Motor Disconnects At A Glance

Motor Disconnects At A Glance

Motor disconnects are more than simple on-off devices. They increasingly offer additional control functions, such as test-off-run switches. Motor disconnects can also pack multiple devices into one enclosure, saving space and cost while allowing you to address different application requirements. Here's a quick visual overview of what today's motor disconnects can offer.

Motor Disconnects For VFD Applications–PART III

SwitchIn the right applications, variable frequency drives (VFD) will improve the control and reduce the energy costs of your AC motor-driven equipment. To install a VFD safely, however, you may need to reconsider the type of motor disconnect you use.

The traditional knife-blade style of disconnect, while compliant with the National Electrical Code (NEC), is not the best choice for modern VFD applications. The reasons why are both physical and electrical.

From a physical standpoint, the traditional NEMA-style blade disconnects are too bulky for IEC installations, which often group or combine motor controls and disconnects in a shared enclosure or in limited spaces. In these applications, the best alternative is a compact rotary disconnect.

The use of rotary disconnects, in non-metallic or stainless steel enclosures, continues to grow in popularity as more and more machine builders and OEMs adopt IEC devices.

From an electrical standpoint, VFDs require motor disconnects with an auxiliary contact that can provide crucial early break functionality. This contact signals the drive before disconnecting the motor, giving the drive time to power down in a controlled manner before the mains open.

Plenty of disconnects, both blade- and rotary-style, offer an auxiliary contact. But disconnects are not all created equal when it comes to protecting expensive VFDs.

For one thing, auxiliary contacts have speed differences based on their actuation methods. Cam actuated versions provide fast and predictable early break switching. Our onboard cam-actuated auxiliary contacts will provide a minimum, repeatable time gap of 20 ms between the opening of the auxiliary and the opening of the mains. This repeatability and speed provide an advantage over conventional auxiliary contacts with mechanical linkages whose actuation speeds can vary based on how slow or fast the switch handle is operated.

For another thing, auxiliary contacts aren’t always included in the price of the base disconnect. In our case, auxiliary contacts are included as a standard feature. Both auxiliary contacts and early break capability can be options with other manufacturers at an added cost.

Read Part I and Part II of this series to learn more about how to select the best motor disconnect. Or download our catalog to see specifications for our full line of motor disconnects.

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Video – Superior Washdown Performance

If you need a compact power distribution solution for washdown or cleanroom use, check out our SpecMAXX Series. All enclosures feature a sloped roof that facilitates runoff of liquids and cleaning residue. A drainage channel impedes harborage of contaminants for use in a wide range of applications––from meat and dairy processing, to pharmaceutical plants. In addition to superior washdown performance, SpecMAXX also offers many custom design features.


Understanding The Options For Motor Disconnect Switches—PART II

SwitchOpen any catalog of motor disconnect switches, and you may be overwhelmed by all the different design options. Does your disconnect need to be fusible? What is the best type of enclosure for your application? Is it a 1Ø or 3Ø switch requirement? What HP is needed? Do you need an installed pilot device?

The list could go on and on, and for good reason nowadays. Far from being simple ON-OFF devices to meet LO/TO requirements, motor disconnects increasingly have to meet challenging electrical or installation requirements, and in many cases, you may need a specialized switch to meet those requirements.

In this segment on our motor disconnect series, we’ll examine some key options and customizations you may require when specifying a motor disconnect.

Electrical Options
As you configure your disconnect, it’s important to keep the following electrical options in mind:

  • Fusible or non-fusible. Your application will likely determine if the switch should be a fusible or non-fusible type. Fusible switches have a fuse provision in the switch and enclosure assembly, enabling you to open and close the circuit while providing overcurrent protection. Non-fusible switches do not have an integral fuse option and provide no circuit protection. Quite simply, does your need require fuse protection at the switch, or is there upstream protection to eliminate this need at the switch? MENNEKES offers both non-fusible UL508 or fusible UL98 disconnects.
  • Pole and throw options. Is the voltage requirement 1Ø or 3Ø? This will determine the number of poles to match the voltage configuration and related HP rating. Most industrial requirements use 3 pole switches, but MENNEKES also stocks 6 pole disconnects in both non-metallic and stainless enclosures. These are a perfect disconnect means for two-speed or reversing motors. Off-the-shelf availability and compact size make them especially useful for motor control applications. As an added option, we offer 6 pole double throw disconnects with a center OFF position to transfer loads from one power source to another.
  • Pilot device.  Do you need a pilot device as well as a disconnect in the same enclosure? Normally a separate enclosure is required to mount these devices. With MENNEKES disconnects, you can customize your disconnect and add a pushbutton, selector switch or pilot light in the same enclosure. We stock many 22.5mm and 30mm pilot devices, or we can assemble to your specifications.

Enclosure Options
When it comes to housing your electrical devices, the more installation and design options you have, the better. Some of the key enclosure options include:

  • Extra space. A little extra space in the box can make it faster and easier to install. MENNEKES stocks many disconnects in an extra-large enclosure. This also allows for factory installed or on-site customizations.
  • Material options. Disconnect enclosures come in both metallic and non-metallic versions. Both have their advantages. Metallic boxes maximize the impact resistance for high-traffic and end-of-line applications in packaging, manufacturing and pharmaceutical facilities, while non-metallic enclosures generally have a lower installed cost and increase customization options. Our non-metallic AMAXX products, for example, let you freely combine multiple disconnects and related devices in a single enclosure, saving time, installation cost and space.
  • Environmental resistance. The type of enclosure will also determine which operating environments the disconnect can tolerate. Most food processing or wash down applications require Type 4X watertight enclosures to withstand cleaning agents. Our sloped-top stainless enclosures provide this protection and shed liquids and contaminants.

