Electrical Circuit and Wiring Information B-1Appendix BElectrical Circuit and Wiring InformationB-For electrical circuit and wiring information that you need to provide to the contractorand/or facilities personnel responsible for wiring the power at the system installationsite, see:• “Fault Protection Requirements” on page B-1• “Grounding Considerations” on page B-1• “Circuit Wiring Diagrams” on page B-3• “Electrical Power Connectors” on page B-9Fault Protection RequirementsEach enclosure in Express5800/320Ma 3.2 GHz, 3.6 GHz, or Dual-Core systemscontains internal fault/overload current protection. However, the system relies on thepower distribution system at your site for protection against potential faults in the powercords and the wiring in the system base.• If you are using a pair of PDUs in the cabinet, use 30A or less circuit breakers ineach power distribution branch that feeds the PDUs.• To connect a single system to power, use 20A or less circuit breakers in each powerdistribution branch that feeds the systems.Grounding ConsiderationsThe system obtains an earth reference ground through the power cords attached to thesystem. Similarly, each peripheral device connected to the system obtains groundthrough its power cord. For each peripheral device, you must ensure that ahigh-integrity safety-ground conductor is installed as part of the wiring system (inaccordance with U.S. national electric code NFPA 70 or the equivalent). Theinternational safety standard (EN60950) for electronic data processing (EDP)equipment also requires a ground conductor, but calls it a protective earth (PE) ground.Depending upon local conditions, ground potentials may differ between the systembase and any peripheral devices connected to the system base. All grounds in thesystem must return to the same reference point in the power distribution system, asclose as possible to zero (0) volt potential relative to earth reference ground. Earth
