ELECTRICAL ENGINEERING DESIGN PROCESS

Depending on the client, specific codes need to be followed while others are used for recommendations. Example of electrical engineering codes, guidelines, standards, and recommendations are as follows: National Fire Protection Association (NFPA, a.k.a. National Electrical Code) 70 is the electrical code, NFPA 99 is the Health Care Facilities Code which has specific electrical code requirements for health care facilities, and NFPA 77 is the Recommended Practice on Static Electricity. An understanding of what is mandatory, standard, or recommendation needs careful attention during the electrical system design process. The electrical system consists of power distribution, emergency, lighting, grounding, and other disciplines. Other disciplines include telecommunication, fire alarm, and mechanical coordination, to name a few. Regarding power distribution, the first consideration is to estimate the building load. What is the total power consumption (KVA) or current (Amps) of the building? Coordination with the service entrance or utility company will be required to confirm what voltage is available, the size of the service transformer, and the short circuit contribution to the system. Once the estimated load is determined and coordination with the utility company is completed, sizing major electrical distribution equipment can begin. Major electrical distribution equipment includes switch-gears, switchboards, transformers, motor control centers, and panel boards. The emergency system for the building is analyzed and determined based on its occupancy as determined by NFPA and specific client-mandated codes, such as the Unified Facilities Code (UFC) for military installations. Major equipment for the emergency system includes generators, ATS, UPS, parallel switch-gears, etc. Studies are conducted using manual or software techniques to determine and confirm the sizes of the power distribution and emergency equipment. Another important system is lighting. The lighting design process begins with identifying the intended use of each areas or room. The Illuminating Engineering Society of North America provides standards for minimum lighting requirements, measured in foot-candles. Grounding, which is the most important system of all from a safety standpoint, provides protection against electrical shocks and hazards to occupants. The grounding conductor is installed in direct contact with the metal enclosure that will provide a direct path back to earth, rather than through the next person touching the metal enclosure. The importance of grounding is highlighted if the insulation on the wires has deteriorated or burned due to overload, and is now exposed and in contact with the metal enclosure. This general overview of the electrical design process gives an understanding of the importance of the statement of work, the electrical codes and standards, and the electrical systems involved.