PoE Switch Guide: Power Budget, Ports and Sizing for CCTV (2026)

Choosing a "poe switch" by port count alone is how a camera system dies at 02:00. Sixteen 4MP cameras each draw roughly 8-10 W with their infrared arrays on. That is 128-160 W in total. A switch with sixteen ports but a 120 W PoE budget starts dropping cameras the moment dusk hits. The footage you need is the footage it never recorded.

This guide covers what power over ethernet is, how the 802.3af, 802.3at and 802.3bt standards differ, and typical camera power draw. It walks through a step-by-step poe budget calculation with a worked calculator table, plus port count and uplink sizing. It also covers when a poe injector beats a switch, VLAN isolation, the poe vs wifi decision, and a procurement checklist for business buyers. By the end you can size a switch that survives its own night shift.

Keep reading for more!

The Snapshot

• Power over ethernet sends DC power and network data over one Cat5e or Cat6 cable, up to 100 m per run. One cable replaces the video cable, the network cable and the 12 V adapter.
• Three standards matter: 802.3af (15.4 W per port), 802.3at (30 W) and 802.3bt (60 W or 90 W). The power available at the camera is lower than the port rating, so always check the device-side figure.
• A typical 4MP PoE camera draws 5-10 W. A 5MP full-color unit with white light runs 7-12 W, and a PTZ can draw 15-30 W with its motors and heaters.
• The poe budget is the switch's total deliverable watts, not its port count. A common 16-port PoE+ switch carries a 250 W budget, which is far less than 16 times 30 W.
• Size the budget as the sum of peak draws plus 20% headroom. A 16-camera site at 9 W each needs about 173 W, which lands on a 250 W switch.

What Is Power over Ethernet?

Power over Ethernet (PoE) is a method of delivering DC power and network data over the same twisted-pair cable. The IEEE standardized it in 2003 as 802.3af, extended it in 2009 as 802.3at, and added 802.3bt in 2018. For CCTV, PoE means a camera needs only one cable from the switch. That cable carries both the video stream and the electricity that runs the camera.

In a PoE system, the switch acts as the power sourcing equipment (PSE) and the camera is the powered device (PD). The switch injects 44-57 V DC onto the spare pairs or the data pairs, and the camera negotiates how much it needs. The 802.3 handshake prevents over-powering. A camera that asks for 9 W only receives 9 W. A non-PoE device plugged into the port is left untouched. That negotiation is why standards-compliant PoE is safe to mix with ordinary office equipment.

The practical gain for a camera installer is a single point of power control. Cameras mounted at 4-6 m height need no local adapter, no power outlet on the wall, and no electrician to wire a second circuit. Reboots happen remotely from the switch, and a UPS at the rack keeps every camera alive through a brief outage. The failure surface shrinks from three cables per camera to one.

PoE also has a hard physical limit that shapes every design: 100 m. The Ethernet standard rates Cat5e and Cat6 cable for 100 m of data transmission, and power delivery weakens over distance as well. Runs beyond 100 m need a PoE extender, a media converter to fiber, or a second switch closer to the cameras. Plan the cable survey before you buy the switch.

802.3af vs 802.3at vs 802.3bt: Standards Explained

The IEEE PoE standards define how much power a port may deliver. The table below shows the four ratings that matter for CCTV. It lists the maximum power at the switch and the power actually available at the camera.

← swipe to scroll →

For a modern CCTV site, 802.3at is the practical default. A 4MP camera with infrared on typically needs 8-10 W, and a 5MP full-color unit needs up to 12 W. Both sit comfortably inside the 25.5 W that 802.3at delivers at the camera, with margin for voltage drop on a long cable. 802.3af still runs small 2MP cameras, but it leaves no headroom for IR arrays, heaters or future upgrades.

802.3bt exists for the heavy loads: PTZ cameras with wipers and heaters, high-power floodlight cameras, and access control panels. The jump matters at budget time. A port that can deliver 90 W demands a much larger total budget than a port capped at 30 W. Most 802.3bt switches also cost noticeably more per port.

One warning for buyers: some low-cost equipment uses passive or non-standard 48 V PoE with no negotiation handshake. It can power a matching camera, but it can also damage a device that does not expect voltage on the line. Buy 802.3af, 802.3at or 802.3bt compliant switches and cameras, and confirm the standard is printed on the spec sheet.

How Much Power Does a PoE Camera Draw?

The poe camera power figure drives everything downstream: switch budget, UPS size, and cable choices. The honest number to use is the camera's maximum draw, not the marketing wattage. That maximum is what happens at night with infrared or white light on full.

