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Estimating Branch Wiring on Commercial Projects

If you track your estimates, you will find that the branch wiring is approximately 60% to 80% of the estimate in most commercial projects. On industrial projects, it may only be 5% – 10%.

It is a common practice among estimators to use an average foot per device. Let’s suppose you use an average of 15 feet when in reality the average was 18 feet per device. Three feet over on 15 feet is 20%. Therefore, you may be off 20% on 60% to 80% of the estimate

Branch wiring is usually considered all one-inch conduit or smaller in all systems. It would also include all cable wiring. Estimates are won and lost by how efficient the branch wiring is estimated.

Projects make money or lose money based on how efficient the branch wiring is installed.

Most estimators do not like estimating branch wiring because it is the most tedious part of the estimate. Therefore, the wise estimator will estimate branch wiring as accurate as possible.

Using an average length of conduit and wire or MC cable per device is an acceptable method if you have established an average length for the project you are estimating. Do not use the same averages for all types of projects.

When estimating branch wiring be sure to consider the following:

  1. Combining branch homeruns
  2. Install branch wiring in slabs where possible.
  3. Use the least expensive wiring method allowed by the specifications.

Conductors should be estimated with a 10% waste.

Therefore, focus on the branch wiring in your estimates. Accuracy in all systems will provide you will a solid estimate and consistency in the bid results.

Remember, estimating is expensive, poor estimating is costly, and quality estimating is profitable.