The Meaning of Symbols 203
When a large area is made up of one material, it is common to only draw the symbol in a part of the
area. Some drafters simplify this even further by using a note to indicate what material is used and omit-
ting the symbol altogether (Figure 8.6).
Throughout the remainder of this text, material symbols are presented as they appear in plan and
elevation views. Many symbols are designed to approximate the actual appearance of material. This is
especially true on elevation drawings, as shown in Figure 8.6. Because of the complexity and space re-
quired, many symbols do not have any graphic relationship to the items they represent. These must be
memorized if drawings are to be consistently interpreted. When material symbols are similar, always
look for a notation, different view, detail, or specification for information about the material.
8.4 ELECTRICAL SYMBOLS.
Electrical drawings—like other types of building-construction drawings—must be prepared by compe-
tent electrical drafters in a given time period to avoid unnecessary delays. Symbols are used on electri-
cal drawings to simplify the drafting work for both the drafters and the workers interpreting the drawings.
It should be noted that electrical symbols are not standardized throughout the industry, which is one rea-
son why electrical drawings typically have a symbol legend or list.
Many electrical symbols are used to show the desired lighting arrangement. Switch symbols are
usually placed perpendicular to the wall and read from the right side or bottom of the sheet. Figure 8.7
shows two lists of electrical symbols currently in use on most electrical drawings. The lists represent a
good set of electrical symbols in that they are easy to draw, easily interpreted by workers, and sufficient
for most applications.
The electrical system for a small property would typically include wiring as well as devices such as
switches, receptacles, light fixtures, and appliances. Wiring is indicated by lines that show how devices
are connected. These lines are not shown in their actual position. They simply indicate which switches
control which lights. Outlets (receptacles) and switches are usually shown in their approximate positions.
Major fixtures and appliances are shown in their actual positions. In Figures 8.8, 8.9, and 8.10 we see
examples of receptacle symbols, alarm symbols, and other electric symbols.
Some of the symbols listed contain abbreviations, such as TV for television outlet and WP for weath-
erproof. Others are simplified pictographs, such as the symbol for an electric meter. One way to develop
the ability to interpret a drawing and its symbols is by first learning the basic form of the different sym-
bols. This is because many symbols are similar (square, circle, etc.), and the addition of a line, letter, or
number determines the specific meaning of that symbol.
8.5 PLUMBING SYMBOLS.
One must differentiate between industrial and residential or commercial piping. Industrial piping is gen-
erally designed to carry liquids and gases used in manufacturing processes. In heavy construction steel
pipes have welded or threaded fittings and connections. Piping used in commercial and residential ap-
plications is generally termed “plumbing” and is designed to carry fresh water, liquid and solid wastes,
and gas. These pipes can be made of plastic, copper, galvanized steel, or cast iron. In preparing a
plumbing drawing, all pipe fittings, fixtures, valves, and other components are represented by symbols