TABLE OF CONTENTS Example Voltage-Drop Calculations
The Christoffer Tables (tm) were designed in a unique fashion to give you a quick and easy way to do your calculations simply by reviewing the tables and using a four function calculator. In some cases you don't even need to use a calculator, all you have to do is look at the appropriate table and copy the answer. To get a precise answer or get the actual volts drop, for example, you will only have to do simple multiplication and division. That's it! Remember, there are two types of tables used for conductor calculations that are explained below. The following examples will give you enough direction in these calculations to do almost any voltage-drop study.
1 - "Voltage Drop Factors per 1000 Ampere Feet." This first type of table, shown in example #1, gives voltage drop factors for three-phase, single-phase line to line and single-phase line to neutral circuits, each on separate pages. These tables are extremely flexible and allow you to calculate the voltage drop for virtually any circuit through 600 volts. They are also categorized by the type of conduit and whether the conductors used are copper or aluminum.
Example #1: A three phase, 240 volt, 40 amp load at 80% power factor; #6 copper installed in 180 feet of galvanized rigid conduit. What is the actual drop in volts? What is the actual drop in percent? If the distance increases to 350 feet,...
