Refer to chapter 8 of this book to review the basic functions of the components associated with the mechanical systems and the methods used in the development of a mechanical plan. This section will focus on the procedures applicable in drawing plumbing plans for residential and commercial buildings.

In some residences and commercial structures, a separate mechanical plan is drawn to show fixtures, water supply and waste disposal lines, equipment, and other supply and disposal sources. In drawing a plumbing plan, the following procedures apply:

1. Trace the floor plan, showing all exterior and interior walls, major appliances, and plumbing fixtures. Orient your drawing so that enough space is left for fixture schedules, legends, details, or other related information. Note that the outline of the building is drawn in thin but visible lines.

2. Draw the water-supply line from the source into the house, and then, one by one, to all of the fixtures. Use the appropriate line thickness and symbols for drawing valves, fittings, and pipe sizes. Next, draw the disposal system. Start the layout with the house or building drain from just outside the building. Also, locate the waste and vent stack at this time.

3. Add a symbol legend, drawing title, notes, and scales, and fill in the title block. Go over and double-check the dimensions and the checklist. As you can readily tell from figure 8-27 in chapter 8, plumbing plans alone can become extremely difficult to read and fully comprehend. For this reason, it is general practice to prepare and include riser diagrams, such as those shown in chapter 8, figures 8-24 through 8-26. These isometric drawings are much easier to understand and are invaluable to those responsible for preparing material estimates and to the craftsmen (UTs) responsible for installing plumbing systems. As alluded to in chapter 8, the mechanical division of a set of construction drawings will include, in addition to plumbing plans and details, drawings for any heating, ventilation, and air-conditioning systems that a building might contain. Frequently, the drawing sheets in the mechanical division are identified by the designating letter M in the title block. However, remember that in the order of drawings, these sheets containing heating, ventilation, and airconditioning drawings will precede those for plumbing.

The electrical systems and plans, as described in chapter 9, consist of the basic functions of the components associated with electrical distribution and interior wiring and the methods used in the development of an electrical plan. This section, however, emphasizes the procedures used in preparing an electrical drawing or plan. It is important for an EA not only to understand the symbols and drafting methods used here, but also to learn a great deal about how the system works, the safety of the system, and the minimum requirements of local and national codes included in the drawing. The drawing sheets in the electrical division of construction drawings are frequently identified by the letter E in their title blocks.

In drawing the electrical plan, follow the same approach used in the mechanical drawing, such as using the correct line thickness and proper orientation. To the fullest extent possible, be sure, also, to use the standard electrical symbols discussed previously in the text.

1. After the floor plan is traced, locate the meter and service panel, noting the voltage rating and the amperage. Locate all of the convenience outlets, ceiling and wall fixtures, and other electrical devices required with the appropriate symbols.

2. Locate all of the switches; connect the switches to the fixtures or convenience outlets, using a template or a french curve. The curved lines may be solid or dashed, and should be included in the symbols list. Add the circuits, the circuit numbers, and the circuit notations.

3. Next, add a symbol legend and a fixture legend (if required). Place the drawing title, note the scale, and fill in the title block. Again, go over your drawing for completeness and accuracy.