One of the biggest cost drivers in a CCTV installation isn't the cameras — it's the cabling. Every traditional camera needs two things: a data cable back to the recorder, and a power cable to a nearby socket or a central power supply. That second cable often means trunking, wall chases and an electrician's bill. Power over Ethernet — PoE — eliminates it: one standard network cable carries both the video signal and the electricity the camera needs. Here's how it works, where it helps, and where you need to know its limits.
How PoE works
PoE sends low-voltage DC power down the same twisted-pair cable that carries your network data. The power source — usually a PoE switch, or an NVR with built-in PoE ports — injects the power at one end; the camera, which is built as a PoE-powered device, draws what it needs at the other. A device that doesn't support PoE simply doesn't draw power, so a PoE port is safe to plug any standard Ethernet device into — a laptop won't be harmed by it.
PoE comes in defined standards, which is why a camera's power needs must match the power source. The three you'll encounter in CCTV:
- PoE (IEEE 802.3af): up to about 15W per port — enough for most fixed IP cameras.
- PoE+ (IEEE 802.3at): up to about 30W per port — needed by many motorised PTZ cameras and cameras with heaters.
- PoE++ (IEEE 802.3bt): up to about 60–90W — for high-power devices such as multi-sensor panoramic cameras.
Always check the camera's specification sheet: connecting a 25W PTZ camera to a 15W PoE port doesn't just underperform — the camera may not boot at all.
Why installers (and finance teams) love it
The practical benefits are hard to argue with. First, one cable per camera: no power runs to plan, no sockets to install near each camera, no separate electrician scope. In retrofit projects — a working office, a shop that can't close — this cuts disruption dramatically. Second, centralised power: with all cameras powered from the switch or NVR, a single UPS in the server room keeps the entire camera system running through a power cut, which standalone 12V supplies scattered around a building can't match. Third, flexibility: moving a camera means pulling one cable, not two. And fourth, remote power cycling: a camera that freezes can often be rebooted by toggling its PoE port from the switch's management interface — no ladder required.
The 100-metre rule — and how to handle longer runs
PoE's main limit is distance: like all Ethernet, it runs over a maximum of 100 metres of cable from switch to device. In most offices, warehouses and showrooms that's plenty. For long perimeter runs, gate cameras or car parks, you have options: place a PoE switch or extender partway, use a mid-span PoE injector with a fibre link for the long stretch, or locate the NVR closer to the cameras. This is exactly the kind of planning a proper site survey settles before anyone buys hardware.
Power budgets: the mistake we see most
A PoE switch has two limits that matter: the power available per port and the total power budget across all ports. A 16-port switch rated at 150W total cannot feed 16 cameras drawing 25W each — and when the budget is exceeded, cameras may behave erratically or fail to start. Add up every camera's rated draw, add 20–30% headroom for cold-boot surges, and size the switch (or switches) to that total. PTZ cameras, cameras with built-in heaters or wipers, and infrared illuminators are the usual budget-busters. When in doubt, one PoE++ port costs less than a second site visit.
PoE NVRs vs separate PoE switches
Many NVRs now come with built-in PoE ports — typically 8 or 16. That's the simplest architecture for small-to-medium installs: cameras plug straight into the NVR, the camera network stays separate from your office LAN, and there's one device to manage. Separate PoE switches make more sense when cameras are spread across a building (one switch per floor or wing, uplinked back to the NVR), when you need PoE+ or PoE++ ports the NVR doesn't offer, or when the install exceeds the NVR's port count. Both are standard designs; the right one depends on your layout and growth plans — not brand preference.
Planning checklist before you commit
- Map every camera location and measure cable runs — anything near 100 metres needs a designed solution, not hope.
- Total the power budget camera by camera, with headroom for growth and cold starts.
- Match the PoE standard to each camera's rated draw — especially PTZs and outdoor units.
- Put the PoE switch or NVR on a UPS — centralised power is only an advantage if it stays on during outages.
- Use quality cabling — solid-core Cat6 from a reputable brand handles PoE current and future bandwidth far better than cheap copper-clad cable.
PoE doesn't make CCTV cheaper by itself — it makes the installation simpler, more reliable and much easier to maintain. One cable per camera, central power, remote reboots, and an honest power budget done up front: that's the difference between a system that quietly works for years and one that generates support calls every quarter.
If you're planning a new CCTV system or replacing an old analogue one, we'll design the whole power and data layout properly from the start — camera placement, PoE switch sizing, cable routes and UPS coverage. Request a quote, call us on (04) 359 4874, or message us on WhatsApp at +971 52 562 1946 for a free site survey — and one cable will be the most of it.
