Powering Up

Many school facilities are ill-equipped to handle the power needed for today's information technology. Often, they do not realize their electrical capacity is insufficient until they have bought hardware and software. Filtered power, sufficient numbers of outlets and adequate grounding are just three examples of common problems encountered in both old and new buildings. Information technology requires a steady electrical current and, depending on the sensitivity of the hardware, must guard against surges and fluctuations.

Planning for informational technology is critical in the design of new or renovated facilities and in the upgrade of existing facilities.

A critical component

Power is the most critical electrical issue affected by informational technology. The obvious starting point is the receptacle where the equipment is connected. Location and quantity must be addressed. The most difficult issue regarding receptacles is obtaining a firm commitment about where the equipment will be situated. Schools want to provide instructional staff with some flexibility regarding furniture arrangement. This flexibility often conflicts with the electrical power system design; most technology devices must be plugged into a hard-wired power source.

Once equipment locations are configured, the number of items to be plugged in must be determined. In the past, a single duplex receptacle was adequate to support a workstation, as only the monitor and CPU required power. Now, however, multiple electrical outlets are the norm, and a quad receptacle at each workstation is common.

The next issue at hand is how many receptacles can be placed on a single circuit. Historically, electrical designs have tried to connect no more than three to four workstations to a circuit. Technology equipment was never to be connected to the same circuit or panel board as other equipment or general-purpose receptacles. Total isolation of technology equipment was believed to be necessary to eliminate noise and harmonics on the circuit. This approach impedes flexibility and raises project costs by increasing the number of electrical circuits and equipment. Now, planners believe that five to six workstations can be connected to the same electrical circuit. The increase has come about in part because of the decreased power consumption of modern equipment.

Another concern with the circuiting of “technology receptacles” is the power requirements of peripheral devices, including printers, plotters, televisions, smart boards and overhead projectors. All of these devices may require a dedicated circuit or two devices per circuit at the most. A separate neutral for each technology equipment circuit is necessary, but there no longer is a need for an isolated ground. The isolated ground was provided to protect against voltage surges, and the use of transit voltage surge suppression (TVSS) at the panel is a more practical and efficient means by which to deal with voltage surges.

TVSS devices should be installed as close as possible to the panel board that serves technology loads. The main service equipment for the building should be outfitted with a TVSS device to protect from surges and spikes generated from the incoming utility. In order to provide a separate neutral, the panel board serving computers and other technology equipment must have a 200 percent neutral. This feature provides for the use of a K-4 rated transformer, which contains double-neutral windings to accommodate the panel board and a separate neutral for each required circuit. This combination ensures the best protection against power surges, and eliminates noise and harmonics on the circuiting.

The most significant benefit to this combination is that other miscellaneous equipment and receptacles now can share the same panel board as computers without fear of noise and surges. This enhances flexibility, as a school can provide technology power almost anywhere within the facility while ensuring that it has clean power.

Some consideration also should be given to serving technology power and large mechanical or kitchen loads from different panel boards. The concern with large mechanical and kitchen loads is because of large voltage drops caused by in rush current (motor startup). Equipment, which has large startup current, can cause a computer to reboot, sensing a momentary “off and on” period.

Typically, schools should take into account not only adequate circuit capacity, but also location and circuit type. The trend in technology focuses on flexibility, which to many means that students and staff should be able to connect to data networks from virtually anywhere in the school. This concept requires a rethinking of the circuit configuration.

Surface-mounted raceway once was considered the primary solution for retrofitting existing facilities with power and low-voltage wiring. The latest trends see this product being used more widely in new facilities as a means of increasing flexibility and facilitating the addition of mounted raceway, cleaning up installations and reducing costs.

Retrofit power

Emergency power in the form of generators or battery backup is an “absolute” in terms of providing an uninterrupted power source for some technology equipment. The cost associated with providing emergency power to student and staff workstations and other general-instruction equipment is cost-prohibitive. Emergency power is imperative for file servers and other critical administrative and instructional hardware. If a generator is provided, it is important to understand that the transfer from normal power to emergency power does not happen instantaneously, as the generator must have time to come up to full speed.

In order to protect equipment and data, an uninterruptible power source (UPS), generally in the form of a battery system, also must be included to provide a seamless transition from normal power to emergency generator power. UPS is rated only for 90 minutes of power and should not be considered a single source of emergency power. These UPS fixtures also give instructional areas a high-tech, modern look. Be wary of using discounted surge protectors to meet the above requirements. They typically provide little real protection in the event of a serious power-line disturbance.

Light it up

Lighting and lighting control are critical aspects of technology support. Objectives focus on providing not only adequate light and the proper type of lighting, but also lighting control that facilitates a variety of data and video activities. Popular lighting choices for technology environments are indirect lighting fixtures or parabolic diffuser fixtures. These forms of light significantly reduce glare, the No. 1 problem for monitors and video screens. Indirect lighting provides ambient lighting that uses soft, diffused lighting to minimize glare and video projection washout. Parabolics provide cutoff capabilities with a direct component and no spill to create glare on monitors. If possible, fixtures should be spaced to avoid being directly over workstation locations. These lighting types generally add cost to the project, as more fixtures are required to meet general illumination needs, manufacturing cost, and quality of material for specialty fixtures.

Lighting control has become more important than source types in many cases. Being able to reduce space-lighting levels uniformly by 50 percent is considered an absolute minimum. Providing either 100 percent, 66 percent or 33 percent lighting is more the norm in current instructional space design. Beyond these basic considerations, darkening 50 percent or 66 percent of the entire room is becoming a more common design consideration. Switching becomes critical for computer labs where projection devices are used as a visual aid. Ideally, all lighting affecting the projection surface area would be turned off. However, during the projection display, students are taking notes and total darkness is unacceptable. To alleviate this scenario, it has become common practice to have separate switching for the two rows of lights closest to the projection screen.

Two other methods for providing a low level of lighting during a projection presentation would be providing a second source of incandescent dimming fixtures, or direct task lighting in the form of under-cabinet fixtures.

Capps is principal, construction administration, and Jones is an associate and electrical engineer for Hickman-Ambrose Inc., Consulting Engineers, Chesapeake, Va. Day is senior analyst with KBD Planning Group, Inc., Bloomington, Ind., and AS&U's “Tech Talk” columnist.


NOTABLE

  • 90

    Minutes of power rated for an uninterruptible power source (UPS).

  • 50

    Minimum percentage by which a school should be able to reduce space-lighting levels.

  • 50, 66

    Percentage of room lighting to be darkened; this is becoming a more common design consideration.

  • 100, 66, 33

    Percentages by which most schools should be able to reduce their lighting levels.


SIDEBAR: Key electrical questions

  • Can the existing electrical capacity support the technology?

  • Is the power supply uninterruptible?

  • Are there sufficient numbers of electrical outlets in the room?

  • Is there room for expansion to handle future technology applications?

  • Are there existing devices, systems or motors within the building that could cause network interference?

  • Is the technology equipment guarded against surges? If so, can the power suppressor provide real protection in the event of a serious power-line disturbance?

  • Have you communicated with the electrical engineer or planner to ensure that electrical specifications are aligned with educational technology needs and applications?

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