Chapter 2
General System and Facility Guidelines
Electrical Factors
30
Electrical Factors
NOTE Electrical practices and suggestions in this guide are based on North American practices. For
countries and areas outside North America, local electrical codes will take precedence over
North American electrical codes.
An example would be the recommendation that the PE (protective earthing) conductor be green
with yellow stripes. This requirement is a North American directive and does not override the
local code requirements for a country or area outside North America.
Local Authority Has Jurisdiction (LAHJ) and should make the final decision regarding
adherence to country-specific or area-specific electrical codes and guidelines.
Throughout this chapter, the LAHJ acronym will be used to indicate Local Authority Has Jurisdiction.
Proper design and installation of a power distribution system for a HP server requires specialized skills.
Those responsible for this task must have a thorough knowledge and understanding of appropriate electrical
codes and the limitations of the power systems for computer and data processing equipment.
In general, a well-designed power distribution system exceeds the requirements of most electrical codes. A
good design, when coupled with proper installation practices, produces the most trouble-free operation.
A detailed discussion of power distribution system design and installation is beyond the scope of this
document. However, electrical factors relating to power distribution system design and installation must be
considered during the site preparation process.
The electrical factors discussed in this section are:
• Electrical load requirements (circuit breaker sizing)
• Power quality
• Distribution hardware
• Grounding Systems
• System installation guidelines
Electrical Load Requirements (Circuit Breaker Sizing) LAHJ
Appendix A summarizes electrical power load (KVA input) requirements for this server but additional
capacity should be added for equipment upgrading or expansion.
It is a good practice to derate power distribution systems for one or more of the following reasons:
• Circuit protection devices should be rated at 20% above the systems root-mean-square (RMS) current
ratings to avoid nuisance tripping from load shifts or power transients.
• Safety agencies derate most power connectors to 80% of their RMS current ratings.
Power Quality
HP equipment is designed to operate over a wide range of voltages and frequencies. However, damage can
occur if these ranges are exceeded. Severe electrical disturbances can exceed the design specifications of the
equipment.
