Multiple CCTV Cameras on One Cable: What Actually Works

Whether you can run multiple CCTV cameras on one cable depends on the type of camera. An analog coax camera needs its own cable all the way back to the DVR, so there is no practical way to put two of them on one coax run. Network (IP) cameras are different: you can run one network cable to the far end of the building, put a small switch there, and connect two or more cameras to that switch. It works well, as long as the cable can carry enough power for every camera and enough bandwidth for every video stream.

This guide explains how to tell which situation you are in, which hardware to use at the far end, the two numbers you need to check, and what each symptom means if something goes wrong afterwards.

First: find out which kind of cameras you have

Look at the plug on the camera's cable tail.

• A round BNC plug and a small DC power plug means an analog camera (CVBS, TVI or a similar format) that records to a DVR over coax. Each camera sends its own video signal down its own cable. Two cameras cannot share one coax run.
• A square network plug (RJ45), often with a DC plug next to it, means a network camera. These send digital data, and many cameras can share one network link through a switch, the same way computers in an office share one connection.

If you are not sure, the label on the camera or its box usually names the type, and our guide to IP network cameras versus analog CCTV explains the differences in more detail. The rest of this article is mostly about network cameras, because that is where one cable really can serve several cameras.

Why coax is one camera per cable

An analog camera puts one continuous video signal on the coax. The DVR has one input per camera, and each input expects exactly one signal. There is no addressing, so if you joined two cameras onto one coax with a splitter, the two signals would simply interfere with each other and you would see a broken picture or nothing at all.

What people with coax systems do instead:

1. Pull extra cables along the same route. If you already have one coax to a spot, a second run can often follow the same path, in the same conduit or clips. A multi-cable siamese bundle is one tidy way to do this. Our coax and siamese cable installation guide covers the connectors and voltage drop.
2. Change that part of the system to network cameras. If pulling more cables is hard, switching the far-end cameras to IP lets one network cable serve several of them.
3. Reuse the coax as a network link. Adapters exist that send a network connection over an existing coax cable. With one of these at each end and a switch at the far end, an old coax run can feed several network cameras. Many of these adapters carry data only, so the far-end switch may still need a local power supply. Check the adapter documentation for power and speed before relying on this.

How one network cable feeds several IP cameras

The basic layout is simple:

Recorder or router → one long network cable → small switch at the far end → short cables → cameras.

The switch at the far end turns one connection into several. The recorder sees each camera as a separate device on the network, so each one is added, recorded and viewed on its own, exactly as if it had its own cable.

The part that needs thought is power. Each camera needs electricity, and there is usually no socket where the cameras are. That is where Power over Ethernet (PoE) comes in. If you are new to PoE, read the PoE camera setup guide first; it covers switches, NVRs and cable choice for the normal one-cable-per-camera setup.

Option A: a PoE-powered switch at the far end

This is the neatest way to run 2 PoE cameras on one cable. You use a small switch that is itself powered by PoE on its input port and passes PoE out to the cameras on its other ports. Depending on the seller these are called PoE passthrough switches, PoE extenders or PD-powered switches.

• The recorder's PoE port, or a PoE switch at the recorder end, powers the long cable.
• The far-end switch takes that power, keeps a little for itself, and shares the rest among the cameras.
• No socket is needed at the camera end.

The catch is that one cable can only bring a limited amount of power, and the far-end switch cannot give out more than it receives. This is the most common reason these setups fail.

Option B: a normal switch with a local power supply

If there is a mains socket near the cameras, you can use an ordinary PoE switch powered from that socket. The long cable then only carries data, and the local switch supplies power to the cameras. This removes the power limit of the single cable, but it means the cameras stop when that local socket loses power, so plan any backup power at both ends.

Option C: passive cable-sharing adapters

You may see small adapters that split the four pairs inside one network cable into two separate connections. They can work for two cameras on low-speed links, but they generally do not pass standard PoE to both cameras, and they leave no spare capacity. Use them only if the adapter's documentation clearly says it supports your setup, including power.

The two numbers you must check

Number 1: power

Read the maximum power draw for each camera from its label or manual. Use the maximum, not the typical figure, because most cameras draw the most power at night when the infrared lights are on. Then check what the far-end switch can deliver in total on its output ports, which depends on the kind of PoE coming into it.

A worked example with assumed figures: suppose your manual says each camera can draw up to 5 watts, and the far-end switch's spec sheet says that, when fed from a standard PoE port, it can supply up to 12 watts in total to its outputs. Two cameras at 10 watts fit with some margin. Three cameras at 15 watts do not, and one of them will likely shut off or reboot at dusk. Your real figures will be different, so read them from your own camera and switch documentation, not from this example.

If the budget is tight, power the long cable from a higher-power PoE source if your switch supports it, reduce the number of cameras on that run, or switch to Option B.

Number 2: bandwidth

All the cameras behind the far-end switch share one link back to the recorder. Each camera's video stream uses part of that link, and their bitrates add up.