← swipe to scroll →

Infrared illuminators add roughly 2-4 W per camera when they switch on at dusk. Full-color night vision cameras replace the IR array with white light LEDs. That draws similar or slightly more power. The F1.0 lens keeps the sensor sensitive enough to need less fill light overall. A 5MP full-color unit therefore lands around 7-12 W in typical night operation.

The spec sheet tells you the maximum: read the line labeled "max power consumption" and use that number in your budget. A camera listed as 8 W typical can spike to 12 W when the heater cycles or the IR array steps up. A budget built on typical figures fails exactly when the site needs the cameras most.

PoE Budget: How to Calculate It

The poe budget is the total wattage a switch can deliver to all its PoE ports at once. It is always smaller than the port count multiplied by the per-port maximum. A 16-port 802.3at switch, for example, can theoretically deliver 480 W, but its internal power supply typically budgets 250 W. The budget number is the one that matters.

The calculation is three steps. First, list every camera and its maximum draw from the spec sheet. Second, add the draws together. Third, add 20% headroom for IR spikes, future cameras and voltage drop on long runs. The switch you buy must have a PoE budget at least equal to that final number, on top of its own operating power.

← swipe to scroll →

Run the same math on the recorder side. Many PoE NVRs ship with eight or sixteen built-in PoE ports and their own internal budget, often 120-250 W depending on the model. If the NVR powers the cameras, the NVR's budget replaces the switch budget, and the uplink to the network is a single gigabit port.

Two rules keep the budget honest. First, use maximum draws, not typical ones. Second, treat the budget as a shared pool. The switch does not reserve 30 W per port. It hands out from a single pool until the pool is empty. Exceeding the pool triggers port shutdowns or under-voltage reboots, which is the 02:00 failure mode this guide started with.

Port Count and Uplink Speed

Port count is the second number on the box, and it is easier to size. Count every camera, add the NVR or uplink connection, and add spare capacity for growth. Integrators typically spec 20-30% spare ports, so a 13-camera site lands on a 16-port switch and a 20-camera site on a 24-port one.

The uplink matters less than most buyers think. A 4MP camera with H.265+ streams roughly 2-4 Mbps. Sixteen of them total 32-64 Mbps, which a single gigabit uplink handles with enormous margin. Bandwidth pressure appears only with 8MP cameras, high frame rates, or dozens of cameras on one switch. Even then, a gigabit uplink usually suffices below 40-50 cameras.

Small sites can skip the standalone switch entirely. A PoE NVR with eight built-in PoE ports powers and records eight cameras with one box. It is the cheapest clean solution for a small office or shop. The same budget and cable rules apply to the NVR's internal ports, and the NVR typically adds a gigabit LAN port for remote viewing.

For larger sites, think in terms of switch tiers. Cameras connect to PoE switches in the field. Those switches uplink to a core switch or directly to the NVR. A 48-port PoE switch with four SFP fiber slots is a common building block for warehouses. Fiber links between buildings beat long copper runs past the 100 m limit.

PoE Switch vs PoE Injector

A poe injector is a small single-port device that adds power to a cable between an ordinary switch and one camera. You plug the switch cable in one side and the camera cable in the other. The injector then supplies 802.3af or 802.3at power over the line. An injector costs a fraction of a switch and solves a one-camera problem cleanly.

Use an injector when the camera count is one to three. It also fits when the existing switch is not PoE. Another case is one camera far from the switch and near a power outlet. Keep a spare injector in the van for field repairs, since it is the cheapest single-point fix in CCTV. Buy 802.3at injectors even for 2MP cameras so the spare works on any camera.

The switch wins at four cameras and up. A switch gives centralized power, per-port remote reboot, budget monitoring, and one UPS at the rack instead of injectors scattered across the ceiling. It also costs less per port than four separate injectors once you count installation time.

Within switches, the choice is unmanaged, smart managed, or fully managed. Unmanaged switches are plug-and-play and fine below eight cameras. Smart managed switches add per-port PoE on and off, budget monitoring and VLANs, which is the typical integrator default. Fully managed switches add 802.1X authentication, link aggregation and SNMP monitoring for enterprise sites.

VLAN and Managed Switches

A VLAN (virtual local area network) splits one physical switch into separate logical networks. For CCTV, the standard design is a dedicated camera VLAN. It carries only camera and NVR traffic, isolated from the office network that carries employee computers and phones. The camera VLAN needs a managed or smart managed switch, since unmanaged switches cannot segment traffic.

