PoE Cable Voltage Drop Calculator

Calculate PoE Cat6, Cat5e, and CCA cable voltage drop, delivered terminal voltage, safe run distances, and night-time infrared reboot risks.

Input Parameters

Try Example:

Calculation Results

cableLenM: 65
cableType: cat6
camPowerWatt: 8
sourceVoltage: 48
loopResistancePer100m: 14
totalResistanceOhm: 9.1
currentAmpere: 0.1667
voltageDrop: 1.52
endVoltage: 46.48
percentageDrop: 3.2
powerLossWatt: 0.25
cableStatus: AMAN (Standar IEEE 802.3af/at)
cableStatusEn: SAFE (Complies with IEEE 802.3af/at)
cableWarning: Tegangan di ujung kamera sangat stabil.
cableWarningEn: Voltage delivered at device endpoint is highly stable.
summaryText: Ringkasan Jatuh Tegangan (Voltage Drop) Kabel PoE – InfraCalc.id Tipe Kabel : CAT6 (Hambatan Loop: 14 Ω / 100m) Panjang Tarikan : 65 meter (Total Hambatan: 9.1 Ω) Daya Beban : 8 Watt @ Sumber 48V DC (Arus: 0.1667 A) Voltage Drop : 1.52 V (3.2%) Tegangan Ujung : 46.48 V DC (Rugi Daya: 0.25 W) Status Kelayakan: AMAN (Standar IEEE 802.3af/at) Rekomendasi : Tegangan di ujung kamera sangat stabil.

How to Use This Tool

Enter the physical cable run length from the PoE switch to the camera endpoint in meters.
Select the cable conductor category (Cat6 Pure Copper, Cat5e Pure Copper, or Copper-Clad Aluminum CCA).
Specify maximum camera power consumption with IR illuminated (Watts) and review delivered terminal voltage.

Worked Example: Standard 65m Cat6 Run 8W Camera

Worked example: A 65m CAT6 cable run for an 8W device powered from a 48V PSE yields a loop resistance of 9.1 Ω and a voltage drop of 1.52V (3.2%). Delivered terminal voltage is 46.48V DC (Status: SAFE (Complies with IEEE 802.3af/at)).

Example Input

{
  "cableLenM": 65,
  "cableType": "cat6",
  "camPowerWatt": 8,
  "sourceVoltage": 48
}

Calculated Output

cableLenM:: 65
cableType:: cat6
camPowerWatt:: 8
sourceVoltage:: 48
loopResistancePer100m:: 14
totalResistanceOhm:: 9.1
currentAmpere:: 0.1667
voltageDrop:: 1.52
endVoltage:: 46.48
percentageDrop:: 3.2
powerLossWatt:: 0.25
cableStatus:: AMAN (Standar IEEE 802.3af/at)
cableStatusEn:: SAFE (Complies with IEEE 802.3af/at)
cableWarning:: Tegangan di ujung kamera sangat stabil.
cableWarningEn:: Voltage delivered at device endpoint is highly stable.
summaryText:: Ringkasan Jatuh Tegangan (Voltage Drop) Kabel PoE – InfraCalc.id Tipe Kabel : CAT6 (Hambatan Loop: 14 Ω / 100m) Panjang Tarikan : 65 meter (Total Hambatan: 9.1 Ω) Daya Beban : 8 Watt @ Sumber 48V DC (Arus: 0.1667 A) Voltage Drop : 1.52 V (3.2%) Tegangan Ujung : 46.48 V DC (Rugi Daya: 0.25 W) Status Kelayakan: AMAN (Standar IEEE 802.3af/at) Rekomendasi : Tegangan di ujung kamera sangat stabil.

