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Level 04a, June 21, 2004
Grounding Specifications
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Table 3-3. Power Plugs and Receptacles - 200-240 Volts (continued)
Feature Code
Voltage
Notes:
1. IBM continues to strongly recommend the use of a metal backbox (example shown
below) with our line cords using IEC-309 plugs. Although in-line connectors and
nonmetalic backboxes are available and compatible, they are not recommended. These
recommendations are based on the metal backbox providing:
v An added level of protection against a miswired phase and ground reversal
v In some cases, a metal backbox may be better for EMI mitigation
You may choose not to use a metal backbox. In this case, please check your local code
for specific requirements.
2. The customer must obtain appropriate plugs and receptacles, based on existing
electrical codes, where those plugs and receptacles are not provided with the system.
Every single-phase branch circuit must contain two phase conductors (or one phase
and neutral) and an insulated equipment-grounding conductor.
For 200 V ac through 240 V ac installations in the United States, the
equipment-grounding conductor must be identical in size, insulation material, and
gauge to the branch circuit phase conductors, except that it must be green with or
without one or more yellow stripes on the insulation. For installations outside the
United States, the size of the grounding conductor must be in accordance with local
codes.
Conduit must not be used as the only grounding means. However, any conduit or
cable shield must be connected at both ends in such a way that it is included in the
grounding path in parallel with the grounding conductor it contains. IBM strongly
recommends that branch circuit wiring be located in metallic conduit, or be made
from shielded cable, if located under a raised floor. Even when not required by local
regulations, some form of shield around the branch circuit wiring is preferred as a
means of reducing coupling of high-frequency electrical noise into signal and control
cables.
There is information about additional recommendations and requirements for
equipment grounding on IBM's Resource Link web site
(http://www.ibm.com/servers/resourcelink). See "General Information for Planning a
Physical Site".
Description
Watertight Plug
Chapter 3. Power Requirements
Watertight
Receptacle
3-3
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