Power and network on site — PoE, splitters, extenders and Wi-Fi

The camera has to go on an outdoor corner where there is no power socket. The gate is 180 metres from the house. The warehouse has Wi-Fi, but the scanner drops its connection exactly when a lorry is being loaded. These are three different problems, but the solution starts in the same place: how to carry data and power together, over one cable, to where you need them. This page goes through what to choose and why — from the practical end, not as a list of specifications.

1. PoE standards — three numbers worth knowing

PoE (Power over Ethernet) means the same network cable carries both data and power. There are three standards and the only difference between them is power:

Standard	Commonly called	Out of the port	Reaching the device	What it is enough for
802.3af	PoE	15.4 W	12.95 W	Most fixed cameras, small access points
802.3at	PoE+	30 W	25.5 W	PTZ cameras, cameras with IR illuminators, stronger APs
802.3bt	PoE++ / Hi-PoE	60 W or 90 W	51 W / 71 W	Heated PTZ, door stations with a screen, Wi-Fi 7 APs

The two numbers differ because part of the power stays in the cable. A hundred metres of twisted pair takes its share — which is why you must not calculate with the port figure, but with what actually reaches the device.

Passive PoE is not a standard. Ubiquiti airMAX devices and some 4G routers use passive 24 V PoE. It does not negotiate with a standard switch: the voltage is on the cable immediately, without anyone asking what is at the other end. A passive device connected to a standard 802.3af/at switch simply will not start; the wrong way round — a passive injector on a standard device — can destroy the device. We have separate injectors for this: POE-24-12W-G (24 V) and POE-48-24W-G (48 V).

When in doubt, measure. A PoE detector (Mode A/B, 24/48 V, af/at) costs under twenty euros and tells you in three seconds what is actually coming out of the port. Cheaper than one burnt camera.

Mode A and Mode B

Power can come either on the data pairs (Mode A: wires 1,2 and 3,6) or on the spare pairs (Mode B: 4,5 and 7,8). Gigabit uses all four pairs, so the difference matters less there, but it does come up with 100 Mbps devices and cheaper injectors. The mode is always stated in our injector descriptions — for example Mode B (4,5 +; 7,8 −).

2. How much power you actually need

The most common mistake when choosing a switch: people look at the number of ports and forget the PoE budget. This is the total power the switch can deliver at once — and it is almost always lower than the number of ports times the per-port maximum.

Example: 8 cameras, an 8-port switch

Eight fixed 4 MP cameras, each drawing about 7 W at night with IR on. That is 56 W in total. A switch with a 60 W budget looks like a fit — but the headroom is 4 W. One cold winter night with the IR at full power and the switch starts shutting ports down. Two cameras disappear without anyone touching anything.

A 110 W model for the same money leaves headroom that also allows a ninth camera later.

Rule of thumb: add up what the devices draw and add 30%. For the same port count our range usually has several budgets, for example the 16-port Dahua at 135 W / 190 W / 240 W — a small difference in price, a large difference in headroom.

What you are connecting	Budget roughly
Fixed IP camera, IR	5–8 W
Camera with white light (Full Color / Dual Light)	8–12 W
PTZ camera	12–25 W
Heated PTZ, in winter	30–60 W → needs the bt standard
Wi-Fi 6 access point	12–20 W
Video intercom door station	7–15 W

3. One trap: 100 Mbps ports

On cheaper PoE switches the camera ports are 10/100 Mbps and only the uplink is gigabit. You can see it in the model name: CS4218-16ET-240 — ET marks 100 Mbps ports, GT gigabit.

For most surveillance systems this is perfectly sufficient: a 4 MP camera stream is usually 4–8 Mbps. But if you are planning 8 MP or 12 MP cameras at a high bitrate, several streams at once (recording + live view + mobile), or you intend to copy archive material through the same switch, then a 100 Mbps port starts to limit you.

A simple check: add up the camera bitrates and see whether the uplink carries them. Eight cameras at 8 Mbps = 64 Mbps — a gigabit uplink handles that easily, but if the recorder sits at the other end behind a 100 Mbps port, that is your bottleneck.

