Just a selection of very quick and simple power consumption testing of various Juniper and Cisco devices to check the switch power usage.

Juniper EX4200-48T – No Ports Connected – 126w – Single PSU Connected
Juniper EX4200-48T – No Ports Connected – 150w – Dual PSU Connected
Juniper EX4200-48T – 48 RJ45 Ports Connected – 210w – Dual PSU Connected

Can therefore determine that the PSU in an EX4200 uses ~24w and that each RJ45 port uses ~1.25w each.

Juniper EX4300-48T – 48 1Gbe RJ45 Connected – 125w – Dual PSU Connected

Juniper QFX5100-48T – No Ports Connected – 170w – Single PSU Connected
Juniper QFX5100-48T – No Ports Connected – 180w – Dual PSU Connected
Each RJ45 port connected increases power consumption by ~2w.

Cisco Catalyst 2960-S-48 – No Ports Connected – 60w – Single PSU