hi,
the EX documentations seems to be clear here:
- EX4200-24PX and EX4200-48PX support PoE+ (IEEE 802.3at - up to 30W per port) and require EX-PWR2-930-AC
- EX-PWR2-930-AC is supported in all EX4200 models
http://www.juniper.net/techpubs/en_US/release-independent/junos/topics/reference/specifications/power-supply-ex4200.html
Some relevant excerpts:
EX4200-24PX and EX4200-48PX switches do not support the 930 W (EX-PWR-930-AC) or the 600 W (EX-PWR-600-AC) AC power supplies that are used in the EX4200-48P and the EX4200-24P switch models. EX4200-24PX and EX4200-48PX switches work only with the power supply labeled EX-PWR2-930-AC. You can find the label on the top of the power supply (see Removing a Power Supply from an EX4200 Switch). The EX-PWR2-930-AC power supply is supported across the EX4200 product line
The PoE power budget for a PoE switch model is determined by the capacity of its power supply. For EX4200 switches, the capacity of the power supply provided with a PoE model is sufficient to supply each PoE-capable port with up to 15.4 W in compliance with the IEEE 802.3af PoE standard.
Starting with Junos OS Release 11.1, EX4200 switches support enhanced PoE, a Juniper Networks extension to the IEEE 302.3af PoE standard. Enhanced PoE permits up to 18.6 W per PoE port. Because the power supply provided with a switch is designed to supply a maximum of 15.4 W per PoE port, if you connect a powered device that draws more than 15.4 W, the PoE power budget might not be sufficient to supply a full 15.4 W to the remaining PoE ports.
EX4200-24PX and EX4200-48PX switches support PoE+, the IEEE 802.3at PoE standard, and permit up to 30 W per port.
jtb