Isolation earns its keep in two ways. First, bandwidth: a broadcast storm or a heavy download on the office network never touches the camera stream. Second, security: if an outdoor camera is compromised, the attacker lands inside an isolated VLAN with no direct path to office machines. The NVR sits on the camera VLAN and exposes only its management interface.

Quality of service (QoS) is the companion setting. Marking video traffic with 802.1p priority tells the switch to forward camera streams ahead of bulk traffic during congestion. On a gigabit network with a handful of cameras, QoS rarely changes anything. On a shared 100 Mbps uplink or a busy multi-tenant building, it prevents the jitter and frame drops that ruin recordings.

For multi-site integrators, VLAN design also simplifies remote access. The management VLAN carries the VPN. The camera VLAN stays local, and a firewall rule controls what crosses between them. This is the layout behind most professional camera installations, and it costs nothing extra in hardware once you choose a smart managed switch.

PoE vs WiFi Cameras: When Each Wins

The poe vs wifi decision comes down to cabling versus flexibility. A PoE camera is wired: full bandwidth, no radio interference, powered over the same cable, and limited to 100 m from the switch. A WiFi camera needs no data cable, but it still needs power, and its bandwidth is shared with every other device on the access point.

For fixed outdoor coverage, meaning perimeter walls, gates and parking lots, PoE is the standard answer. The camera gets continuous power, the stream is immune to Wi-Fi congestion, and the wired link keeps latency low for live viewing. Full-color night vision cameras also benefit, since their white light LEDs draw steady power that wireless batteries cannot sustain for long.

WiFi earns its place in retrofit and temporary scenarios. Consider renting a space, a heritage building where drilling is forbidden, or a site that changes layout monthly. A WiFi camera with a local power outlet deploys in minutes. The trade-off is real, though. A busy office with twenty access points can push camera streams into contention, and a WiFi camera drops offline entirely when the access point restarts.

Most business sites end up hybrid: PoE cameras on the perimeter and critical doors, WiFi cameras for the temporary or hard-to-cable spots. When a customer asks for "wireless" because they fear cabling cost, show the single cable per camera and the 100 m reach. The install cost is usually close, and the reliability gap is large.

How to Choose: Checklist for Business Buyers

Work through this checklist in order, and every item maps to a line on the supplier's spec sheet.

• 1. Count cameras and list their maximum draws. Pull the "max power consumption" figure from each camera spec sheet, not the typical figure.
• 2. Add 20% headroom. Multiply the total by 1.2 to cover IR spikes and future cameras.
• 3. Default to 802.3at. It powers every 4MP and 5MP camera with margin, and 802.3bt stays reserved for PTZ and heater loads.
• 4. Choose the port count with 20-30% spare. A 13-camera site gets a 16-port switch.
• 5. Confirm the PoE budget in watts. The budget must cover the headroom total, not the theoretical port maximum.
• 6. Check the uplink. Gigabit handles 16-32 cameras at 4MP with H.265+, and fiber covers the longer runs.
• 7. Decide managed or unmanaged. Choose smart managed when you need VLAN isolation or per-port reboot.
• 8. Plan every run under 100 m. Longer runs get a field switch, an extender, or fiber.

For procurement, build the list before you order. It includes the poe switch for cctv itself and two spare 802.3at poe injectors. Add surge protectors on outdoor runs and a UPS sized to the switch budget plus 30%. Finish with Cat5e or Cat6 cable and a documented distance per run. A wholesale buyer should also ask the supplier for the switch's real power budget in watts, the warranty period, and the port failure rate history. Those three questions separate a camera distributor from a box shipper.

Buyers often over-spec the switch and under-spec the power. A 48-port switch that cannot deliver half its theoretical maximum is a common catalog trap. The spec line that decides the sale is "PoE budget: 400 W", not "48 ports". When a supplier quotes a switch, ask for the budget number in writing and compare it against your headroom total from step 2.

PoE Switch Questions Buyers Ask

The Bottom Line

Size the poe switch for cctv by watts, not by ports. Sum the camera maximum draws and add 20% headroom. Default to 802.3at and keep every run under 100 m. Port count and uplink speed are the easy numbers, and the PoE budget is the number that decides whether the site records all night. Buy 802.3 compliant hardware, choose smart managed when the site needs VLANs, and put the budget in writing on every quote.

At FULLCOLORCAM we build 4MP and 5MP full-color night vision PoE cameras with 1/1.8-inch sensors and F1.0 lenses. They record in H.265+ and ship tested, ONVIF-conformant. Send us your camera count, cable distances and site plan for a spec-matched quote. We will tell you the PoE budget, switch model and NVR your project actually needs. That is a real spec, not the biggest port count we can sell.