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
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
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 crews 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.
TYPES AND WEIGHTS OF LINES
FOUND ON DRAWINGS
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.