IBM System x3750 M4 Installation And Service Manual page 125

Statement 31:
DANGER
Electrical current from power, telephone, and communication cables
is hazardous.
To avoid a shock hazard:
Do not connect or disconnect any cables or perform installation,
maintenance, or reconfiguration of this product during an electrical storm.
Connect all power cords to a properly wired and grounded power source.
Connect to properly wired power sources any equipment that will be attached to this product.
When possible, use one hand only to connect or disconnect signal cables.
Never turn on any equipment when there is evidence of fire, water, or structural damage.
Disconnect the attached ac power cords, dc power sources, network connections,
telecommunications systems, and serial cables before you open the device covers,
unless you are instructed otherwise in the installation and configuration procedures.
Connect and disconnect cables as described in the following table when
you install, move, or open covers on this product or attached devices.
To Connect:
1. Turn OFF all power sources and equipment that is to
be attached to this product.
2. Attach signal cables to the product.
3. Attach power cords to the product.
For ac systems, use appliance inlets.
For dc systems, ensure correct polarity of -48 V dc
connections: RTN is + and -48 V dc is -. Earth
ground should use a two-hole lug for safety.
4. Attach signal cables to other devices.
5. Connect power cords to their sources.
6. Turn ON all the power sources.
Statement 34:
CAUTION:
To reduce the risk of electric shock or energy hazards:
• This equipment must be installed by trained service personnel in a
restricted-access location, as defined by the NEC and IEC 60950-1,
First Edition, The Standard for Safety of Information
Technology Equipment.
• Connect the equipment to a properly grounded safety extra low
voltage (SELV) source. A SELV source is a secondary circuit that
is designed so that normal and single fault conditions do not
cause the voltages to exceed a safe level (60 V direct current).
• Incorporate a readily available approved and rated disconnect
device in the field wiring.
• See the specifications in the product documentation for the
required circuit-breaker rating for branch circuit
overcurrent protection.
• Use copper wire conductors only. See the specifications in the
product documentation for the required wire size.
• See the specifications in the product documentation for the
required torque values for the wiring-terminal screws.
To install a 750-watt -48 V to -60 V dc power supply, complete the following steps:
To Disconnect:
1. Turn OFF all power sources and equipment that is to
be attached to this product.
For ac systems, remove all power cords from the
chassis power receptacles for interrupt power at the
ac power distribution unit.
For dc systems, disconnect dc power sources at the
breaker panel or by turning off the power source.
Then, remove the dc cables.
2. Remove the signal cables from the connectors.
3. Remove all cables from the devices.
Chapter 2. Installing optional devices
107