Help! I Can't Math

by Richard Cadena

Don't tell me that you are just aren’t good at math. I won’t buy into that. On the other hand, if you say that you’re not interested in investing the time and effort to polish your math skills, okay, I get it. Math is not for everyone. But unless you have a learning deficiency like dyslexia, you can get good at math if you’re willing to invest the time and energy. Here’s how.

If you really want to understand your craft as an electrician or technician, then you need some decent math skills. The math is not hard if you practice it. Ohm’s law and the power formulas are just basic algebra. If you break it down into small steps, it’s really simple.

1. What is the question? That may seem like a trivial step, but it’s so important to identify the unknown variable. Write it down and make sure you know the units of measure. For example, if you’re trying to figure out the current draw for a particular fixture, then the unknown variable is the current I, and its units of measure are amps. The reason you should know the units of measure is because that sometimes can give you a hint about how to solve the problem. If, for example, the unknown variable is speed, its unit of measure is miles per hour. You can literally solve the problem by dividing the number of miles traveled by the number of hours it took.
2. What do we know? Identify the knowns or givens by writing down everything we know or are given. For example, if we’re trying to figure out the current draw for a particular fixture, we can look up the specs online and write down what we’re given, which is usually the voltage and the power in watts. Sometimes the specs include the power factor too.
3. Which formula should we use? Write down the formula or formulas for solving the problem. In our previous example (solving for the current draw), we will write down the power formula, but we need to know whether to use the single-phase power formula or the 3-phase power formula. If we’re trying to calculate the current draw for a single fixture, we’ll use the single-phase formula, but if we’re calculating the current draw for several fixtures in a 3-phase system, we’ll use the 3-phase formula.
4. Calculate the answer. Be careful to enter the right values for the knowns.
5. Evaluate your answer. Just take a look at the answer and ask yourself if it makes sense. For example, if you’re trying to figure out the current draw of a 2000-watt fixture at 208V and you get an answer of 961 amps or 0.961 amps, you should immediately suspect you made an error.
6. Double check your work.

Once you practice these steps and get really good at them, they become second nature to you and then you no longer have to think about them, they just happen like the moon follows the sun.