A worked example with assumed figures: if each camera's main stream is set to around 4 megabits per second, two cameras need about 8, plus a little for the sub-stream used when you watch on a phone. That is small compared with a typical wired network link, so two or three cameras rarely cause trouble. Problems usually appear only with many cameras, very high resolution settings, or a link that has dropped to a lower speed because of a poor cable or bad termination. You can see or change each camera's bitrate in its video settings in the app or on the recorder; the menu name varies by model and app version.

Step by step: putting two or more PoE cameras on one cable

1. Count the cameras and list their maximum power draw. Write down the model and maximum wattage of each.
2. Choose the far-end switch. Check that it can be powered by PoE on its input port, how many PoE output ports it has, and its total output budget for your type of input power.
3. Check the cable length. Each network cable segment has a length limit, commonly quoted as around 100 metres. Measure the long run, and remember the short cables from the switch to the cameras are separate segments. Check your switch documentation for its own limits.
4. Use proper cable. Solid copper network cable, outdoor-rated if any part runs outside. Avoid cheap copper-clad cable for PoE, because it loses more power and runs warmer.
5. Bench test everything first. Before drilling anything, connect the recorder, the long cable (or a spare cable of similar length), the far-end switch and all the cameras on a table. Check that every camera powers up and shows live video at the same time.
6. Add the cameras. Many recorders add cameras automatically only when they are plugged into the recorder's own PoE ports. Cameras behind an extra switch often have to be added by searching the network from the recorder menu or by adding them in the app. Name each camera by location as you go.
7. Test at night. Cover the light sensor or wait for dusk so the infrared lights come on. This is the moment of highest power draw, and it is when an overloaded switch shows itself.
8. Mount the switch in a protected place. Indoors, in a ceiling space or a weatherproof box, not loose outside. Leave a label on it so nobody unplugs it later thinking it is unused.
9. Mount, aim and seal the cameras, then check live view and a recording playback for every camera from your phone.

Ladder and roof work is dangerous: work with a second person, and switch off power before working near any mains wiring. If your plan needs a new socket for Option B, use a qualified electrician.

What each symptom usually means

• One camera goes offline or reboots every evening: the power budget is exceeded when the infrared lights switch on. Check the maximum draw again, or move one camera to another run.
• None of the far-end cameras power up: the far-end switch is not receiving enough power, or its input port is not the one marked for PoE input. Check which port is the input and what type of PoE it expects.
• All cameras on the run freeze or lag together: usually a weak link on the long cable, such as a poor crimp or a damaged section, which can make the link fall back to a lower speed. Re-terminate the ends and test the cable.
• Cameras power on but the recorder does not show them: the recorder may not add cameras on an external switch automatically. Search the network from the recorder or add them in the app.
• Everything worked until it rained: water in a connector or the switch box. Seal the connections and move the switch somewhere dry.

If you are still deciding whether cable is worth it at all for a particular spot, our comparison of hard wired versus WiFi security cameras may help, since a WiFi camera with a local power socket is sometimes simpler for one isolated location.

When to get help

Get help from a professional installer if the long cable has to go through walls with mains wiring, across a roof, or underground between buildings, or if you need a new power point. Also ask for help if cameras keep dropping after you have checked the power budget and re-terminated the cable, because a cable tester can show faults that are invisible by eye. For questions about a specific camera's power draw or supported settings, check its manual or contact the seller with the model number from the label.

Install or resell cameras?

If you fit systems for customers, sharing one cable is a useful way to cover a gate, a side yard or a second building without pulling several runs, but quote it carefully. Use the cameras' maximum power draw and the far-end switch's real output budget, and leave headroom so the job does not come back on the first cold night. Put the far-end switch in a labelled, protected box, and note on the handover sheet which cameras depend on that one cable, so the customer knows a single fault there affects all of them. Bench test the full chain with the exact switch model before you leave the shop. If you install or sell security cameras and want to talk about supply and dealer terms, see the Yoosee partner information.

Frequently asked questions

Can I use a simple cable splitter to connect two cameras to one network cable?

Only if its documentation says it supports your cameras, including power. A switch is the safer choice because it handles power properly and leaves a free port for another camera later.

If one camera fails, do the other cameras on the same cable stop too?

Normally no. Each camera has its own port on the far-end switch, so one faulty camera only affects itself. But if the long cable or the far-end switch fails, every camera behind it goes offline, so protect that switch and its connections well.

Can I add more cameras later to the same cable?

Yes, if the far-end switch has free ports and there is spare power and bandwidth. Recalculate the power budget with the new camera's maximum draw included, then bench test before mounting it.

Does the recorder count cameras on a shared cable differently?

No. The recorder sees each network camera as a separate device, so every camera still uses one of the recorder's channels. Check how many channels your recorder supports before adding cameras.

Can two analog cameras share one coax cable if I use a video splitter?

No. A video splitter sends one camera's signal to two places; it cannot merge two cameras into one cable. If pulling another coax run is not practical, a coax network adapter or a move to network cameras is the usual way round it.