Estimate your commercial electrical installation costs with our easy calculator. Buyers typically pay a broad range for replacing a distribution box, driven by box size, amperage, wiring runs, and local labor rates. This article outlines the cost factors, price ranges, and practical budgeting advice for a U. Whether it's an office buildout or a warehouse renovation, this calculator provides a good starting point for planning. The Suggested Retail price column, also referred to in the industry as the third column, end column or best column are the manufactures' most current published prices. Average markup 30-50% on materials.