Appendix C. Safety and Protection Equipment
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Appendix C. Safety and Protection Equipment

Depending on the location and size of an installation site, consider the following for safety and protection:

Installing Cable-Management Equipment

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

Install cable-management equipment if:

  • People require access to locations with power cables or connections

  • Power cables could become disconnected

  • Power cables pass across aisles or other paths.

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

Warning: Check the cable-management equipment specifications for power cable limitations. Improperly installed cable-management equipment can cause unsafe working conditions.

Emergency Power-Off Switch

An emergency power-off (EPO) switch is a safety feature that protects people and equipment from these hazardous electrical situations:

  • Personnel are exposed to or in contact with electrical sources

  • Large installations have many components to power off quickly during emergencies

  • Site is subject to power outages, drop-outs, and surges.

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

Warning: A licensed electrician should perform all wiring to ensure that the installation meets local and country electrical codes.

Fire-Fighting Equipment With an Electrical Rating

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.

Note: While Halon fire-protection systems are ideal for suppressing fire without damaging computer equipment, Halon systems are being phased out because of their deleterious effects on the environment. If a site already uses Halon, check the national and local environmental codes and guidelines and plan accordingly.

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

Warning: Use licensed professionals to install extensive fire-protection systems. Room-level fire protection typically relies on gas evacuation within an enclosed area. In addition, adequate warnings, overrides, and training must be provided to ensure people's safety.

Lightning Protection

Install lightning protection at the site if:

  • the site is in an electrical storm area

  • the local utility company uses lightning protection on the primary power source

  • overhead power lines provide the site's primary power.

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 at the installation site.

Power-Line Treatment

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 power-line quality, including:

  • line conditioners

  • line regulators

  • isolation transformers

  • uninterruptible power supplies ( UPS) and standby power supplies ( SPS).

    Caution: When selecting a UPS or SPS, it is important to consider the inrush current of the systems to be powered. Failure to do so could result in equipment damage or even personal injury. See “ Electrical Requirements” in Chapter 2 and the power sections in chapters 3 through 8 for help in selecting a UPS or SPS.

The size of a UPS or SPS should take into account both the wattage and the VA rating of the systems it will power. Since many SGI systems are power-factor corrected, the watt and VA ratings may be very similar. However, not all systems are power-factor corrected. Additionally, basing the size of a UPS or SPS on the VA rating alone is not sufficient. In some cases a UPS may be rated to handle the VA loading of a particular system, but will not be able to handle the watt loading of the same system.

SGI strongly recommends that UPS or SPS power sources used with SGI systems produce a sine wave output. In no event should SGI systems be used with power sources producing a square wave output.

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

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Appendix B. Site Power and Power Cables  Index