Core Concept & Engineering Notes

> [!WARNING] > **Standard Verification Notice (VERIFY)**: The DC loop resistance values applied by this calculator (Cat6: 14.0 Ω/100m, Cat5e: 18.8 Ω/100m, CCA: 32.0 Ω/100m) originate from the legacy codebase in tools-addons.js:820. These values retain a VERIFY flag and have not been independently cross-verified against official manufacturer cut-sheets or TIA/EIA-568 / ISO/IEC 11801 standards for 23/24 AWG solid conductors. Treat these results as indicative operational estimates and verify against manufacturer documentation for mission-critical engineering. Power over Ethernet (PoE) technology fundamentally streamlines enterprise network and surveillance infrastructure by delivering direct current (DC) electrical power alongside high-speed data packets over structured twisted-pair cabling. In operational deployments, however, the inherent electrical DC loop resistance of metallic conductors induces progressive voltage drop and thermal heat dissipation along the cable trajectory. As current flows from Power Sourcing Equipment (PSE)—such as managed PoE network switches—toward remote Powered Devices (PD) including IP surveillance cameras and outdoor wireless Access Points, a portion of the nominal voltage drops per Ohm's Law (V = I × R). Telecommunication standards such as IEEE 802.3af (PoE 15.4W) and IEEE 802.3at (PoE+ 30W) define 48V–54V DC source outputs while mandating delivered endpoint terminal voltages remain strictly above 37V to 42.5V DC thresholds. A rampant operational failure point stems from deploying budget Copper-Clad Aluminum (CCA) cabling instead of solid bare copper. CCA conductors exhibit a staggering DC loop resistance of 32 Ohms per 100 meters, exceeding Cat6 pure copper (14 Ohms per 100m) by more than 120%. While cameras drawing nominal 4–6 Watts during daylight may operate without obvious symptoms, nightfall triggers high-power infrared (IR) LED illumination (drawing 10–12W). The resulting current surge exacerbates voltage drop, plunging endpoint voltage below operating tolerances and triggering catastrophic reboot loops or video loss. This calculator validates run lengths, conductor metallurgy, and endpoint stability.

How It Was Calculated (Formulas & Steps)

Mathematical Formulas

Total Loop Resistance (Ω) = (Resistance per 100m × Run Length m) ÷ 100
Electrical Current (A) = Load Power Watts ÷ Source Voltage DC
Voltage Drop (V) = Current A × Total Resistance Ω
Terminal Endpoint Voltage (V) = Source Voltage - Voltage Drop
Percentage Drop (%) = (Voltage Drop ÷ Source Voltage) × 100
Thermal Power Dissipation (W) = Voltage Drop × Current A

Step-by-Step Calculation

1. Loop Resistance: CAT6 wire = 14 Ω / 100m -> R_total = (14 × 65) / 100 = 9.1 Ω
2. Load Current: I = P / V_source = 8 W / 48 V = 0.1667 A
3. Voltage Drop: V_drop = I × R_total = 0.1667 A × 9.1 Ω = 1.52 V (3.2% loss)
4. Endpoint Voltage Delivered: V_end = 48 V - 1.52 V = 46.48 V DC (Heat Dissipation = 0.25 W)
5. Compliance Assessment: SAFE (Complies with IEEE 802.3af/at). Recommendation: Voltage delivered at device endpoint is highly stable.

Frequently Asked Questions (FAQ)

Why do PoE CCTV cameras frequently reboot or drop offline specifically at night?

Nightfall triggers automatic infrared (IR) illuminators, surging camera power consumption 2 to 3 times higher. This elevated current doubles the voltage drop along the cable. On lengthy runs or sub-standard CCA cables, endpoint voltage drops below the camera's operational floor, triggering continuous reboot loops.

What is the maximum UTP cable distance for standard PoE without repeaters?

IEEE 802.3 Ethernet standards limit copper cable runs to 100 meters. Spans between 100m and 250m require toggling 'Extend Mode' on the PoE switch (throttling bandwidth to 10 Mbps) with solid Cat6 pure copper. Any distance beyond 250 meters mandates single-mode fiber optic cable.

What are the engineering hazards of using Copper-Clad Aluminum (CCA) cables?

CCA conductors feature a brittle aluminum core that easily fractures under pull tension and suffers over double the electrical resistance of pure copper. In addition to severe voltage drops, CCA cables generate dangerous resistive thermal heating when carrying higher PoE current loads, posing longevity and safety risks.

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References & Notes

Last updated: 2026-11-06Content Status: Draft (Pending Editorial Review)

Note: Results above are mathematical estimates based on standard formulas. Always verify against official vendor documentation and site conditions before production deployment.