Will the cable run power my camera?
Before you buy cable, check that a camera will actually work at the far end of it. For PoE cameras we check the 100m length limit and the power the camera needs. For 12V cameras we calculate the voltage lost on the way. If a run won’t work, we’ll tell you what to change.
Will it work?
Good to go
PoE over 30 m of cable
- 30m is fine: network cable can go up to 100m.
- This 6W camera is inside the 802.3af (PoE) limit of 12.95W, with 6.9W to spare.
- Check the switch as a whole too: lots of 8-port switches can’t power eight cameras at full draw all at once.
PoE switches we sell
Browse networking- 4 portsGoodTop PoE-Extender-Repeater-4-Port-Gigabit-1000M 4 Port PoE Repeater for Cameras, 1000M£16.93
- 8 portsUKVISION UK-SW-8-100-P 8-Port PoE Switch, 100Mbps, 65W Budget, 2 Uplinks, 250m Extend Mode£31.87
- 9 portsHikvision DS-3E0109P-E/M 9-Port PoE Switch, 8 PoE Ports at 100Mbps, 300m Long Range£65.48
- 16 portsUKVISION UK-SW-16-1000-P 16-Port Gigabit PoE Switch, 2 Gigabit Uplinks, 150W Budget£78.00
- 24 portsUKVISION UK-SW-24-1000-P 24-Port Gigabit PoE Switch, 150W Budget, 2 Uplinks, 250m£113.44
Counting ports is the easy bit. What matters more is the switch’s total PoE budget: add up what your cameras need and make sure it fits.
How it works, simply
A PoE camera can be up to 100m from the switch, using Cat5e or Cat6 cable. The PoE standard decides how much power each camera can have: 12.95W with 802.3af, 25.5W with 802.3at and 51W with 802.3bt. Usually it’s the switch, not a single camera, that runs short. Add together what every camera needs and check the total fits within the switch’s overall PoE budget; the figure for one port on its own isn’t enough to go on.
On 12V power, the cable itself loses some voltage, because the current makes the trip out and back. A run twice as long loses twice as much, and a cable one size thicker halves the loss. Most cameras still work at around 10.8V, about 10% below 12V. At night, though, the infrared lights come on and can double what a camera uses, so cameras that work perfectly at 3pm can drop out at midnight. If yours won’t work, you can move that camera to PoE, use 24V equipment, fit thicker cable, or add a power supply right by the camera.