4. PoE splitter — when the device itself does not do PoE

A splitter does the opposite job to PoE: it takes the power off the cable and hands it over as an ordinary 12 V plug, with the data continuing separately over RJ45. This solves one very common problem — the device you need far away does not support PoE.

Example: a 4G router on a pole

The site has no fixed connection, so the router has to go up a mast where there is signal. The router wants a 12 V adapter, but there is no socket on top of a pole. A PoE splitter goes between the switch in the house and the router: one cable to the pole, and the splitter gives the router its 12 V. For outdoor use we have a model in a splash-proof plastic enclosure.

Our splitters cover the more common needs:

Output	When
12 V DC	The most common: 4G router, small monitor, older analogue camera, magnetic lock, sensor
12 V + PoE passthrough	When the same point has to power both a 12 V device and the next PoE device
5 V + LAN	Small devices that want USB power
PoE 48 V → PoE 24 V	Powering a passive 24 V device (e.g. an airMAX radio link) from a standard switch

Check three things before ordering a splitter: the plug size (usually 5.5 × 2.1 mm), the polarity (which contact is positive) and the current the device draws. A splitter provides voltage, but the current is limited — a 12 V/1 A splitter will not run a 2 A device, even if the plug fits.

5. PoE extender — when 100 metres runs out

Ethernet over twisted pair ends at 100 metres. Not "about" — that is the limit in the standard, and past it you start getting packet loss and unexplained dropouts that are very tedious to chase down later.

An extender receives the signal, amplifies it and passes it on — each hop adds up to another 100 metres. Power passes through as well.

Example: a gate 180 metres away

The gate camera and door station are 180 m from the house. That does not reach directly. One extender roughly halfway — at the base of a lamp post or in a manhole, say — and both devices get network and power. We have models both for DIN rail mounting and in enclosures meant for outdoor use.

What an extender does not do: it does not create extra power. If the switch budget is 60 W, the cameras behind the extender eat into that same 60 W, plus the extender itself takes a couple of watts. Three hops in a row also start adding latency — once the distance goes beyond 300 metres, it is worth looking at fibre or ePoE.

6. One cable, several cameras

A frequent situation: three cameras are needed at the gate, but only one cable was run from the house. Pulling a new one would mean digging.

The answer is a PoE extender/switch — a device with one PoE input (uplink) and two to four PoE outputs. It works as an extender and a small switch at the same time: one cable comes from the house and is split into several at the gate.

In the house: an ordinary PoE switch, one port towards the gate.
At the gate: an extender/switch, powered from that same cable.
Onwards from the gate: three short cables to the cameras, all of them on PoE.

We have these with 2, 3 and 4 outputs, some for DIN rail, some for outdoor use. The gigabit versions also suit higher-resolution cameras.

Two limits that get shared. Cameras behind a single cable share both bandwidth and power. Three 8 W cameras = 24 W plus the extender's own draw — that already requires PoE+ (at) rather than af from the port in the house. Check both before you give up on digging.

7. Reusing old coaxial cable — ePoE

The site has an old analogue system, there is RG-59 coax in the walls, and nobody wants to replace it. ePoE lets you use that same cable for an IP camera: both data and power travel over the coax.

Distance	Speed
up to ~400 m of coax	100 Mbps
up to ~800 m of coax	10 Mbps — enough for one camera stream

You need a pair: a transmitter at the camera, a receiver at the recorder. Dahua has the LR1002 series for this, and there are also ePoE switches where some ports are already in ePoE mode and no separate receiver is needed.

Where this saves the most: an industrial building where the cable runs are in concrete; an apartment block where the old system runs through every floor; a car park where the digging would cost more than the whole camera system.

8. When no cable can be run at all

Powerline — data over the mains

A pair of adapters: one in a socket by the router, the other where the network is needed. The data travels over the existing mains wiring. We have kits from 600 Mbps to 1200 Mbps, some with a pass-through socket, so the outlet is not lost.

An honest warning: the real speed of powerline depends on the wiring in the building, and the number on the box is a laboratory figure. Between different phases the link may not come up at all. It works well within one flat or house, badly in an old building between separate distribution boards.

