• Any product or component that plugs into either an IBM power distribution unit or mains power (by
using a power cord), or uses any voltage over 42 V ac or 60 V dc (considered to be hazardous voltage)
must be Safety Certied by a Nationally Recognized Test Laboratory (NRTL) for the country in which it is
installed.
Some of the items that require safety certication might include the rack or cabinet (if it contains
electrical components integral to the rack or cabinet), fan trays, power distribution unit, uninterruptible
power supplies, multi-outlet strips, or any other products that are installed in the rack or cabinet that
connect to hazardous voltage.
Examples of OSHA-approved NRTLs for the US:
– UL
– ETL
– CSA (with CSA NRTL or CSA US mark)
Examples of approved NRTLs for Canada:
– UL (Ulc mark)
– ETL (ETLc mark)
– CSA
The European Union requires a CE mark and a Manufacturer's Declaration of Conformity (DOC).
Certied products must have the NRTL logos or marks somewhere on the product or product label.
However, proof of certication must be made available to IBM upon request. Proof consists of such
items as copies of the NRTL license or certicate, a CB Certicate, a Letter of Authorization to apply the
NRTL mark, the rst few pages of the NRTL certication report, Listing in an NRTL publication, or a copy
of the UL Yellow Card. Proof should contain the manufacturers name, product type, and model,
standard to which it was certied, the NRTL name or logo, the NRTL le number or license number, and
a list of any Conditions of Acceptance or Deviations. A Manufacturer's Declaration is not proof of
certication by an NRTL.
• The rack or cabinet must meet all electrical and mechanical safety legal requirements for the country in
which it is installed. The rack or cabinet must be free of exposed hazards (such as voltages over 60 V dc
or 42 V ac, energy over 240 VA, sharp edges, mechanical pinch points, or hot surfaces).
• There must be an accessible and unambiguous disconnect device for each product in the rack, including
any power distribution unit.
A disconnect device might consist of either the plug on the power cord (if the power cord is no longer
than 1.8 m (6 ft)), the appliance inlet receptacle (if the power cord is of a detachable type), or a power
on/off switch, or an Emergency Power Off switch on the rack, provided all power is removed from the
rack or product by the disconnect device.
If the rack or cabinet has electrical components (such as fan trays or lights), the rack must have an
accessible and unambiguous disconnect device.
• The rack or cabinet, power distribution unit and multi-outlet strips, and products that are installed in
the rack or cabinet must all be properly grounded to the customer facility ground.
There must be no more than 0.1 Ohms between the ground pin of the power distribution unit or rack
plug and any touchable metal or conductive surface on the rack and on the products that are installed in
the rack. Grounding method must comply with applicable country's electric code (such as NEC or CEC).
Ground continuity can be veried by your IBM service personnel, after the installation is completed, and
must be veried before the rst service activity.
• The voltage rating of the power distribution unit and multi-outlet strips must be compatible with the
products plugged into them.
The power distribution unit or multi-outlet strips current and power ratings are rated at 80% of the
building supply circuit (as required by the National Electrical Code and the Canadian Electrical Code).
The total load that is connected to the power distribution unit must be less than the rating of the power
distribution unit. For example, a power distribution unit with a 30 A connection is rated for a total load
76
Power Systems: Site and hardware planning
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