All About Motor Disconnects—PART I

Choosing the right type of motor disconnect seems simple enough—until you consider all the options.

With all the different motor disconnects on the market, the best choice for your application isn’t always obvious. But if you follow a few simple specification steps, you’ll end up with the right disconnect switch every time. Over the next few blog posts, we’ll examine those steps in detail, starting today with the importance of the operating environment.

Evaluate the operating environment. You likely pay plenty of attention to the electrical characteristics of a motor disconnect. That’s a good thing, but also important is to carefully evaluate the disconnect’s operating environment. This step is often overlooked. Yet, it’s important because the operating environment will determine what type of housing material will work best in your plant or shop floor.

High-quality motor disconnect switches are now available in both metallic and non-metallic. Our products use UL Listed metallic and non-metallic enclosures, both with a NEMA 4X rating, so they offer watertight protection for harsh manufacturing environments. In fact, all NEMA 4X enclosures, by definition, should be able to withstand challenging operating conditions—including those with corrosive chemical exposures and caustic cleaning substances.

If both metallic and non-metallic can meet the same NEMA rating, then how do you choose? Typically, the type of manufacturing operation will make the choice clear.

Where stainless steel shines. Metallic enclosures, stainless steel in our case, are increasingly favored for areas with the potential for direct food contact. One reason involves stainless steel’s tolerance of repeated washdown cycles. The other reason is that food processors prefer metallic enclosures in production line areas since metal detection systems can pick up foreign matter if there is breakage.

Metallic enclosures also have better impact resistance, so high-traffic and end-of-line applications in packaging, manufacturing and pharmaceutical facilities often use stainless enclosures.

High-performance polymers. The vast majority of motor disconnect applications are well served by disconnects with a non-metallic enclosure. These polymer housings have a lot going for them:  Non-metallic housings generally cost less than a comparable metallic housing.  Non-metallics also cost less to install—in part because they are easier to punch and rough-in for fittings and conduit than metallic boxes.

So unless you need stainless for a specific food processing area, or for impact resistance, polymer housings will likely offer all the performance you need for less money.

Keep in mind, however, that not all non-metallic disconnect switches are created equal. While any NEMA Type 4X disconnect has a watertight rating, the type of polymer used for the enclosure has significant performance consequences when it comes to weather, flame and impact resistance. We make all our enclosures from a very high-performance polymer that is UV stabilized and has a UL 94 -5V flame rating. Our enclosures are also UL Listed, which indicates that they have passed rigorous impact and bending tests.

More on motor disconnects. Stay tuned for more on motor disconnects or sign up below to receive updates by email. In the next few blog posts, we’ll dig into the best uses for different types of switches, including 6-pole, double-throw and emergency switches.