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PoE for CCTV: power budget, cable length and switch guide

4 min read
Short answer: Add up the maximum power of every camera, add about 20%, and choose a PoE switch whose total power budget is at least that figure. Keep every cable run under 100 m, use pure-copper Cat6 (never copper-clad aluminium), and put the switch and the recorder on a UPS. Most fixed cameras need PoE (15.4 W) or PoE+ (30 W); large PTZ cameras with heaters may need PoE++ (60 W).

Power over Ethernet (PoE) lets one network cable carry both data and power to an IP camera, so there is no separate power point at the camera. It makes installation cleaner, but only if the switch, the cable and the camera power draw are planned together. This is the checklist we use.

PoE standards at a glance

Standard Common name Power at the switch port Power available to the camera
IEEE 802.3af PoE 15.4 W 12.95 W
IEEE 802.3at PoE+ 30 W 25.5 W
IEEE 802.3bt Type 3 PoE++ (60 W) 60 W 51 W
IEEE 802.3bt Type 4 PoE++ (90 W) 90 W 71.3 W

The camera receives less than the port supplies because some power is lost in the cable. Read the camera datasheet for its maximum consumption, including infrared lights and heater, and match it to the standard.

What cameras typically draw

  • Fixed indoor dome or turret: about 4 to 8 W.
  • Outdoor bullet with infrared: about 7 to 13 W.
  • 360° fisheye: about 8 to 15 W.
  • PTZ: about 20 to 30 W, and more with a heater or wiper in the cold or in a harsh outdoor position.

These are typical planning figures. Always use the datasheet value for the model you buy.

Calculate the switch power budget

A switch has a total PoE budget that is often lower than the number of ports multiplied by the per-port maximum. A 24-port switch with 30 W ports may still have a 250 W total budget. Add up the real camera load, not the port count.

Cameras Power each Subtotal
12 fixed cameras 8 W 96 W
2 PTZ cameras 25 W 50 W
2 fisheye cameras 12 W 24 W
Total 170 W

Add 20% for headroom and future cameras: 170 W × 1.2 = 204 W. Choose a switch with a PoE budget of at least 210 W; a 250 W model leaves room to grow.

Cable: the 100 metre rule and what to avoid

  • Maximum length: Ethernet allows 100 m for the whole channel, which is 90 m of fixed cable plus patch leads.
  • Use pure copper. Copper-clad aluminium (CCA) cable is cheaper but has higher resistance, so it loses more power, runs hotter and often fails at length. Choose solid pure-copper Cat6.
  • Beyond 100 m: use a PoE extender, or run fibre to a second switch near the cameras and power that switch locally. PoE does not pass over fibre.
  • Outdoors: use outdoor-rated cable, weatherproof connectors and proper grounding. Add surge protection where cables enter or leave a building.

Network bandwidth

Each camera sends a continuous stream to the recorder. Sixteen cameras at 4 Mbps send about 64 Mbps, and 32 cameras at 8 Mbps send about 256 Mbps. A gigabit uplink from the camera switch to the recorder is normally enough for these systems; larger systems may need several uplinks or a faster link. Keep cameras and recorders on their own VLAN so office and guest traffic cannot affect recording.

Power cuts and the recorder

If the PoE switch loses power, every camera stops. Put the PoE switch, the recorder and the router on a UPS sized for the total load and for the minutes you need, and consider a generator or longer-runtime battery for critical sites.

Common mistakes

  • Buying a switch by port count instead of by total PoE budget.
  • Using CCA cable, or exceeding 100 m.
  • Forgetting that PTZ and heated cameras need PoE+ or PoE++.
  • Daisy-chaining small switches so that one uplink carries every camera.
  • Leaving the recorder and switch without a UPS.
  • Mixing CCTV with the office network instead of using a separate VLAN.

Frequently asked questions

Can I use any PoE switch with any IP camera?

Usually yes, if the switch supports the standard the camera needs (af, at or bt) and has enough total power budget. Check both the per-port power and the total.

How far can a PoE camera be from the switch?

Up to 100 m on Cat5e or Cat6 copper. For longer distances use a PoE extender or a fibre link to a second switch.

Is Cat6 necessary for CCTV?

Cat5e can carry PoE and the data of most cameras, but Cat6 is the better choice for new installations because it leaves room for higher-resolution cameras and gives a cleaner installation. Pure copper matters more than the category.

Do I need a managed switch?

For more than a handful of cameras, yes. A managed switch gives you VLANs, PoE monitoring and the ability to restart a camera port remotely.

Next step: our engineers include the switch, cabling and UPS in every CCTV quotation. See also enterprise networking, fibre and structured cabling and the guide How to choose a CCTV system.