Use Table 4-1 to determine the power requirements for each type of chassis. If you have multiple systems, each chassis must be separately plugged into its own circuit with circuit breaker protection.

A deskside server system always uses 110VAC wiring (except in Japan, where it is 95VAC). For a deskside graphics chassis, determine the number of devices in the existing configuration and add any planned future devices. If the total exceeds the number of devices shown in Table 4-2, install 220VAC wiring. It is much easier to install ample power during initial preparation than to upgrade power later when wiring is already in place and a site is in operation. If a chassis is unlikely to exceed the quantities shown in Table 4-2, install 110VAC wiring.

For a rackmount chassis, determine if the chassis will have a third cardcage added when this option is available. For chassis requiring the third cardcage, prepare the circuit so that it is easily changed to 3-phase when required. Preparing the circuit in advance is much easier than upgrading power later when wiring is already in place and the site is in operation. If there are no plans to include a third cardcage in the chassis, wire the circuit for 220VAC 1-phase power.

Table 4-3 provides KVA (kilo voltamps) and KBTU (kilo British thermal units) ratings for the Challenge/Onyx deskside and rackmount systems. These values help to determine the type of uninterruptible power supply (UPS) to purchase for these systems.

For installations with more than two or three chassis, create a power budget and wiring scheme that considers both existing equipment and future expansion. Considerations include:

Ensure that power outlets are within the maximum cabling distance of the chassis and monitors. Monitors require a wall outlet since the chassis do not provide any peripheral power outlets. The typical cable length is 10 feet. See Table 4-6 and Table 4-7 through Table 4-15 for more details on cables.

Maximum cable lengths are based on the wire gauge of the standard power cables. Consult with a licensed electrician to determine the wire gauge for custom cables.

Make sure that power cables are properly routed and guarded, particularly in areas frequented by personnel. Check the cabling plans to verify that sufficient length is allowed for proper slack through all routing, especially for indirect routing that runs cables along walls or in ceiling racks.

If an existing main power circuit is selected for the new computer equipment, check the circuit for any electrical noise-generating equipment, such as motors, calculators, and typewriters, and transfer these devices to a circuit other than ones servicing computer equipment.

Evaluate the quality of the power supplied by the local power company. Reliable computer operation requires power that is mostly free of fluctuations, transients, surges and spikes, and noise. If the local power quality is questionable, line conditioning equipment may be required.

Install a main branch circuit panel with properly rated circuit breakers for each branch circuit in the panel. Consider adding an emergency power shutdown control to this main panel, as discussed in Section 4.3.2, "Emergency Power Shutdown Control."Figure 4-1 shows the wiring for a main branch circuit panel.

Provide a separate power circuit for each chassis. Wire the circuits using the diagrams and tables in this section for the deskside and rackmount chassis.

Table 4-6 summarizes the power cables and connectors for each power configuration, and Table 4-7 through Table 4-15 shows the physical appearance of each standard cable.

This section provides wiring diagrams for Challenge/Onyx internal power circuits.

Cable management equipment protects personnel from electrical accidents and equipment from premature wear and accidental loss of power. Cable management equipment includes cable routing guides and trays, walkway guards, and plug restraints.

Install cable management equipment if:

Always isolate power cables from signal cables to minimize the transmission of noise from the power to the signal cables.

An emergency power shutdown control is a safety feature that protects personnel and equipment from these hazardous electrical situations:

Install an emergency power shutdown control at the main entries to the computer location. For large installations, place an additional control within easy reach of the main administrator's station. The control must be wired to the main branch circuit panel to disconnect power to all computer equipment at the location.

Check the site for adequate fire fighting equipment for the new computer devices. Place an adequate number of small fire extinguishers (rated for electrical fires) at entrances, exits, and other obvious locations. Bear in mind that some fire extinguishing equipment leaves no residue, while other equipment can destroy sensitive components and surfaces.

For larger installations involving several system chassis, consider isolating all computers in one room and providing room-level fire protection.

Install lightning protection at the site if:

Lightning protection also helps prevent damage at locations with large power surges, such as in some industrial settings and at locations with older or overburdened power grids.

Consult with a licensed professional or appropriate organization for assistance with lightning protection systems within the site's area.

For more information on protecting people and equipment from lightning hazards within the U.S., obtain a copy of The National Fire Protection Association's Lightning Protection Code (NFPA Standard 78).

Power-line treatment may be required if the site uses unreliable power, with problems such as fluctuating voltage, transients, surges and spikes, and noise. Common causes of unreliable power are old wiring, load-switching equipment, such as welding and plating devices, and variable-speed motors or motors that start and stop frequently.

A variety of devices are available to improve the quality of a power line, including:

Consult with a licensed professional or an appropriate organization for assistance with selecting and installing power-line treatment equipment.

For more information on power treatment within the U.S., contact these organizations: