Which UTP cable to choose for PoE and IP cameras: category, copper, AWG and line length

Short answer: what matters more than the category

For stable PoE power supply to an IP camera, the key parameter is not the cable category but the resistance of the conductor. The camera draws current, and the higher the line resistance, the greater the voltage drop and heating. A cable with copper conductors AWG23 (diameter 0.573 mm) has a resistance of about 6.7 ohms per 100 meters of a single conductor, AWG24 (0.511 mm) — about 8.4 ohms. Copper-clad aluminum (CCA) at the same diameter provides resistance approximately 55% higher than copper and is not suitable for PoE.

Cat5e with copper conductors AWG24 is sufficient for most IP cameras on lines up to 80–90 meters at power up to 30 W (PoE+). For powerful PTZ cameras, lines longer than 80 meters, or PoE++ power (60–100 W), Cat6 with AWG23 conductors is used. The specific choice is determined by camera power, route length, and PoE standard.

PoE standards and camera power

The IEEE 802.3af standard (PoE) provides up to 15.4 W per power sourcing equipment port and up to 12.95 W at the device. Current — up to 350 mA per pair. This is sufficient for most dome IP cameras without heating. The IEEE 802.3at standard (PoE+) raises power to 30 W per source port and 25.5 W at the device, current — up to 600 mA per pair. PoE+ is necessary for cameras with IR illumination, heating, or a motorized lens.

The IEEE 802.3bt standard (PoE++ / 4PPoE) exists in two types. Type 3 provides up to 60 W per source port and 51 W at the device, Type 4 — up to 100 W per source port and 71.3 W at the device. Current in Type 4 reaches 860 mA per pair when using all four pairs. PoE++ is used for powerful PTZ cameras with heating, multifunctional cameras, and devices with heating in cold climates.

The maximum channel length for all PoE standards is 100 meters. This limitation includes patch cords at both ends. The permanent link (cable in the wall) must not exceed 90 meters. If the camera reboots when IR illumination turns on, this is a sign of insufficient voltage at the device. The cause is excessive voltage drop due to high line resistance or too long a route.

Cat5e or Cat6 for IP cameras

Cat5e is certified for frequencies up to 100 MHz and transmits 1 Gbit/s over the full length of 100 meters. For a 4K IP camera with a bitrate of 8–16 Mbit/s, Cat5e bandwidth is more than sufficient. The camera does not use even a tenth of the gigabit channel. The advantage of Cat6 is lower attenuation and better interference immunity due to the central pair separator. For lines in conditions of electromagnetic interference, Cat6 is preferable.

For PoE, what matters more is not the category but the conductor cross-section. Cat6 is more often produced with AWG23 conductors, Cat5e — with AWG24. A thicker conductor reduces voltage drop and heating. If you are choosing between Cat5e AWG24 and Cat6 AWG23 for a long line or a powerful camera, Cat6 with AWG23 will give the best result. A basic comparison of categories is covered in the material UTP Cat5e or Cat6: which to choose.

Copper Cu vs CCA

Copper-clad aluminum (CCA, Copper Clad Aluminium) is an aluminum core with a thin copper coating. The resistivity of copper is 0.01724 ohm·mm²/m, aluminum — about 0.028 ohm·mm²/m. The linear resistance of an AWG24 copper conductor is about 0.188 ohm/m, of CCA — 0.280–0.330 ohm/m. The difference of 1.5–1.7 times directly affects voltage drop and heating under PoE.

At the same current, CCA heats up faster and more strongly than copper. Studies show that the initial temperature rise in CCA can be twice as high as in a copper conductor at the same current. This creates a risk of overheating and insulation damage. PoE equipment manufacturers do not recommend CCA. For PoE+ and PoE++, CCA cable is prohibited. Copper cable provides stable power, lower voltage drop, and a service life of more than 25 years. A detailed comparison is in the material UTP copper or copper-clad CCA: which to choose.

AWG23 vs AWG24

AWG (American Wire Gauge) is an American system for marking wire diameter. The smaller the number, the thicker the conductor. AWG23 — diameter 0.573 mm, cross-sectional area 0.258 mm². AWG24 — diameter 0.511 mm, area 0.205 mm². The difference in cross-section is about 26%. The resistance of a single AWG23 conductor per 100 meters is about 6.7 ohms, AWG24 — about 8.4 ohms. The loop resistance of a pair (two conductors) per 100 meters: AWG23 — about 13.4 ohms, AWG24 — about 16.8 ohms.

For PoE, this means that on a 100-meter line with a 25 W camera (current about 0.5 A), the voltage drop across the AWG24 loop will be about 8.4 V, across AWG23 — about 6.7 V. At 48 V at the source, 39.6 V will reach the camera with AWG24 and 41.3 V with AWG23. A camera with an operating range of 44–57 V may not start on AWG24. AWG23 provides margin. For PoE++ with current up to 0.86 A, the difference is even more significant. The choice between AWG23 and AWG24 is covered in the material AWG23 or AWG24: which twisted pair gauge to choose.

Effect of line length on power

The voltage drop on a line is proportional to length and conductor resistance. Formula: ΔU = I × R_loop × L, where I is current, A; R_loop is the loop resistance of the pair, ohm/m; L is line length, m. For AWG24 cable, R_loop ≈ 0.168 ohm/m, for AWG23 — ≈ 0.134 ohm/m.

Example calculation for a 25 W camera (PoE+, current 0.5 A):

• Line 50 m, AWG24: ΔU = 0.5 × 0.168 × 50 = 4.2 V. Voltage at the camera: 48 − 4.2 = 43.8 V.
• Line 100 m, AWG24: ΔU = 0.5 × 0.168 × 100 = 8.4 V. Voltage at the camera: 48 − 8.4 = 39.6 V.
• Line 100 m, AWG23: ΔU = 0.5 × 0.134 × 100 = 6.7 V. Voltage at the camera: 48 − 6.7 = 41.3 V.

The IEEE 802.3at standard requires that the voltage at the device be at least 42.5 V for PoE+ and 41.1 V for PoE. At 39.6 V, the camera may operate unstable or reboot when IR illumination turns on. For long lines and powerful cameras, a voltage drop margin is necessary. This is the main reason why AWG23 and copper conductors are chosen for PoE. Installation rules and length limitations are described in the material UTP cable installation: standards for indoor, outdoor, in-ground, and on messenger wire.

Table: scenarios and recommended cable

In all scenarios, only copper cable is used. CCA is not recommended for PoE and is prohibited for PoE+ and PoE++. Outdoor cable is selected according to installation conditions: UTP indoor or outdoor.

Practical examples

Example 1. Short line to the camera.

Dome IP camera 12 W (PoE, current 0.25 A), line 30 m. Voltage drop calculation for AWG24: ΔU = 0.25 × 0.168 × 30 = 1.26 V. Voltage at the camera: 48 − 1.26 = 46.7 V. Margin is sufficient. Cat5e AWG24 is suitable. The cable is installed indoors, indoor sheath.

Example 2. Long route.

Outdoor camera 25 W (PoE+, current 0.5 A), line 90 m. For AWG24: ΔU = 0.5 × 0.168 × 90 = 7.56 V, voltage 40.4 V — below the minimum of 42.5 V. For AWG23: ΔU = 0.5 × 0.134 × 90 = 6.03 V, voltage 41.97 V — at the limit. AWG23 cable and margin are required. Cat6 AWG23 outdoor is used.

Example 3. Powerful PTZ camera.

PTZ camera 60 W (PoE++ Type 3, current 0.86 A at 48 V), line 60 m. For AWG23: ΔU = 0.86 × 0.134 × 60 = 6.9 V, voltage 41.1 V — minimum allowable for PoE. Margin is necessary: reduce length or use cable with even lower resistance. Cat6 AWG23 is used, the line is shortened to 50 m, or an intermediate switch is used.

Example 4. Outdoor camera on the street.

Camera 15 W (PoE), line 40 m, installation along the facade. Cat5e AWG23 outdoor with black polyethylene sheath and hydrophobic filling is used. Calculation: ΔU = 0.35 × 0.134 × 40 = 1.88 V, voltage 46.1 V. Margin is sufficient. Indoor cable is not suitable for outdoor use.

Choosing cable for outdoor cameras

For outdoor installation, cable in outdoor design with a black polyethylene sheath resistant to ultraviolet is used. An indoor sheath made of PVC or LSZH deteriorates under the sun within one or two seasons. Outdoor cable often has hydrophobic filling that prevents moisture propagation along the cable when the sheath is damaged. For installation on poles and suspension, cable with a built-in messenger wire is used.

For outdoor cameras in conditions of lightning surges and electromagnetic interference, shielded FTP or STP cable is used. Shielding protects the line from interference and reduces the risk of equipment damage during discharges. When choosing between UTP and FTP for outdoor use, installation conditions are taken into account: UTP or FTP: which twisted pair cable to choose. A general guide to types and characteristics of twisted pair is given in the material UTP cable: types, characteristics, and selection.

Common mistakes

Using CCA for long PoE. CCA cable has resistance 55% higher than copper. On a long line, the voltage drop exceeds the allowable value, the camera does not receive the required power and reboots. For PoE+ and PoE++, CCA is prohibited.

