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Electrical Engineering in building construction involves the design of the Electrical Power, Lighting, Alarms, Controls and various other electrically related components. Typically the Electrical loads are broken into several components, then added together.

For example: the Electrical Power comprises of general receptacles, A/C units, water heaters, refrigerators, dishwashers, cloths washer, cloths dryers, etc. Each of these items are connected directly to individual circuit breakers at the electric panel. Lighting fixtures are grouped together and are connected to individual lighting circuit breakers.
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Electrical Systems: How to Design Electrical System
Electrical Power = Receptacles, Appliances and Equipment.
Electrical Lighting = Lighting Fixtures.
Alarm Systems = Burglar Alarm Systems.
Controls and other Electrical Components = Garage Door Openers, Gate Controls, etc.
Electrical Power: The Electrical Power Plans contain all components, except lighting, such as, general receptacles, A/C units, water heaters, refrigerators, dishwashers, cloths washer, cloths dryers, etc. Each of these items are connected directly to individual circuit breakers at the electric panel. Also each piece of equipment has name plates which identify the voltage, serial number, model number, the wattage or ampere rating and other information. This information is important when sizing the wires and breakers at the panel.
Elecrtical Lighting: When designing residential Electrical Lighting, the National Electric Code (NEC) permits computing 3 watts per square feet as the wattage design value. This is permitted, eventhough the total wattage may exceed the actual number of fixtures and wattage of the connected fixtures. It is very unlikely that all lights in a building will be turned-on at the same time. However, if lights are intended to be left on all of the time, then these lights need to be added to the design value.
Alarms Systems: There are many type of Burglar Alarm systems available. Among the systems or components available are continuous loop systems, parallel systems, infra-red systems, motion sensors, vibration sensors, etc. These systems may be design as a single system or you may mix these systems and components. For example: you may want a portion of you house protected by a continuous loop system, then you may want several opening (windows or doors) on a parallel system, then you may want a specific room monitored by a motion sensor, and then you may also want a door protected by a vibration sensor. As you can see, you can mix the various type of systems. Usually, a good Alarm System will permit the mixing of various type of protection.

How your building is protected is left up to you.
Controls and other
Electrical Components:
Other Controls that may be used in your residence are the garage opener, gate controls, A/C thermostats, etc. Working or repairing these devices require knowledge of electricity.
General Information:
Putting it together
When you have selected each piece of equipment and lighting to be connected to you panel, you must find the wire size that will be acceptable for that piece of equipment and lighting circuit. Wire sizes for residential electrical use must be a #14 gage wire or greater (smaller numbers indicate a larger wire size). In commercial buildings a #12 gage wire or larger must be used. The Code that is used for all Electrical work is the National Electric Code (NEC). In NEC you find the wire size, which is selected from tables that identify the total amperage that is allowed to flow thru a given wire. The total amperage of all of the wires connected to the panel is used to determine the feeder size, which is the main wires feeding electricity to the panel from the power pole. To compute these actual values there are a series of calculations that are permitted to be used, which take into account demand loads. These demand loads are a reduction in the actual values computed for all of the equipment. By using the allowed demand loads, the wire sizes are less than if we took everything connected at 100%. The Code recognizes, as stated before, that not all equipment and lighting will be turn-on at the same time. The intent here is to enlighten, not to provide a complete solution to a given project. If you desire to see how an electrical schedule is prepared, kindly look at our; How to Design Electrical System.