Cabling and PoE switches for IP cameras

Why one cable matters

A traditional camera needed two cables, one for video and one for power. Modern IP cameras can use a single network cable for both, a method called Power over Ethernet, or PoE. That one cable runs from a recorder or network switch to each camera.

This is a big reason that wired systems are generally seen as dependable. There is no battery to charge, no Wi-Fi signal to lose, and only one cable to install. The comparison with wireless is covered in wired PoE vs Wi-Fi cameras.

PoE basics

PoE sends low-voltage power along the same copper pairs that carry data. A camera that supports PoE draws what it needs from the cable. A source that provides the power is called power sourcing equipment: either a PoE switch, a PoE injector or an NVR with built-in PoE ports.

Three practical points follow.

• The camera must support PoE, or you need a separate splitter or power adapter.
• The source must supply enough power for every connected camera.
• The cable must be good enough to carry both power and data over the distance.

Common standards you will see are labelled 802.3af and 802.3at (sometimes called PoE+). The higher standard supplies more power per port, which matters for cameras with heaters, motorised lenses or strong infrared lights. The camera's specification states what it needs.

Cable types

IP cameras use twisted-pair network cable. The categories you will see are Cat5e and Cat6. Either is generally suitable for cameras at typical lengths, and Cat6 gives more headroom.

Other choices matter more than the category label.

• Copper conductors. Choose solid copper cable. Cheaper cable sold as copper-clad aluminium can have higher resistance, which reduces power delivery and can cause intermittent faults at longer distances.
• Outdoor rating. Cable exposed to sun and weather should be rated for outdoor or UV-resistant use, or run inside conduit.
• Shielded or unshielded. Unshielded is common. Shielded cable may help in places with heavy electrical interference, but it must be properly terminated.
• Quality of terminations. Poor connectors are a frequent cause of dropouts, regardless of cable category.

Cables should be run and labelled so each camera can be traced back to its port. Neat labelling saves time during faults.

The distance rule of thumb

The commonly quoted limit for Ethernet cable is about 100 metres from the switch or recorder to the camera. Treat that as a rule of thumb. It is a standard limit for copper network cable, not a guarantee that every camera will work at that distance.

Cable quality, power draw and joins all reduce the real figure. A long run to a power-hungry camera on poor cable may struggle well before 100 metres.

If a camera is further away, common options are:

• Place a second PoE switch nearer to the camera, linked back by a network cable or fibre.
• Use a PoE extender, which boosts the signal over longer distances.
• Run fibre between buildings or sheds and put a switch at the far end.

An installer will normally measure the actual cable route, which is almost always longer than a straight line across a plan.

Switch power budget

A PoE switch has a total power budget, the maximum watts it can supply across all ports at once. This is separate from the number of ports. A switch with eight ports does not necessarily have enough power for eight demanding cameras.

To check a budget:

1. List each camera's maximum power draw from its datasheet.
2. Add them together.
3. Compare the total with the switch's stated PoE budget.
4. Leave a margin. Running a switch right at its limit is asking for trouble.

For example, eight cameras that each draw up to 8 watts need around 64 watts. If the switch has a 60-watt budget, some cameras may fail to start or may drop out, even though there are enough ports.

Cameras with infrared lights and heaters draw more at night and in cold conditions, so check the maximum, not the average. The PoE budget tool lets you enter your cameras and compare the total with a switch.

Switch and recorder choices

• Recorder with built-in PoE ports. Simple for small systems, with cameras plugged straight into the back of the recorder. See NVR explained.
• Separate PoE switch. More flexible for larger sites or where cameras are spread over several areas.
• Unmanaged or managed. Unmanaged is simple. Managed switches give control over traffic and can help on larger networks, but need configuration.
• Uplink capacity. Many cameras sending high-resolution video add up. Make sure the link from the switch to the recorder can carry it. The bandwidth tool gives an estimate.

Installation checklist

• Measure real cable routes, not straight-line distances.
• Keep each run below roughly 100 metres.
• Use solid copper cable of suitable category.
• Use outdoor-rated cable or conduit outside.
• Keep data cables apart from mains wiring where possible.
• Confirm the total camera load against the switch budget with a margin.
• Label both ends of every cable.
• Test each run before closing the ceiling or wall.

Limits

This guide is general. Electrical work involving mains wiring needs a qualified person under the rules of your state, and that is separate from low-voltage network cabling. Check with your installer about which parts of a job are covered by which trade.

For a view on the cabling in a specific building, you can ask us about installation.

Frequently asked questions