Too thin conductor (AWG24) for a powerful camera. For a PTZ camera with heating or a camera with powerful IR illumination, the current reaches 0.6–0.86 A. On AWG24, the voltage drop exceeds the allowable value, the camera operates unstable. AWG23 or shortening the line is required.

Incorrect outdoor sheath. Indoor cable with PVC sheath installed outdoors deteriorates under ultraviolet and moisture. After one or two seasons, the sheath cracks, insulation is exposed, and the line fails. For outdoor use, outdoor cable with black polyethylene is used.

Line without voltage drop margin. Calculation based on nominal current without margin leads to the fact that at peak load (IR illumination turning on, heater operation), the voltage at the camera drops below the minimum. The camera reboots. A margin of 5–10% in voltage must be included.

Ignoring the 100-meter length limit. An Ethernet channel, including patch cords, must not exceed 100 meters. If the permanent link is 90 meters and patch cords are 5 meters at each end, the total length is 100 meters. Exceeding this leads to packet loss and unstable operation.

FAQ

Can Cat5e be used for a PoE camera?

Yes, Cat5e with copper conductors is suitable for most IP cameras up to 25–30 W on lines up to 80 meters. For powerful cameras and long routes, Cat6 with AWG23 conductors is preferable. The main thing is copper conductors, not CCA.

Why does the camera reboot when IR illumination turns on?

When IR illumination turns on, the camera’s current consumption increases sharply. If the line resistance is high (CCA, thin AWG24 conductor, long length), the voltage drop increases, and the voltage at the camera drops below the minimum. The camera reboots. The solution is cable with copper AWG23 conductors, shortening the line, or replacing with a more powerful PoE source.

Is AWG24 sufficient for PoE+ over 100 meters?

For PoE+ with current up to 0.5 A over a 100-meter line, AWG24 gives a voltage drop of about 8.4 V. The voltage at the camera is 39.6 V — below the minimum of 42.5 V. The camera may not start. For PoE+ over 100 meters, AWG23 is used.

Is shielded cable needed for an outdoor camera?

For outdoor use, shielded FTP or STP cable is recommended. Shielding protects against lightning surges and electromagnetic interference. If the camera is installed away from interference sources and lightning activity is low, UTP outdoor can be used. For hazardous areas, requirements are separate.

Which cable to choose for a PTZ camera with heating?

For a PTZ camera with heating of 60 W and above, Cat6 with copper AWG23 conductors is used. Current can reach 0.86 A. On a line up to 50 meters, AWG23 provides acceptable voltage drop. For lines more than 50 meters, an intermediate switch or shortening the route is recommended.

Sources

• IEEE 802.3af-2003 “Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications — Amendment: Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI)” — current — IEEE — PoE standard, power 15.4 W, current 350 mA.
• IEEE 802.3at-2009 “Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications — Amendment 3: Data Terminal Equipment (DTE) Power via the Media Dependent Interface (MDI) Enhancements” — current — IEEE — PoE+ standard, power 30 W, current 600 mA.
• IEEE 802.3bt-2018 “IEEE Standard for Ethernet — Amendment 2: Physical Layer and Management Parameters for Power over Ethernet over 4 pairs” — current — IEEE — PoE++ standard, Type 3 and Type 4, power 60 and 100 W, current up to 860 mA.
• Fluke Networks. “Tips to Identify Copper Clad Aluminium (CCA) Cables” — technical article — flukenetworks.com — aluminum resistance 55% higher than copper, CCA heating under PoE.
• Siemon. “The Impact of Copper Clad Aluminium (CCA) Conductors in Balanced Pair Cables” — technical report — siemon.com — temperature rise in CCA is twice as high as in copper at the same current.
• Trassir. “Cabling Recommendations for PoE” — technical guide — confluence.trassir.com — recommendations: Cat5e minimum, Cat6 preferred, length up to 80 m, copper conductors only, for outdoor — HDPE.
• ANSI/TIA-568.2-D “Balanced Twisted-Pair Telecommunications Cabling and Components Standard” — current — TIA TR-42 committee — channel length limit 100 m, permanent link 90 m.
• KazKabel. “UTP copper or copper-clad CCA: which to choose” — practical guide — kazkabel.kz — comparison of copper and CCA, resistance, heating, application.
• KazKabel. “AWG23 or AWG24: which twisted pair gauge to choose” — technical article — kazkabel.kz — diameter, cross-section, resistance of AWG23 and AWG24.
• KazKabel. “UTP Cat5e or Cat6: which to choose” — technical article — kazkabel.kz — differences between categories, frequency range, speed.
• KazKabel. “UTP indoor or outdoor: which cable is needed for outdoor and home” — practical guide — kazkabel.kz — choosing sheath for outdoor installation.
• KazKabel. “UTP cable: types, characteristics, and selection” — complete guide — kazkabel.kz — construction, categories, regulatory framework.