A takeoff is counting what the job needs off the drawing -- and what it needs is always more items than there are symbols.
Under-order and the job stops. Over-order and the money is gone. Both happen for the same reason: counting the symbols and forgetting everything each symbol implies.
Take ten device locations. That is not ten parts. Each one needs a box. Each box needs a fitting, sometimes two. Then the device, then the plate, then the connectors and the fasteners. Ten symbols on a drawing can be sixty or seventy items on an order, and the ones left off are never the devices -- they are the small parts nobody thinks to count.
Check yourself: A drawing shows ten device locations. Do you order ten parts?
Answer: No. Ten device locations can require more than ten individual parts.
A symbol on a drawing marks a location, not a component. Everything that location needs -- box, fitting, device, plate, small parts -- has to be counted for each one.
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Written from the owner's poster for this lesson. Nothing added beyond what the poster states.
Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.
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