Radio bridge — across a yard or a street

Two directional antennas that "see" each other. This can take the network to an outbuilding, a barn, or the other side of a street. We have both a ready-made kit (two pre-configured devices in one box, up to 5 km) and individual airMAX devices for links up to 10 km.

A requirement you cannot work around: line of sight. A tree in between, the corner of a building, or even heavy rain at 5 GHz will ruin the link. Before ordering, check whether there really is a clear view from point to point — a distance measured off a map does not tell you that.

9. Choosing a Wi-Fi access point

The most common mistake: an AP is picked by its number ("AX3000 must be better than AX1800"). In practice the speed figure rarely decides the outcome. Three other things do.

1) How many devices at once

At home, 10–20 devices — a simple AX1800 AP is enough. In an office or warehouse with 40+ devices at once you need a higher-capacity model (often marked "HD"), which shares airtime more fairly between many clients. The number on the box does not show this — it shows the theoretical peak speed for a single client.

2) Where it physically goes

Location	What to choose
Ceiling, indoors	An ordinary round AP — the most even coverage
Wall, hotel room or flat	A wall-plate model (e.g. -Wall): it replaces a socket and adds LAN ports
Outdoors, barn, terrace	An outdoor AP with an IP-rated enclosure — an ordinary indoor AP will not survive the damp even under a roof
A large open area	Several weaker APs rather than one strong one: the Wi-Fi problem is almost always the device's transmitter, not the AP's

3) Who will manage it afterwards

If there is more than one AP, it is worth staying inside one ecosystem:

TP-Link Omada — a good price-to-capability ratio; the controller is either a separate box (OC200), a router with a built-in controller, or software.
Ubiquiti UniFi — a more mature interface and a better overview, more expensive; the controller can live in a Cloud Gateway device.

In both cases the clients are managed from one place, settings propagate to new APs by themselves, and devices move between APs without dropping the connection. Mix the two and you lose that.

Do not forget the power. Most APs want 802.3af or at PoE. If the switch budget does not stretch, the AP needs its own injector — put that in the calculation straight away, not afterwards.

10. Wi-Fi standards — what the difference really is

Name	Technically	Bands	What it gives you in practice
Wi-Fi 5	802.11ac	5 GHz	Still fine for one or two users. Not what you would buy new, but no reason to replace what is already there.
Wi-Fi 6	802.11ax	2.4 + 5 GHz	The main gain is not speed but behaviour in a crowded network — several devices at once without getting in each other's way. A sensible default today.
Wi-Fi 6E	802.11ax + 6 GHz	2.4 + 5 + 6 GHz	Adds the clean 6 GHz band, where the neighbours' networks are not yet. Requires the end device to support it too.
Wi-Fi 7	802.11be	2.4 + 5 + 6 GHz	Wider channels and using several bands at once. Worth it when the devices are new and the uplink is 2.5 Gb — otherwise the gain stays on paper.

2.4 vs 5 vs 6 GHz

2.4 GHz — far and through walls, but slow and full of the neighbours' networks. Sensors, older devices, the far corner of a warehouse.
5 GHz — a good balance. Most of the work happens here.
6 GHz — fast and clean, but short range and walls absorb it. A single-room solution.

If the uplink is gigabit, going beyond AX3000 adds nothing. A Wi-Fi 7 AP with a 10 Gb port, connected to an ordinary gigabit switch, runs exactly as fast as that switch allows. If you are planning to move to Wi-Fi 6E or 7, look at the switch and the cabling at the same time.

Summary for the decision-maker

Add up the power — what the devices draw plus 30% headroom. That gives you the switch's PoE budget.
Check the standard — af, at or bt. PTZ and heating mean at or bt.
Measure the distance — beyond 100 m means an extender, beyond 300 m means ePoE or fibre.
Look at what cable is already there — coax is not an obstacle but an opportunity.
For Wi-Fi, count devices, not megabits — and stay within one ecosystem.

Browse the products:
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Not sure what suits your site? Get in touch — we will go through the budget and the distances together.

Standard figures: IEEE 802.3af/at/bt. Manufacturer data: Dahua, TP-Link Omada, Ubiquiti UniFi. Exact figures for each product are on its own product page.