoE+
A 320 W device load + 30% headroom lands at 416 W per closet — tier sized to cover both the pool and the largest single device's per-port class.
Recommended budget
416 W
320 W draw + 30% headroom
Devices counted
38
across all PoE classes
Switch tier
Tier 3
48-port L2 managed PoE+
Reference SKU class
Aruba 6100 48G · Cisco Catalyst 1300-48P
engineering reference, not a quote
Assumptions driving this recommendation↓ expand
- Wattage class source
- IEEE 802.3 af / at / bt class tables
- PSE-to-PD derating
- Per IEEE 802.3bt
- Cabling standard
- TIA/EIA-568-C · ISO/IEC 11801 Cat6A
- PoE headroom
- 30%
- Wi-Fi 6/6E AP
- 18 W typical draw
- Wi-Fi 7 AP
- 32 W (PoE++ Type 3)
- Fixed camera
- 6 W
- PTZ (heated)
- 55 W (802.3bt Type 4)
- Switch budget
- 740 W per 48-port chassis
Operationally sensible ecosystem
Brands grouped by engineering role — not random logos.
Network backbone
Core switching + routing + firewall
- HPE Aruba 6100L2 managed PoE+ for mid-market
- Cisco Catalyst 1300L2 managed PoE+ alternative
- FortiGateMid-market UTM firewall
Wi-Fi access
High-density Wi-Fi 6E / Wi-Fi 7
- HPE Aruba 530Wi-Fi 6E for enterprises
- Cisco Catalyst 9120Wi-Fi 6E with controller
IP cameras
Cameras + analytics edge
- Hanwha WisenetKorean enterprise vendor
- Bosch IPEuropean optics + analytics
- Hikvision ProMid-tier Hikvision product line
Indicative — class wattages per IEEE 802.3 af / at / bt tables; PoE budget is a shared pool across ports, not a per-port figure. Long cable runs derate delivered power per IEEE 802.3bt PSE-to-PD budgeting; production designs ship with a per-port budget allocation spreadsheet.
A planning link that reopens this exact configuration — not a quote.
PoE budget is a shared pool
A 48-port PoE+ switch with 740 W cannot drive 30 W per port simultaneously — only about 24 of the 48 ports can run at the full 30 W at once.
High-draw devices need 802.3bt
Wi-Fi 7 APs draw about 32 W — above the 25.5 W a PoE+ port can deliver to the device — so specify 802.3bt Type 3 (60 W) ports. Heated PTZ cameras at 55 W go further and need Type 4 (90 W) ports.
30% headroom is the rule
Five-year refresh cycles see device counts grow about 6% a year. 30% spare keeps the switch in budget across the cycle.
Stack above 1,800 W
A single chassis tops out at ~1,800 W in most enterprise-tier switches; beyond that, stack two or move to a chassis with dual PSUs.
Pricing · written estimate after review
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