by Jeremy Sexton
It can be confusing when looking for equipment and trying to decide if it can be used in a specific facility. What’s the difference between 208 volts, 220 volts, 230 volts, and 240 volts? And what’s three phase power all about?
Voltage variances
Let’s start with voltage. The numbers (208, 220, etc.), indicate variances in the voltage levels of the power supplied to a facility, and how the transformers are connected once inside. Theoretically, they are all slightly different. However, these voltages are close enough that they can all be part of the same voltage class. You can compare voltage to pressure in a plumbing system. It’s what determines how hard the electrons are “pushed” through the circuit. Small variations can change the speed of the flow but will generally still allow the same work to be done.
Three phase power
Three phase power utilizes three “legs” that ensure the voltage at any given time is never zero. When compared to single phase voltage, this means that it requires smaller wire and typically generates less heat than a single-phase power source that’s doing the same work. When asked which is better for equipment, I always recommend using three-phase power. The wires are smaller, the fuses are smaller, and in my 20+ years of experience with industrial equipment, three-phase motors just last longer. Single-phase motors will normally require capacitors to start, and these capacitors tend to fail long before the rest of the motor is done. They can be replaced, but this isn’t something you’ll have to deal with on a three-phase motor. It’s also noteworthy that once you step up to equipment with a motor larger than 15 HP, three-phase will be the only option. Keep this in mind when choosing a facility, especially if you plan to expand in the future.
Summary
In a nutshell, you don’t need to lose sleep over slight variations in voltage levels as long as they’re close enough for the equipment to work. How close does it need to be to work? That depends on the equipment, but most manufacturers allow 10% on equipment. If a motor is wired for 230V, and your facility has 208V, the manufacturer should be able to make a couple of adjustments and the equipment will work just fine. Check with the manufacturer for sure, but generally a 10% variance isn’t going to cause any problems as long as the appropriate wire size, fuses, and overload relay settings are used.
It’s good to have a broad understanding of voltage and electrical requirements but unless you’re a qualified electrician, you should delegate the task of wiring your new facility (or ensuring it’s compliant). Hiring a qualified electrician to review your facility ensures that you’re up to code and have the correct voltage for the machinery you’re planning to install. Most manufacturers will request that you have your equipment installed by an electrician before they send someone out to train the operators.
Take a minute to talk to your equipment supplier about the voltage requirements and make sure your facility meets or exceeds them before buying. If not, you may have to upgrade before you can operate the equipment.
