Installation and Safety Guide
11
Applying Power to the Switch
Power supply bays are in the rear of the switch. Depending on the model, the
switch may have a PSU, FOM, or blanking plate over a power supply bay.

Connecting an AC power supply

Follow these instructions to connect one of the following to an AC power supply:
■an AT-PWR01, AT-PWR02, or AT-PWR05 AC PSU
■an x900-12XT/S switch
Warni ng The AT-PWR01 AC PSU has a fuse rating of 250 V, 5 A for FH101 and
FH102.
Warni ng The AT-PWR01 AC PSU has double pole/neutral fusing. Electric
shock is possible since there are dual primary fuses, one on the phase circuit and
one on the neutral circuit. If the neutral opens, the phase may still be live.
Warni ng When x900-24 units are connected with VCS stacking cables (XEM-
STK-CBL) ensure that all the PSUs are appropriately grounded. This is to avoid
large circulating ground currents that could damage the stacking cables. To
achieve this ensure that:
■ AT-PWR01 AC is grounded by the 3-pin AC power connector
■ All grounding points are at the same ground level. That is, all power
connectors share a common power distribution unit.
Warni ng For x900-24 models, when using an AT-PWR01 AC power supply and
an AT-PWR01 DC power supply in the same switch, then the ground-terminal of
the DC power connector must be connected to the same ground as the AC
ground pin of the AC power connector.
If this is not possible, then you must ground the AT-PWR01 AC only, and leave
the AT-PWR01 DC power connector ungrounded. In this case, as a safety
precaution, ensure that the rack is also grounded.
Warni ng For SwitchBlade x908 AC models the grounding stud on the rear of
the unit is for supplemental grounding only. The system must be supplied by a
grounded 3 wire AC source through the power supply cord.
Warni ng When SBx908 devices are connected with VCS stacking cables (either
HS-STK-CBL or XEM-STK-CBL), each individual stack member chassis must be
additionally grounded by using the rear grounding-terminal on each device. In
order to avoid large circulating ground currents, the wires of each grounding
cable must be 18AWG or thicker.