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Estimating and Bidding

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August 23, 2021

Welcome to the world of successful contracting tips. Each month we will be covering issues pertaining to profitably running an electrical contracting firm. My new column will focus on everyday nut-and-bolt issues. Topics will range from crucial do-or-die situations to the little problems that gnaw at you beginning on your commute home.

This first column explores a critical contracting procedure: estimating and bidding. Estimating is an extremely important and rather expensive part of the electrical construction business. Estimating determines the prices for which the company will sell its work. Because of the importance of this function, it is critical that a skilled and competent person perform the estimates.

The basic purpose of electrical estimating is to take a set of documents (a set of construction drawings and a book of specifications) and translate the information into a total dollar price for the work. This process is usually divided into three basic parts:

  1. The take-off
  2. Writing up the estimate
  3. Summarizing the estimate

The process of “taking off” the job is literally “taking” the information “off” the plans and transferring it to separate sheets. The estimator interprets the graphic symbols on the plans and translates them into words and numbers, which can then be processed.

In writing up the estimate, the estimator transfers the take-off information to special sheets, assigns both material and labor prices to each item and totals these prices on each sheet.

In the summary (Fig. 2), the estimator adds all the pricing sheets to give a total cost for the material and labor for the project being estimated. Any other costs that will be required for the project's completion, overhead for the maintenance of the company's internal operations and profit must also be included to determine a final selling price.

The basic purpose of estimating is to get from the plans to the price. Remember that the quality of any type of electrical estimating is dependent on the skill, diligence and judgment of the estimator. A set of labor units or an estimating technique that was divinely created would not assure that good estimates would be turned out by an estimator who lacks the skill or patience to use them properly.


The itemized estimate is the standard of the industry and has been for many years. It requires the continual use of labor units. These units represent the amount of time that should be required to install each item during a normal installation. These units are shown as hours per unit or hours per foot, as the case may be. For example, EMT conduit, under normal circumstances, will be installed at the rate of 0.02 hours per foot. (Note that this is the labor required for installing the conduit only, and that the required connectors, couplings and straps are labored separately.) No. 12 wire can be expected to be installed at a rate of 0.005 hours per foot.

It is also important to note that the estimator must use his or her own good judgment, developed through experience, to determine when a specific installation is significantly more difficult than the average. In such instances, the labor units for that particular item or items must be increased. Usually, an increase of 20% to 30% is enough, but some very difficult circumstances require even higher labor units.

Itemized estimating is the process of itemizing and pricing every piece of material that goes into an electrical construction installation in order to determine the cost of that installation. The very nature of this process makes it lengthy and difficult, especially when you consider that about 15,000 different items of electrical materials are commonly used. But regardless of the difficulty, the itemized estimate is the surest way to get a complete and accurate list of materials that will be required for any particular installation. No type of estimate is quite as reliable as a well-prepared itemized estimate.

As just stated, itemized estimates are difficult to prepare. In order to do one both thoroughly and efficiently, the estimator must follow a careful procedure. First the estimator should have a quiet and well-lit area to work in, free from distractions as much as possible. The estimator must then follow a step-by-step procedure to assure that he or she has taken all the required information off the plans and transferred this information to a pricing sheet where it can be accounted for.


The procedure for preparing an itemized estimate is as follows:

  1. Review the job you are about to estimate, including plans and specifications for the installation. Get a good understanding of exactly what the building is going to be like. Review the entire set of plans and specifications, not just the electrical pages. The first section of the specs, usually called “General Conditions,” spells out exactly how the job will be run, how payments will be made and how disputes will be settled. This first section of the specifications is especially important. Section 15 of the specs, which governs the installation of the mechanical equipment, is also important, because the electrical and mechanical trades have a great deal of overlap in their work. Go over Section 16 completely and thoroughly, for it is the section that explains the specific techniques and materials required for the electrical installation.

    Fig. 1 on page 18 shows a pre-bid checklist that you should fill out as you review the plans and specifications. The items shown on this checklist are the most important considerations to the estimator in pricing the installation.

    Take special care in reviewing the site drawings, which may contain expensive details of the electrical installation that are not specifically shown elsewhere. Often you will find site lighting, service runs and remote devices on these sheets. Review all the plan sheets, but give special attention to the sheets that show work with which your work must interface, most typically mechanical and ceiling work.

    During the pre-bid checklist stage, you should ask yourself all of the most important questions as you prepare your estimate. You should also go over these questions as you price and review your estimate as well. Use this list as a checklist, to make sure that you have covered all the expenses that you will incur during the job you are estimating. Almost all the mistakes made in itemized take-offs are omissions. Therefore, a careful review of the plans and specs and repeated reference to a good checklist are extremely important.

  2. Do a take-off of the lighting fixtures. Starting on the first electrical sheet, completely color in and count every lighting fixture. Do one type of fixture at a time, and use a hand-held counter. Check the fixture schedule on the plans to make sure that you understand and count every type of fixture. Write down all the totals on a separate sheet of paper. Leave plenty of blank space on this tabulation sheet. During the following stages of your take-off you are bound to find stray light fixtures that you missed the first time through.

  3. Do a take-off of all the wiring devices.

  4. Do a take-off of the one-line diagram. The one-line diagram shows the power distribution for the project you are estimating. Carefully make a list of each item of equipment that is shown on this diagram and write a good description of each item. Next, you must do a good take-off of the various feeder circuits that bring power to these pieces of equipment. Each feeder shown on the one-line diagram should be recorded and completely colored. All the equipment shown on the one-line diagram should also be completely colored in. As you take off all these feeders, you will have to find the various items on the plans in order to determine the distances between them. Measure the distances between the items with a rotometer, also sometimes called a “map reader.” Make sure that you are using the right scale for each drawing, and be sure to include the vertical portions of the feeder runs, which cannot be shown on two-dimensional drawings.

  5. Do a take-off of all the branch circuitry, including raceways and wire. This is the most lengthy part of the take-off procedure, although it is not exceptionally difficult. Starting with the smaller sizes of raceway, color in each raceway and wire combination with a separate color. For instance: ½-in. EMT with two No. 12 THHN wires could be light blue, ½-in. EMT with three No. 12 wires could be bright red, ½-in. EMT with four No. 12 wires could be brown, and so on. By the time you run out of colors (assuming you have a good set of colored pencils), you should have indicated all the common types of raceway and wire combinations and can simply note what the remaining raceways are.

Next, with your rotometer measure the length of all the runs of each type of raceway and wire combination. As you measure these runs, keep your counter in your other hand and click it every time the run you are measuring goes vertical, either up or down. When you finish all the runs of one color, write down the total measurement and add to it the vertical distances as well. This will give you the proper total for this combination of raceway and wire. The correct vertical distances for each project can be calculated by looking at the wall cross sections on the architectural plans and the outlet mounting heights shown on the electrical plans.

After you finish taking off every type of raceway and wire combination shown on the plans, you should be able to produce a list that includes all the quantities taken off the plans. All the quantities should be written down and then totaled at the bottom of the sheet.

When these totals are transferred to an estimate sheet for the final pricing, it is usually best to increase the quantities of the conduit slightly (2% to 4%) to account for waste. You should also increase the quantities of wire about 5% to account for the wire that must be left hanging out of boxes or that is wasted.