Estimators should obtain weight data on special equipment. Time studies for installations on hours per pound are not consistent. The estimator should develop criteria using job experience data for specific equipment. Equipment manufactures are a good source for labor requirements on special equipment. An Occupancy adjustment factor should be considered to compensate for the excess labor required when working in occupied areas.
Duplication occurs when multiple installations of like products result in saving installation time.
Fixtures in the same concentrated area, parallel conduit runs and multiple conductors in a raceway are all examples of possible deductions for duplication. My pet duplication is multiple conductors in a raceway. Most labor units that you see are for one conductor in a raceway. Most contractors will admit that feeders are where they make their biggest profit, and here is a good reason for it. Project management is the answer.