To learn more, refer to Article 430 of the National Electrical Code for additional information about how to properly size a disconnect switch for single motor and combination load applications. For more information on MENNEKES motor disconnect options, download our product catalog.

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Configure AMAXX Online

Designing power distribution centers just got a whole lot easier. Our new online configuration tool, which launches today, lets you configure standard and custom AMAXX® power distribution centers in just a few mouse clicks.

The AMAXX line consists of high performance non-metallic enclosures that can hold many different combinations of disconnects and receptacles—including switched-and-interlocked, GFCI and NEMA devices. AMAXX enclosures are available in one- to five-gang units, all UL listed.

Using the new configuration tool, you can build a standard or custom AMAXX power distribution center in less than a minute. The configuration tool can optionally submit an instant request for quote to a MENNEKES application engineer.

Try the new configuration tool now at

Configure AMAXX   

Wiring Devices For Global Server Equipment

With the explosion of cloud computing, there’s a growing need to run large numbers of identical servers in data centers around the world.

62334mLocalized data centers are a good thing from a computing standpoint, but they do create an often-­overlooked power problem: Server equipment designed for one locale can’t necessarily use the same wiring devices as servers designed for another locale.

Dual­-rated Solution. That’s where dual-­rated wiring devices come in. You simply buy one device that meets electrical standards for North American, European and other international markets.

For instance, we offer pin­-and-­sleeve plugs, receptacles and connectors that are culus Listed to UL 1682/1686 and CSA 22.2 181.1 Standards for use in North America and also have CE and VDE certifications for Europe and the rest of the world.

Looked at in terms of electrical requirements, a single dual-­rated device will support two different amperages—including 30/32, 60/63 and 100/125 amps. Common voltages for these devices are either 250V or the trending global standard of 240/415V.

Design details matter. Dual­-rated devices are becoming increasingly popular, but not all of them are created equal. Like any wiring device, the design and construction details can make a big difference.

Take installation cost, for example. Our dual-rated devices have a threaded NPT cable entry for direct installation of flexible conduit and armor cable fittings. This design detail eliminates the need for adaptor fittings, saving installation time and cost.

Other design details include:

  • Standard UL Type 4X and IP 67 rating.
  • IP 44 weatherproof devices available as an option.
  • Flame rated (UL V­0) housing on 60/63 and 100/125 amp models.
  • Elastomer finish to ease handling and installation.

You can learn more about dual-­rated plugs, receptacles and connectors in our catalog.

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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.

Customizable Stainless Steel Power Distribution Systems

SpecMaxx-3Modular power distribution systems typically feature polymer enclosures, which are lightweight and easy to install. Sometimes, however, the application or environment calls for stainless steel enclosures. That’s where our SpecMAXX system comes in.

Intended for industrial and commercial use, SpecMAXX features 304 stainless steel, UL-approved enclosures with 15-degree sloped roofs that shed liquids when cleanliness counts. Shrouded side walls protect cover mounted devices from impact so the SpecMAXX can work in the most demanding environments.

SpecMAXX’s added protection doesn’t come at the expense of design flexibility. The system lets you choose from three different enclosure sizes and a complete range of electrical devices. Examples include:

  • Pin and sleeve, NEMA and GFCI receptacles
  • Switched and interlocked receptacles
  • Multiple disconnect switches
  • Breakers or fusing
  • Blank plates for field customization

Lower Costs And Faster Lead Times. Using SpecMAXX reduces the time and costs necessary to source, assemble and mount your power distribution system. In addition, this system gives you the flexibility to customize based on your needs.

Other benefits include:

  • Generous wiring space
  • One piece punched gasket for watertight seal
  • Sealed fixing holes
  • Removable module plates with captive hardware and retention straps


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Mixing Power and Control in a Single Enclosure

Industrial plants and machines often have complex power distribution systems, and the reason why is simple: Machine builders and engineers typically use multiple enclosures when combining low-voltage wiring devices with control.

The truth is, however, that you can safely mix low-voltage power and low-voltage control and communication devices in one enclosure as long as you follow good design practices.

AMAXX System

  1. Select The Correct Wire Insulation Rating. First, make sure all the wiring insulation in the enclosure corresponds to highest voltage device, i.e. 600VAC. For example, if you want to pack a low-voltage data port and 480V motor disconnect switch into the same enclosure, go ahead. Just make sure that data port cables have the same insulation rating as the voltage of the motor disconnect switch conductors. Keep in mind that you can buy shielded Cat 6 cable rated up to 600V, so getting the wiring right in this type of mixed installation isn’t a big deal with a bit of planning.
  2. Pick the Right Enclosure. If you want to use a single enclosure for mixed-voltage components, you’ll want to look at modular power distribution systems. These will let you freely customize the enclosure for your application. With our AMAXX system, for instance, you can easily pack a 480V receptacle, a 250V motor disconnect switch, a data port and a 120V convenience receptacle into a single modular enclosure. Normally, that many wiring devices would require two or even three separate enclosures.

Mixing different low voltages within a single enclosure may sound like a big step if you’re used to traditional wiring. But done right, the payoff from consolidating enclosures can be huge. Total wiring costs—including materials and labor— can drop by 20 percent or more once you start reducing the number of electrical enclosures on typical installations.

You can learn more about modular power distribution systems here.