Buying Guide · PoE Switch Sizing
PoE switch sizing for commercial security cameras.
A field-side walkthrough for installers spec’ing PoE switches into commercial surveillance deployments — total power budget math, port-count planning, PoE standard selection, and the redundancy decisions that decide whether the system stays up under load.
01 / PoE Standards Cheat Sheet
Three standards. Different watts.
Get this wrong and your PTZ resets every time it pans full-range. PoE classes installers care about for surveillance:
───────── ────── ──────────── ────────────── ──────────────────────────
802.3af Type 1 15.4W 12.95W Fixed bullet/dome cameras
802.3at Type 2 30W 25.5W PTZ, IR cameras, AI models
802.3bt Type 3 60W 51W Heaters, multi-imager, AP
802.3bt Type 4 90-100W 71W High-power devices, displays
Practical rule: spec PoE+ (802.3at, 30W) as your default for any new camera install. PTZ and IR-capable cameras with heaters need PoE+ at minimum; cheap PoE (15W) starves them under cold-weather load — common Ottawa-winter failure mode.
02 / Total Power Budget Math
Camera count × camera watts × headroom.
Switch power budget is the TOTAL wattage the switch can deliver across all PoE ports simultaneously. It’s almost always LESS than (port count × per-port max). Read the spec sheet.
─────────────────────────────────────────────────────────────
6 × PTZ (25W each, peak) = 150W
10 × fixed bullet (12W each) = 120W
Subtotal load = 270W
Spike margin (×1.3 for IR/heater) = 351W
Headroom (×1.2 for future expansion) = ~420W
→ Spec a 16-port PoE+ switch with at least 400W total budget
→ OR 24-port at 370W if expansion expected
The cheap 16-port PoE+ switches on consumer marketplaces typically advertise 30W per port but ship with a 240W total budget — meaning you can fully load only 8 ports at PoE+. Read the total budget number, not the per-port max.
03 / Port Count Planning
Camera ports + uplinks + future.
Sizing port count by camera count alone is a common undersizing mistake. The full math:
- PoE ports for cameras — one per camera, plus 20% for expansion.
- Uplink ports — at least 1Gbps non-PoE uplink to the NVR or core switch. SFP uplink for fiber runs.
- Management interface — out-of-band management port if the switch supports it; useful for site-wide monitoring tools.
- PoE for non-camera devices — access control readers if they share the IP network, intercom panels, WAPs.
- Spare ports — 1-2 ports left open for site-survey laptops, replacement-camera staging.
Typical sizing: a 16-camera install runs cleanly on a 24-port managed PoE+ switch with two SFP uplinks. An 8-camera site on a 16-port managed PoE+ switch with one SFP uplink. Smaller than that, you’re typically into the consumer category and not building for commercial reliability.
04 / Managed vs Unmanaged
Spec managed for anything commercial.
Unmanaged PoE switches are cheaper but blind. For commercial installs, managed is the right default. Why:
- VLAN segmentation — keep camera traffic off the corporate LAN. Required for any decent network security posture.
- SNMP / monitoring — the only way you find out a port is power-cycling is via SNMP traps. Unmanaged switches don’t talk back.
- PoE port control — power-cycle a hung camera remotely from the switch UI instead of climbing a ladder.
- QoS — give camera traffic priority over chatty IoT devices sharing infrastructure.
- 802.1X authentication — port-level device authentication, important for any site with security or compliance posture.
Some commercial customers will push back on the price difference. Frame it as: “$400 more upfront, $1000 saved per truck roll over the project lifetime.” Truck rolls add up.
05 / Compatibility & Brand Notes
What we stock for security backbones.
Our networking catalog focuses on switches sized for security backbones — not generic office data. Stocked brands include Cisco, Ubiquiti, Netgear ProSAFE, TP-Link Omada, Tripp Lite, Panduit, Hubbell. NDAA-aware projects get Cisco or Aruba defaults — see the access control buying guide for the integrator-platform pairings and the contact desk for spec-verified quotes.
PoE Spec Review
Spec’ing PoE infrastructure for a project?
Send the camera count, model mix, and uplink requirements — we come back with switch options sized for your total budget, NDAA constraints, and Ottawa-winter operational reality.
Equipment Referenced · Networking
PoE switches and accessories in this guide.
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