Fundamentals Of Wire Use Estimation


By Lee Distad

For years now it’s been the trend for AV specialty retailers to move into custom installation. While in some ways it’s a natural fit, in others there’s a bit of a learning curve. Few AV retail guys have a background in design, installation, project management, or any other industrial skill sets.

As a result, it’s a common pitfall for AV dealers-turned-hybrid-AV retailers/installers to hemorrhage money through inefficient installation practices. Time is money, and as some dealers soon learn, money is also money. And going about things the wrong way will cost you too much of both.

Much installation work needs to focus on ensuring that tasks are being done efficiently, and that design work supports an efficient install schedule. One key task is accurately estimating the wire that a project will require.

It’s important to bring adequate amounts of wire for the job. Failing to do so will lead to delays and wasted time scheduling extra workdays. That picks insidiously at the project’s profit margin. On the other hand, overestimating wire requirements means that inventory dollars are tied up in half-used spools of wire. Until you find a home for it in other jobs that also costs money.

So, how do you estimate your project’s wire usage? Start with the scale plans of the jobsite on your desk, with the equipment locations marked, an architect’s scale, and a notepad. Measure the right angles it takes to reach from Point A to Point B. For each move from one floor to the next add nine feet for the vertical measurement. Then add a few percent extra to your estimate, just to be safe.

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What’s a good percentage to add to the estimate? You can add five percent and then modify it as you learn from your projects. Ten percent is good, but probably excessive. My old boss and mentor confided while training me that he uses seven percent because “if you end up explaining it to the customer, it sounds like you put some thought into it.” The reason for building wiggle-room into your estimate is to compensate for the difference between the “as drawn” and “as built.” Or as I like to call it, “Hey, this structural beam wasn’t on the drawings! We’ll have to go around it.”

From there, calculate out all the required lengths for each cable type in the installation, and order what the project requires. After the pre-wire is completed, have a meeting where the designer, project manager and lead installer compare what was estimated and what the installers actually pulled. If the two numbers are close, HOORAY! If not, learn and move on.

Efficiency doesn’t make money (making money makes money, as my old boss used to say), but it does the next best thing: It saves you money.

Lee Distad is a rAVe columnist and freelance writer covering topics from CE to global business and finance in both print and online. Reach him at