A cable that happily runs a PC can still fail a PoE camera, because power exposes faults that data alone tolerates. Mode B power uses the pairs 100 Mbps ignores - so your testing and cable choice both have to change.
Technical AnshuPoECCTV Camera
Watch the full RJ45 crimping guide on video - every step shown live, from stripping the cable to the final tester check
CCTV installs generate the strangest callbacks in networking: the camera that reboots only at night, the access point that works on the bench and dies on the ceiling. Nine times out of ten it is the cable, and specifically what PoE asks of it.
PoE Power Pairs - What Must Be Perfect (Reference)
Pin 1White-Orange
Pin 2Orange
Pin 3White-Green
Pin 4Blue
Pin 5White-Blue
Pin 6Green
Pin 7White-Brown
Pin 8Brown
Straight-through T568B both ends. 802.3af Mode A powers pins 1-2 and 3-6 with data; Mode B powers the spare pairs, pins 4-5 and 7-8. Every pair must be continuous.
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One Cable Carries Both Data and Power
Power over Ethernet sends DC power down the same cable as data. In Mode A, power rides the data pairs (pins 1-2 and 3-6). In Mode B, power rides the spare pairs (pins 4-5 and 7-8) - the very pairs that 100 Mbps data ignores. Modern switches and cameras negotiate what they need. Your job is simpler: all eight wires perfect, because you do not get to choose which pairs the equipment uses.
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Crimp a Camera Cable Step by Step
Use straight-through T568B at both ends - never a crossover for cameras, NVRs or access points
Prefer a factory patch lead for short camera tails, or terminate the solid run cable at a jack and patch from there. Field plugs on solid outdoor cable are a known weak point
Keep connector and boot rated for the location; a dab of protection beats a corroded contact in three months
Test all eight wires, then test with a real PoE load - plug the camera in and confirm it boots fully, including IR lights at night if it has them
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PoE Faults That Disguise Themselves
Camera works all day, reboots at night - IR LEDs switch on, current rises, and a high-resistance run (CCA, long, or a poor crimp) drops the voltage below the camera's limit. Classic voltage-drop signature
Camera powers but shows no network - power pairs fine, data pairs faulty. Or the reverse: network link at a desk test, no power in the field (Mode B pairs open)
Works on a 3 m test lead, fails on the installed run - length plus conductor quality. PoE budgets are honest physics: 802.3af delivers 15.4 W at the switch and guarantees only 12.95 W at the device after cable loss
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Cable Choice Rules for PoE
Pure copper, always. CCA plus PoE is the single most common cause of mystery camera reboots
Respect the 100 m channel limit even more strictly under PoE load - resistance is the enemy
For long or hot runs, Cat6 pure copper gives lower resistance headroom than thin Cat5e
Honest note: passive PoE injectors (non-standard, fixed 24 V or 48 V) are not the same as 802.3af/at. They push power without negotiation and can damage non-PoE devices. Match the injector to the camera spec, and label passive-PoE cables so nobody plugs one into a laptop.
Watch the Full RJ45 Crimping Video
See the crimping technique live on camera - wire order, seating depth and tester reading, exactly as done in this guide.
Will a cable with one broken spare pair still run a PoE camera?
Not reliably. If the switch and camera negotiate Mode B, the spare pairs (pins 4-5 and 7-8) carry the power, so one open wire means no power at all. Mode A devices may work, but never sign off a PoE run with a known faulty pair - the next device plugged in may need it.
How far can I run a PoE camera?
The same 100 m channel limit applies, and under PoE the practical limit is stricter because resistance steals voltage. With pure copper Cat5e or Cat6, runs to about 90 m are routine. With CCA, cameras can fail at 40 m. If the camera reboots when its IR lights come on, voltage drop is the prime suspect.
Is Cat6 required for PoE?
No - 802.3af and at run fine on good Cat5e. Cat6 pure copper helps on long or high-power runs because its thicker conductors have lower resistance. What is required is real copper; category matters less than material.
This guide is based on the Technical Anshu RJ45 crimping video • Stuck on any step? Ask in the video comments - you will get a reply there