In a surveillance network you cannot size a switch by "buy as many ports as cameras." Port count = camera channels + 1–2 reserved uplink ports; total PoE power = per-camera wattage at the device × channels × 1.2 margin. Port and power are the two things that decide a monitoring-project industrial switch. Get these two clear before you pick a model, and you will not find on go-live day that the ports are full yet the power will not hold.
Ports = camera channels + 1–2 uplink. An 8-channel job picks a 16-port model; 16 channels picks 24 ports.
Total power ≈ per-camera watts × channels × 1.2. The 1.2 covers cable loss and later expansion — use the watts the device actually receives, not the PSE nameplate.
A 24-port unit may only budget 250W; 24 × 15.4W PDs need 369W, so it overloads and drops. The limit is watts, not ports.
PTZ domes pull ~26W; mixing them roughly doubles the budget and forces the load onto 802.3at/bt ports.
The downlink ports on the access switch feed cameras; the uplink port feeds the NVR or core. Many newcomers buy ports to match the camera count: 8 cameras, 8 ports — then the uplink has nowhere to go. The right move is camera ports + 1 uplink; add +1 more for redundancy (ring or stack). So 8 channels pick a 16-port model, 16 channels pick a 24-port model — the port count is basically settled. An 8 port poe switch fits the 8-channel entry, and a network switch 24 port suits the 16-channel tier; either way the uplink still comes out of the port count. Remember to pull the uplink out of the PoE budget: it carries data only, no power.
Whether a poe switch 16 port can carry the load is about watts, not ports. Per-camera power uses the watts the device actually receives: the common 802.3af dome/gun gets about 13W at the device (PSE rated 15.4W), a PTZ speed dome about 26W. The poe powered device — the camera itself — draws the watts you size for, and a poe switch 8 port at the edge follows the same power math as a larger unit. Total power is one formula:
Total ≈ per-camera watts × channels × 1.2
The 1.2 packs in cable loss and headroom for later expansion or inrush. Bump it to 1.3–1.4 for more safety, especially in hot industrial sites. Note: use the received watts, not the PSE nameplate, or you under-count the cable loss.
Below assumes 13W per camera and ×1.2; the model tier shows only the port class and whole-unit budget.
| Camera channels | Recommended switch ports (incl. uplink) | Required total PoE power (≈13W × 1.2) | Model tier advice |
|---|---|---|---|
| 8 channels | 8 + 2 = 10 → pick 16-port PoE | 13×8×1.2 ≈ 125W | Entry 8/16 port, whole-unit budget ≥150W |
| 16 channels | 16 + 2 = 18 → pick 24-port PoE | 13×16×1.2 ≈ 250W | 24 port, whole-unit budget ≥250W |
| 32 channels | 32 + 2 = 34 → 2×24 or 48 port | 13×32×1.2 ≈ 500W | 48 port or 2×24 (each ≥250W) |
| 64 channels | 64 + 2 = 66 → 2×48 or rack stack | 13×64×1.2 ≈ 1000W | Total budget ≥1000W, split 2×48 or a big-budget unit |
If you mix in PTZ (about 26W at device), swap the per-camera watts to 26W and recompute; at 64 channels with half PTZ the power approaches 1500W and must be split across units.
Note: The 1.2 uses the watts the camera receives, not the PSE nameplate. Counting the 15.4W label under-counts the cable loss and leaves you short on go-live day.
The table above assumes all 13W domes. The moment you add PTZ domes (26W) or heated pan-tilt units (higher), swap the per-camera watts to the real value. Take 64 channels: all 13W is about 1000W; if half are PTZ (32×13 + 32×26 = 416 + 832 = 1248W, ×1.2 ≈ 1500W), a single switch budget cannot hold it — you must split across 2–3 units, and the high-power points must land on 802.3at/bt ports.
Counting the uplink as a PoE port. The uplink carries data only; counting it in the power budget wastes it and misjudges the model.
Ports enough, watts short. 24 ports stuffed with 24 PDs at 15.4W need 369W; many 24-port units budget only 250W whole-unit, so full load drops.
Driving PTZ from an af port. PTZ needs 25W; an af port gives 15.4W and rejects the load.
No derating on long cable. Pulling 150 m but budgeting loss at 100 m, the far camera reboots.
Treats non-standard PoE as a treasure. Knock-off "high-power PoE" lacks short-circuit protection; an aged short on a pole-line drags the whole network down. Standard 802.3af/at/bt is what stays up.
List each point's powered watts and total channels.
Ports = channels + 1~2 (uplink reserve).
Total power = per-camera watts × channels × 1.2.
Match the model tier: port class AND whole-unit PoE budget both satisfied.
Land high-power points on at/bt ports; in industrial sites leave another 20% temperature margin.
For selection, reference Rayin's PoE power solutions directly on the site.
1. How do I calculate surveillance switch port count? Ports = camera channels + 1–2 uplink reserve. The uplink feeds the NVR or core and takes no camera. 8 channels pick 16 ports, 16 channels pick 24; add +1 for redundancy.
2. How do I estimate total PoE power? Per-camera watts at device × channels × 1.2. The 1.2 covers cable loss and margin. A 13W dome at 16 channels is about 250W; 32 channels about 500W; 64 about 1000W.
3. Why can't a 24-port PoE drive 24 cameras? The limit is whole-unit watts, not ports. 24 × 15.4W ≈ 369W, but many 24-port units budget only 250W — full load overloads and drops. Check the PoE budget first.
4. How do I handle mixed PTZ domes? PTZ receives about 26W; swap the per-camera watts to 26W and recompute, and those points must land on 802.3at/bt ports. At 64 channels with half PTZ the power nears 1500W and must split across units.
Customer Manager at Shenzhen Rayin Technology Co., Ltd.
