Fixture Schedule Quantities Disagree With the Plan Count
A 6-story office project has a lighting fixture schedule generated from the model. The schedule shows 1,240 fixtures total. The electrical contractor's takeoff from the issued PDFs shows 1,198. The discrepancy is concentrated on levels 3 through 5, where the design team recently revised corridor lighting from 2-lamp to 4-lamp troffers and added emergency battery units. The schedule was created before the revision and uses a filter by 'Type Mark'. Some revised fixtures were placed as copies of an existing family with the Type Mark edited manually rather than by creating a new type.
1. Explain the likely causes of the quantity discrepancy and how the schedule should be structured to prevent recurrence.
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Two causes are likely. First, the schedule was created before the corridor revision and may not include newly created types if the schedule's filter or category scope excludes them, or if the schedule is filtered by a Type Mark value that the new types do not carry.
Second, editing Type Mark manually on instances does not create a new type. Type Mark is a type parameter, so editing it on an instance changes the type for all instances of that family type, or in some cases the edit is not applied as intended. This produces fixtures that look revised in the plan but report under the old type in the schedule, or vice versa, inflating or deflating counts.
Fix the schedule by removing filters that depend on manually edited values, grouping by Type Mark and Type Name, and adding a count column. Create proper new types for the 4-lamp and emergency variants rather than editing instances. Add a QA step comparing schedule totals to a plan count by level.
2. The contractor's count is lower than the model. How would you reconcile the two counts and what would you issue?
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Reconcile by level and by type. Export the schedule to a spreadsheet with columns for level, type mark, type name, and count. Have the contractor provide the same breakdown from the takeoff. Diff the two by level and type to isolate where the 42-fixture difference sits.
Investigate the levels 3-5 corridor specifically: check for fixtures placed in linked models or design options that the schedule does not capture, fixtures in worksets not visible to the contractor's PDF set, and duplicate instances stacked at the same location. Also check whether emergency battery units were modeled as separate fixtures or as a type parameter, which changes the count.
Resolve each discrepancy with a documented decision. Then issue a corrected schedule with a revision cloud and a delta note, and update the drawing notes to state the schedule governs. Provide the spreadsheet as a backup to the PDF so the contractor can verify the count.