What's the maximum PoE cable length for CCTV cameras?

IEEE 802.3 caps any Ethernet run at 100 m end-to-end (PHY layer). Standard PoE (Type 1, 15.4 W) typically works fine to ~90 m on Cat6 — beyond that voltage drop pushes the camera below the 37 V PD minimum. Higher-power Type 3/4 (60-90 W) drops the practical limit to ~60-70 m. Use a PoE extender or fiber for longer runs.

Should I use Cat5e, Cat6, or Cat6a for PoE cameras?

Cat5e (24 AWG) works for 4MP cameras on short runs — cheapest but highest voltage drop. Cat6 (23 AWG) is the mainstream choice — 40% less voltage drop, suitable for 8MP and full PoE+ at 90 m. Cat6a (23 AWG shielded) handles 10G future-proofing and 90 W Type 4 PoE at long runs — required for new commercial installs in many EU jurisdictions.

How do I calculate PoE voltage drop?

V_drop = I × R × L, where I = power ÷ 48 V, R = loop resistance per meter (Cat6 = 0.118 Ω/m), L = cable length. Example: 15.4 W camera at 100 m on Cat6 = (15.4/48) × 0.118 × 100 = 3.8 V drop — well within the 11 V budget. 90 W Type 4 at 100 m on Cat6 = 22 V drop — won't work, needs Cat6a or shorter run.

How much extra cable should I buy for slack?

Add 10% to total calculated length for slack: service loops at each end, mistakes during pull, and a re-terminate budget. For 800 m of camera runs, buy a 1000 m (3× 305 m) supply. Pulling cable twice is far more expensive than buying one extra reel — and unused Cat6 has resale value to other installers.

What if a single run exceeds 100 m?

Three options ranked by cost: 1) Move the camera (cheapest, usually feasible by 5-10 m). 2) PoE extender — typically €60-€150, repeats the signal and re-injects power. 3) Fiber media converter pair (€200-€400) — only option above ~200 m, also gives EMI immunity for industrial sites. Always preferred to route through a closer switch if available.