construction methods to be followed are decided. The engineer determines the loads that the supporting structural members will be required to bear and designs the mechanical systems. such as heating. power. lighting, and plumbing.
As a crew member or a supervisor. you will find the construction drawings. the specifications. and the bill of material your main sources of information during the construction and estimating phases of the project.
Drawings are commonly indexed so you can easily find the sheet you need. The drawing index is located on the cover sheet or sheet 1 of the set. They are divided into eight categories and appear in the following order:
1. Plot and vicinity
2. Landscape and irrigation
8. Fire protection
A working sketch is a drawing made from the working drawings to express a tasking clearly and to provide a quick reference to job requirements. It is drawn to help show actual conditions on the job, what size pipe is to be installed, or where connections will be made. The sketch should show as much detail as possible to help your crew during installation or troubleshooting. A working sketch will usually show the work you want your crew to accomplish in a selected area and will provide ready reference to jobsite conditions.
A crew should have a working sketch with them while working. It will show them how, what, where, and when things happen in the sequence of the job. Your first step in making a working sketch should be to draw the symbols that represent all the fixtures or equipment that is to be installed and locate them within the room. Try to draw them in the sequence of installation and include measurements. The amount of detail you use in a working sketch will be determined by the crew's experience, the complexity of the systems involved, and the need for cooperation with other trades working on the jobsite.
Upon the completion of a facility, the crew leader or project supervisor should provide marked prints that indicate any construction deviations. The information required must show all features of the project as actually, built. As-built drawings should be reviewed after they are completed. This review assures that all information appearing on the drawings shows the exact as-built conditions.
From the as-built drawings, record drawings are prepared. These drawings are the original construction drawings, but they are corrected according to the as- built marked print. They then provide a permanent record of as-built conditions. The final record drawings must be kept up to date at all times. If this maintenance requires a change to the record drawing, then this information should be passed on and the record drawings updated.
To understand the instructions and dimensions on a working drawing, you must be able to read and understand the language of the prints not only for your particular job but also for all the different phases. Plans, specifications, and details go together. It is impossible to use one successfully without the other. Never overlook a reference note on a drawing. The blueprints contain the information and directions that require you to do your part of the total job as planned. It is also important to follow all the instructions on a blueprint faithfully. Any deviation on your part may make it impossible for fellow tradesmen to do their work properly or successfully.
To read blueprints, you must understand the meanings of all devices, such as various lines, symbols, conventions, abbreviations, and methods of giving dimensions and working directions.
The types of lines the electrician should be able to read and understand are given below. In figure 2-1 these lines are shown as they may appear on a drawing.
Trim line: a light, continuous line along which the tracing is trimmed to square the sheet.
Border line: a heavy, continuous line that outlines or borders the drawing. The drawing is complete within this lined border.Continue Reading