Electrical symbols appear in schematics for devices and locations that include electrical wiring and components. These symbols are often found in electrical schematics for house and business designs as well as in electrical schematics for devices such as computers and televisions. The symbols help to explain the abstract nature of electrical schematics and help designers plan current and future designs.
Current Distribution Symbols
Current distribution uses the "~" symbol to signify the relationship between alternating current m-phases and frequency. The term "1~50 Hz," for example, signifies a single-phase alternating current with a frequency of 50 hertz. The term "3~50 Hz" states a three-phrase alternating current with a frequency of 50 hertz.
A long, straight line signifies direct current. For example, the term "110 V ---- 110 V" states a direct current relationship between two 110-volt sources.
A "+" symbol shows positive polarity while "-" shows negative polarity.
Common Outlet Symbols
Outlet symbols are defined using a circle. If the circle has a line extending from it, the outlet is placed on a wall. If no line exists, the outlet is intended for a ceiling. Any letters in the circle determine the type of outlet. If no letters are used, then it is a general outlet.
Common letters include "F" for fan outlets, "J" for junction boxes, "L" for lamp holder, "S" for pull switch, "X" for exit light and "B" for blanked outlet.
A circle with no outer line and a center black dot signifies a floor outlet.
Powered wires are displayed with straight single lines on electrical schematics. Different types of lines show different types or locations of these wires. A staggered line shows an underground line, while a line with alternating short and long dashes shows wires concealed in floors. Solid lines mean existing wires, and lines with a long dash and three short dashes mean planned wiring. A circle intersecting a solid line designates an overhead line.
Line intersections can be shown using three common symbols. Two lines intersecting as well as one line "crossing" another using an inverted "U" mean that the lines are not connected. Two lines intersecting with a solid dot on the intersection point means that the two lines are connected.
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