Electrical calculators
Six calculators for the work between the takeoff and the bid. Four are NEC checks: how many conductors and devices fit in a box, which conduit size a group of conductors needs, how much voltage a long run loses, and a building's Article 220 load. Two turn quantities into a price: an electrical estimate calculator and a construction cost estimator. All run in your browser, and show the tables or formulas they use. The load, estimate and cost worksheets also export to CSV.
Where each calculator fits in a bid
Most of these come after the count. Once the takeoff tells you how many receptacles, fixtures and panels a job has, the NEC checks catch the places where the drawings leave a sizing decision to the contractor. Start with the load calculation worksheet on design-build work, or when the panel schedules are missing, so the service and feeders you price have a basis. Long feeders and home runs go through the voltage drop calculator, and when the wire gets bigger, the conduit fill calculator tells you whether the pipe has to grow with it. At multi-device locations, the box fill calculator shows where a standard box turns into a 4-11/16 in box with a ring.
Pricing comes last. The electrical estimate calculator multiplies counts by your material prices and labor units, which suits a small job or a change order. The construction cost estimator is for work priced by line item rather than by device, and is the place to settle markup against margin. For a full bid, the estimating templates keep the same math in Excel and Word, and the guide to electrical estimating walks through the process from plans to proposal.