Estimating, Safety, and Project Management
Estimating
The estimate is built from a quantity takeoff against the plans: device counts, fixture counts, linear footage of raceway and cable, panel and gear counts, and equipment. Apply labor units (hours per item or per hundred feet), then multiply by a fully burdened labor rate that includes payroll taxes, insurance, and benefits, typically 25 to 40 percent on top of base wage. Add material waste factors, permits, equipment rental, subcontractor quotes, and indirect overhead. Then add profit.
Safety
Construction electrical work falls under OSHA 29 CFR 1926, Subpart K. Temporary wiring must be protected, receptacles on construction sites require GFCI protection or an assured equipment grounding conductor program, and lockout/tagout is mandatory before working on energized equipment. Also know approach distances to overhead lines, fall protection at 6 ft, the 4-to-1 ladder set rule with 3 ft above the landing, and protective systems in trenches 5 ft or deeper.
Project management
Sequence matters: underground and rough-in before cover, inspections before concealment, trim-out and energization last. Track submittals, RFIs, change orders, as-builts, punch lists, and retainage. Change orders must be priced and documented before the work proceeds.
The classic trap: markup versus margin
Contractors who multiply cost by 1.20 to get a 20 percent margin actually achieve only 16.7 percent margin. Gross margin is a percentage of selling price, so divide by the complement.
Worked example
Material is $8,000 and labor is $4,000, for a total cost of $12,000. For a 20 percent gross margin, price = $12,000 / (1 - 0.20) = $15,000, giving $3,000 profit (20 percent of price). Multiplying $12,000 by 1.20 would give $14,400, only a 16.7 percent margin.