SQUARE-D DU321RB AC Disconnect, NEMA3R, 30A 240VAC, 3-Pole Unfused
General duty safety switches are designed for residential and commercial applications where durability and economy are prime considerations. Typical loads are lighting, air conditioning and appliances. When equipped with fuses, over-current and short circuit protection is also available. The switches are also suitable as service equipment when equipped with a factory-installed neutral assembly or a field-installed equipment grounding kit.
General duty switches feature:
30–600 A rated for application loads upto 240 V
Up to 100 kA SCCR, utilizing appropriately rated Class R Class J or Class T fuses or fuse kits
Horsepower rated for motor applications
Type 1 and 3R enclosures
CSA certified , File LL-89067
Meets or exceeds NEMA KS1-1990
Tangential combination knockouts 30–200 A
Spring reinforced plated copper fuse clips
Insulated, bonded solid neutral assemblies (standard in fusible switches)
Quick-make, quick-break operating mechanism
Cover padlock hasp and handle lock “OFF”
Setting the standard for perfomance, quality and reliability in today’s commercial and industrial applications
First introduced in 1907, Square D safety switches have a long history of leadership in safety and performance. Since then, we have pioneered many innovations to help maximize the lifetime value of our safety switches.
Safety switches play a crucial role in today’s commercial and industrial settings. They isolate power in daily activities and provide an effective way to interrupt power in an emergency. Two primary applications for safety switches are as a lockout on sight disconnect and as a circuit isolation device.
Three Times the Life — Three Times the Value
The performance of safety switches is important to the safe and profitable operation of many industrial settings. In addition, requirements from organizations such as the Occupational Safety and Health Administration (OSHA) have increased the use of safety switches in many commercial and industrial facilities.
The useful life of a safety switch is less than two years based on NEMA KS-1 life test requirements, in lockout/tag out applications where a switch is operated just once per hour, 24 hours a day, seven days a week. For switches in these high-use applications, durability is key.
Square D safety switches provide significantly higher levels of mechanical endurance than NEMA KS-1 require. This translates to improved reliability in a production environment. In fact, the standard for the design life of Square D F-Series safety switches is a minimum of three times the NEMA requirement. No competitor comes close to the performance offered by Square D safety switches.
Designed for the Best Performance
A key performance benefit of the Square D safety switch is its ability to break load.
A locked motor can draw six to eight times motor full-load current. In an emergency situation, it’s important to have a switch with enhanced load break capability. A key element
of Square D safety switch is their blade and jaw construction designs built to easily manage heavy motor loads and arc interruptions.
Square D safety switches are above all else built to increase safety.
Visible blades are an important feature, and they must be visible in real-world conditions to visually verify that the down-stream circuit is de-energized. Our switch blades are easily visible, even in the less than ideal lighting conditions where electrical equipment is often installed.
An optional view window adds another degree of safety through visual verification of switch position without the need to open the door.
In addition, the design of the Square D safety switch includes an oversized arc suppressor, a key feature in the ability of the switch to break the load by effectively attenuating the arc for a clean interruption.
Designed for Long-Term Durability
Rugged construction and corrosion protection provide the industry’s longest lasting switches. Galvannealed steel in all single-throw Type 3R and 12 enclosures provides superior corrosion protection.
Type 4X seam-welded enclosures help extend equipment life by providing excellent environmental and corrosion protection without the use of a silicone sealer, which can be incompatible with some manufacturing processes.
Managing temperatures inside the switch is essential to providing greater service life. Square D safety switches feature more copper than other switches available on the market today. This larger amount of copper is one of the reasons Square D safety switches have lower operating temperatures.
Heat is not the only factor that impacts switch life. The enclosed operating mechanism design of Square D safety switches reduces the amount of dust and other contaminants that shorten the mechanism’s operating life.
A Full Range of Accessories
Square D safety switches feature a complete offering of accessories, available either factory installed or field installable. Factory-installed options include key interlocks, nameplates, push buttons and optional safety colors. Field-installable accessory options include neutral kit, ground lugs, electrical interlocks, Class “R” fuse rejection kits,
compression terminals and conduit hubs.
Our time-saving design features make installation quick and easy.
Square D safety switches feature quick-release cover latches that are easier to operate than screw-fasteners. On Type 4X and Type 12 switches, this design feature ensures a better
gasket seal — a critical feature in adverse operating conditions — than is available with designs that rely on screw-fastened covers.
Tangential knock outs enable easier installation of conduit, without the need for costly, timeconsuming offsets and bends.
Advanced maintenance features extend switch life and reduce down time, saving both labor and material costs. The Square D safety switch modular design allows the replacement of all interior worn or damaged components.
Field-replaceable components such as interior line bases, load bases and mechanisms are available. In addition, handles and lockplates are also replaceable if they are damaged or vandalized.
In addition, Square D Type 4X and 12 safety switches come standard with fuse pullers, increasing the convenience and safety of maintenance. Fuse pullers are also field-installable on certain models.
Operation and Safety
Nothing is as important in the design of a switch as understanding how it will be used. To ensure Square D safety switches continue to meet the needs of commercial and industrial applications, products are engineered with the operational procedures and safe work practices of customers in mind.
Superior Handle Design
The Square D F-Series insulated switch handle is an industry exclusive. It is made from a high-strength polymer chosen for weather resistance, durability and impact strength.
The two-color position-indicating handle on heavy duty safety switches enhances operator safety by aiding in visual recognition of switch position from an angle or at a distance. The simple concept of having contrasting colors on the handle enhances the ability of the operator to determine quickly the position of the switch, even in low light conditions. In an emergency, it is vital that switch position be accurately recognizable. Plus, an embossed on/off marking is a permanent indication of the switch position and cannot be removed or vandalized.
Resolving lockout issues is a priority with major industrials. Square D F-Series safety switches have an extruded lockplate feature that helps prevent tampering with lockout devices. The lockplate opening is extruded to reduce the possibility of lockout devices being removed by non-authorized personnel.
With the use of the handle lockplate, the switch can be locked in the OFF position with up to three padlocks to comply with OSHA lockout requirements.
The safety switch can also be modified so that the switch can be locked in the ON position, if required by the application.
Heavy-duty dual cover interlocks are key
Safety features on single throw and double throw heavy duty switches. These prevent the opening of the cover when the switch is ON or turning the switch ON when the cover is open.
Qualified personnel can also defeat this feature allowing them to perform any necessary testing.