- The Washington Times - Wednesday, March 30, 2005

The first thing Montgomery Village resident Jeanette D’Amour does when she enters a building is look at the ceiling.

An electrical engineer, Ms. D’Amour can identify the type of lighting and the fire-suppression and air-handling equipment from the characteristics of the ceiling devices.

“That tells me what kind of building systems are in the building,” says Ms. D’Amour, electrical department head for E.K. Fox (EKF) & Associates Ltd., a consulting engineering firm in Fairfax City.

Electrical engineers like Ms. D’Amour design the circuitry and equipment that distribute power throughout a building, a task that, like the job of the production crew for a play, is behind the scenes and not something on most people’s minds.

“You’re not supposed to see it if we do our job right,” says Charles Sisung, senior electrical engineer for EKF and president of the Power Engineering Society, the Northern Virginia regional branch of the Institute of Electrical and Electronics Engineers (IEEE). IEEE is a technical professional association based in Piscataway, N.J., that sets international industry standards.

Electrical system design begins at the point where power supplied by an electrical utility company, such as Dominion Virginia Power or Potomac Electric Power Company (Pepco), enters a building. A transformer reduces the voltage carried from an underground cable or overhead lines to a level that is usable for the building.

Service conductors, usually copper wires, carry the power from the transformer to a switchboard or a switch gear, which are built to different standards, located in the main electrical room.

The switchboard or switch gear consists of a large panel with rows of switches and buses that distribute power throughout the building, along with fuses or circuit breakers able to protect the electrical circuit in case of current overload. The fuse link will melt or the circuit breaker will trip, opening the circuit to protect the loads.

A fuse or circuit breaker serves as a current sensor or current-monitoring device, says Charles Kim, assistant professor in the electrical and computer engineering department at Howard University in Northwest.

The current, or flow of electricity through a circuit, is measured in amperes. The amps are multiplied by voltage, or the pressure in the circuit, to determine watts, or power. Utility companies charge by the wattage used each hour, or kilowatt hours.

“Voltage is the power you’re getting. Amps is how much power the equipment draws,” says Russell Simpkins, electrical department head for Strickler Associates Ltd., a consulting engineering firm in Fairfax City.

Electrical equipment that is permanently wired is a fixed load, and plug-in equipment a convenience load, as described in Richard R. Janis and William K.Y. Tao’s textbook “Mechanical and Electrical Systems in Buildings,” Third Edition, published this year.

“Anything that consumes electricity, we call it load,” says Mr. Kim, who holds a doctorate in electrical engineering.

The equipment on each floor of a high-rise building receives power distributed from an electric room on the same floor or from panel boards located within the main electric room. The floor-level electric rooms are connected to the main electric room, typically located in the basement or lower level.

“A lot of times with a high-rise, instead of running wire to each floor, we use busduct, a copper material that can run in one piece from the main service to each floor,” Mr. Simpkins says.

Panel boards or subpanels in each electric room, equipped with switches and circuit-protection devices, distribute power to the separate panels on the floor. Panels with a high voltage, written as 277/480, feed fluorescent lights; motors; and heating, ventilation and air-conditioning (HVAC) systems.

A transformer reduces the voltage to 120/208 volts for the low-voltage panels, which feed receptacles located within outlet boxes and incandescent lighting fixtures.

“Distribution power can be split to general-purpose panel boards, while other uses, such as computers, are segregated into their own panels,” says John “Jack” Thompson, vice president of WFT Engineering Inc., an engineering design firm in Rockville.

The point of power distribution in a single-family home is a 200-amp panel board instead of a switchboard, which can handle 2,000 amps. The standard resident voltage is 110 volts.

“The difference is only in scale and equipment. … There are more loads and larger loads in commercial office buildings than in a house,” says Michael Gentry, senior electrical engineer for WFT Engineering. “Electricity still behaves in the same way.”

Electrical engineers design a building’s electrical system by considering the load, or how much power the building will use, and how the power will be distributed from the switch gear to the panels, says Richard Potts, senior electrical engineer with Clough Harbour & Associates LLP, headquartered in Albany, N.Y. One of its 24 offices is located in Vienna. The load includes lighting, computer equipment and mechanical and electrical equipment, he says.

“Building owners try to save money. One way is to save costs associated with lights,” Mr. Potts says.

Developers use a variety of light fixtures and systems to save costs, such as motion detectors that respond to movement patterns, panels with time clocks set to predetermined times, and photocells that measure the amount of light, all of which control lighting levels.

“Lighting waste is a huge problem. It’s probably one of the biggest energy wastes out there,” Mr. Gentry says. “Light translates to heat. Unnecessary lighting of a building requires the air-conditioning system to run and consume more energy.”

Electrical engineers work within the developer’s budget, taking into account the building’s planned use and the type of equipment it will contain, Mr. Thompson says. To do so, they use computer-aided design tools, such as AutoCAD, along with their experience, knowledge of local amendments and industry codes, and access to vendor catalogs, he says.

AutoCAD allows an electrical engineering staff to use a computer to draw out and place symbols on architectural plans instead of doing the work by hand. The system has the ability to attribute values to the symbols, allowing for faster calculations.

Once the design is completed, the engineering firm contracted to do the work gives the plans to the developer. The developer, in turn, contracts with a general contractor to build out the architectural designs overlaid with the electrical systems. An electrical contractor or electrician installs those systems.

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