46 Modern Commercial Wiring Copyright Goodheart-Willcox Co., Inc. the mark in the lighting fi xture schedule. The schedule provides the exact type of fi xture and lamps. Receptacle Symbols Symbols on the electrical plan identify the locations and types of receptacles. Special or unusual receptacles are clearly marked. Cir- cuit lines may be used to show the connections between receptacles. See Figure 4-5. Additional Symbols Other standard electrical symbols are shown in Figure 4-6. These symbols can be used in any type of electrical drawing. Becoming familiar with these common symbols will improve your print reading skills. 4.1.3 Categories of Electrical Drawings There are several types of electrical diagrams and drawings. The type of drawing used is determined by what the drawing intends to show. The following are some of the most com- mon types of electrical drawings: • Electrical plans • Schematic diagrams (elementary diagrams) • Single-line drawings (one-line diagrams) • Schedules. Electrical Plans Electrical plans show the basic fl oor plan (walls, doors, windows, and stairs) along with the installed electrical devices. For small projects, a single electrical plan may be suffi cient to show all the electrical equipment and connections. However, for most commercial projects, two electrical plans are used. See Figure 4-7. An electrical lighting plan shows switches, lighting outlets and fi xtures, and the conduc- tors connecting them. An electrical power plan shows receptacle outlets and equipment with electrical feeds. Panels are often shown on both types of plans. Electrical plans include marks that reference schedules, elevations, sections, and detail draw- ings. Other types of electrical diagrams are included to help clarify circuits and connections. DW R C F Special- purpose connection (dishwasher) Single receptacle Quadruplex receptacle Single special- purpose outlet Duplex special- purpose outlet Duplex receptacle Triplex receptacle Range outlet Clock hanger receptacle Fan hanger receptacle Floor single receptacle Floor duplex receptacle Floor special- purpose outlet Floor telephone outlet (public) Floor telephone outlet (private) Ganged floor outlet Underfloor duct and junction box Split-wired duplex receptacle Split-wired triplex receptacle Goodheart-Willcox Publisher Figure 4-5. Standard receptacle symbols. Flush-mounted panelboard Switchboard External disconnect Surface-mounted panelboard Motor controller Controller and disconnect Trolley duct Cable tray Wireway Busway B B B T T T BP BP BP W W W MC Goodheart-Willcox Publisher Figure 4-6. Miscellaneous electrical symbols.