Drafting Light Plots Drawing Booms

How to Draft a Boom on a Light Plot: Symbols, Techniques, and Best Practices

Drawing booms is an essential skill for stage lighting professionals—especially those working in theatre, events, or dance. Booms (vertical lighting positions built from upright pipes) allow you to position lights at varying heights for side or special illumination. Hand drafting these booms on a light plot using USITT-recommended symbols ensures clarity and industry-standard communication. Here’s a step-by-step guide to drawing booms by hand, with expanded technical details and practical drafting tips.

What is a Boom?

A boom is a vertical pipe (often set on a weighted base) used to support lighting fixtures at various heights off the floor. In stage plots, you’ll see booms represented as circles and lines—with “side arms” (horizontal extensions) to hold fixtures in position. Booms are foundational for side lighting in theatre and dance, and understanding their notation is important for both electricians and designers.

Standard Boom Components and Symbology

• Boom base: Drawn as a heavy dot or circle at the floor level, it anchors the pipe.

• Vertical pipe: Represented by a double line or single vertical line through the center of the base.

• Side arms (also called “T’s”): Short horizontal lines extending from the vertical pipe; these hold lighting units away from the boom.

  • Single side arm: One horizontal extension.

  • Double T side arm: Two extensions, often for multiple fixtures at a single height.

• Break lines: If your boom is tall (e.g., 12ft or more), a jagged “break” in the line is used to condense the drawing; indicate overall height with a clear dimension.

*Tip: Always include clear vertical measurements for side arm heights (e.g., +2ft, +4ft etc..

How to Draw a Boom by Hand: Step-by-Step

1. Draw the Boom Base and Vertical Pipe

• Place your center circle at the appropriate stage location on your plot.

• Draw a heavy dot or circle for the boom’s base (shows where the boom is placed).

• Draw the vertical line (boom pipe) upward from the center—use a straight edge or ruler for a clean line.

2. Add Side Arms and Fixtures

• Draw horizontal side arms (using a triangle or T-square for accuracy) at designated heights from the floor.

  • Clearly label each arm’s height (e.g.,+2′-0″, +4′-0″, etc.).

  • Side arms can be singles or doubles, depending on how many fixtures you plan to hang at each level.

• Place your lighting units on each arm:

  • Use USITT-approved symbols for each fixture type.

  • On sidearms, fixtures are drawn close together—it’s common to use a 9-inch centers guideline (vs. 18-inch for overhead pipes).

  • Mind the spacing to allow for fixture adjustment and shuttering—real-world usability matters!

3. Break Lines for Tall Booms

• If your boom is too tall to fit on the plot at scale, insert a jagged break line in place of the missing pipe length. This indicates to readers that vertical space is intentionally compressed for clarity.

• Always label the total boom height clearly next to the break.

4. Crosshatching and Detailing

• Use a 45-degree triangle and a very sharp pencil to add crosshatches on the pipe symbol, denoting the ‘metal’ or structural nature of the boom.

• Crosshatch lines should be thin and at a consistent angle—neatness is critical for legibility.

• Revise and turn the pencil often to maintain sharp, crisp lines.

5. Complete the Drawing

• Make sure the remainder of the boom (if visible) and any side arms are drawn without overlapping or obscuring the fixture symbols.

• Double-check that all heights, unit types, and labels are clear.

• Remember to include a symbol legend on your plot for all units/drawing conventions used.

Drafting Tips and Best Practices

• Use precise tools: Always draft with a sharp pencil, quality straight edge, triangles, and scale ruler.

• Fixture Spacing: On booms, it’s common to place units 9in apart (center-to-center) due to limited vertical space—but check production needs.

• Clarity over complexity: Omit drawing unnecessary pipe length—focus on labeling exact heights.

• Annotation: Clearly indicate ‘AFF’ (Above Finished Floor) for side arm placement.

• Check your work: Compare plotted positions with real-world rigging constraints.

Tools You’ll Need

• USITT-approved symbol template or stencil

• Triangles (preferably a 45-degree for crosshatching)

• Mechanical or wooden drafting pencils (keep them sharp!)

• Scale ruler, T-square, or parallel bar for straight lines

• Drafting paper (with or without a grid)

• Eraser for clean corrections

Why Hand-Draft Booms?

Hand-drafting booms develops spatial awareness, attention to technical detail, and a working knowledge of how side lighting is planned and executed in real venues. These foundational skills are transferable to digital drafting and help you communicate better with electricians and riggers on the job.

Pro Tips & Further Resources

• Always consult official USITT symbol guides and layout conventions for consistency.

• Reference your institution’s or production’s standards for boom labeling and notation.

• For more detailed tutorials, visit StageLightingPrimer.com and HSTech.org.

• When in doubt, ask your crew chief or designer to double-check your plot’s clarity!

AI was used to convert the video transcript into this blog post.