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PoE distance and budget calculator

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Check switch budget, per-port class limits, runs past 100 m, and voltage drop. Voltage at the device solves P = V·I − I²R.

Example plan Flag

364.8 W allocated of 370 W (98.6%). 5.2 W left. PD draw 308.4 W.

DeviceStandardPD max WAlloc WRun
Cam 1–12 × 12 802.3af Type 1 12.95 15.4 60 m OK
Cam 13–15 × 3 802.3at Type 2 25.5 30.0 85 m OK
Cam 16 × 1 802.3at Type 2 25.5 30.0 120 m Over 100 m
AP 1 × 1 802.3bt Type 3 51.0 60.0 40 m OK

Cam 16 at 120 m is past the 100 m channel limit.

Cam 16 voltage drop

25.5 W at the device, 50 V minimum at the switch, 120 m.

Loop resistance 7.9 Ω. Current 0.56 A. Voltage drop 4.4 V, so 45.6 V at the device. Cable loss 2.5 W.

IEEE 802.3 PoE reference

StandardTypePSE outPD maxMin VMax loop ΩPairs
802.3af115.4 W12.95 W44 V20.02
802.3at230.0 W25.5 W50 V12.52
802.3bt360.0 W51.0 W50 V6.254
802.3bt490.0 W71.3 W52 V6.254

100 m channel. Values from IEEE 802.3 tables via the Ethernet Alliance overview. Use the cable datasheet for exact ohms per meter. 23 AWG here is 0.066 Ω/m.

Planning aid only. Values are typical and vary by manufacturer, code edition and jurisdiction. Verify with manufacturer data, NEC/NFPA/TIA and the local AHJ. HireLV is not liable for designs based on these tools.