On a structural drawing, what does the symbol '#4 @ 12" O.C.' typically indicate?
Correct Answer
D) Number 4 rebar spaced 12 inches on center
The '#4 @ 12" O.C.' notation indicates Number 4 reinforcing bar (rebar) placed at 12-inch intervals on center. This is standard structural drawing notation for reinforcement placement.
Why This Is the Correct Answer
The '#4 @ 12" O.C.' notation is standard structural drawing symbology where the '#' symbol always indicates rebar size designation, '4' refers to Number 4 rebar (which has a 1/2-inch diameter), '@' means 'at' or spacing interval, and 'O.C.' stands for 'on center' meaning the measurement is from center-to-center of each bar. This is universally recognized notation in construction drawings for reinforcement steel placement specifications.
Why the Other Options Are Wrong
Option A: 4-gauge wire at 12-volt capacity
Anchor bolt specifications are typically shown with different symbols and would include threading information, length specifications, and embedment details. The '#' symbol is exclusively used for rebar designation, not for counting anchor bolts per linear measurement.
Option C: 4-inch diameter pipe at 12-inch intervals
This notation has nothing to do with electrical systems. Wire gauge uses 'AWG' designation, voltage specifications use 'V', and electrical symbols are completely different from structural reinforcement notation. The 'O.C.' terminology is not used in electrical specifications.
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