5 Common Mistakes in Electrical Takeoffs

Electrical takeoffs are among the most detail-intensive in construction. The sheer number of components, from conduit runs to individual devices, creates plenty of opportunities for error. Here are the five mistakes we see most often.

Mistake 1: Ignoring homerun wiring. Many estimators measure branch circuit conduit and wire but forget the homeruns back to the panel. On a commercial project with dozens of circuits, this can represent thousands of feet of wire and conduit that are not accounted for.

Mistake 2: Underestimating fittings and connectors. For every length of conduit, there are couplings, connectors, straps, and junction boxes. A common rule of thumb is that fittings add 30-50% to the cost of conduit alone. Skipping this creates a significant gap between your estimate and actual cost.

Mistake 3: Missing specification requirements. The electrical specifications often call for specific products, ratings, or installation methods that affect pricing. A spec that requires MC cable instead of EMT conduit changes the material cost dramatically. Always cross-reference the drawings with the specifications.

Mistake 4: Not accounting for height and access. Working at height costs more than working at grade. If your takeoff treats a 30-foot high installation the same as a 10-foot one, your labor estimate will be wrong. Factor in lift equipment, reduced productivity, and safety requirements.

Mistake 5: Forgetting temporary power and testing. Most electrical scopes include temporary power during construction and final testing and commissioning. These are scope items that cost real money and are frequently left out of estimates.