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PoE Switch Budget

IEEE 802.3af / at / bt · Power Budget Verification

When to use: Verify a PoE switch's total power budget against the connected powered devices. The per-port figures (15.4 W af, 30 W at, 60/90 W bt) are the power sourced at the switch (PSE) and already include worst-case 100 m cable loss, so summing PSE watts gives the switch-side demand. Keep the total at or below the rated power budget with margin for simultaneous draw.

Switch

Total PoE Power BudgetFrom switch datasheet

Powered Devices

Class

Qty

360.0 W

Class

Qty

120.0 W

Class

Qty

92.4 W

✗ OVER BUDGET

572 W

of 370 W budget (155% used)

Results

Total Draw (PSE)572.4 W

Switch Budget370 W

Headroom-202.4 W

Utilization155%

PoE Ports Used20

Notes

PSE figures already include 100 m cable loss

PD actually receives ~12.95 W (af) / 25.5 W (at)

Keep ≥10% headroom for simultaneous peak draw

bt Type 4 (90 W PSE) drives ~71.3 W to the device