Siemens vs Square D MCC Buckets: A Head-to-Head Comparison
Siemens and Square D are the two most popular MCC brands in North America. When specifying a new MCC or evaluating replacement buckets, engineers and maintenance professionals frequently ask: which is better? The honest answer is that both are excellent platforms, but they have meaningful differences worth understanding.
The Contenders
Siemens Tiastar: Siemens' flagship MCC platform with a global engineering heritage. Known for robust construction and strong international presence.
Square D Model 6: Schneider Electric's premier MCC, descended from the legendary Square D lineage. The most widely installed MCC in North America.
Design Philosophy
Siemens Approach
Siemens designs with a global perspective. The Tiastar MCC follows IEC-influenced design principles even while meeting UL 845 requirements:
- Emphasis on modular, configurable bucket designs
- Strong integration with Siemens automation ecosystem (TIA Portal, SIMATIC PLCs)
- Global standardization (same platform available worldwide)
Square D Approach
Square D designs for the North American market first:
- NEMA-centric design philosophy
- Deep integration with Schneider Electric power distribution products
- Extensive installed base creates strong parts availability ecosystem
Component Comparison
Contactors
Siemens: Uses 3RT series contactors (IEC-rated). These are compact, globally available, and offer a wide range of accessories. IEC contactors are generally smaller than NEMA equivalents for the same application.
Square D: Uses 8536/8906 series NEMA contactors or Schneider TeSys series. NEMA contactors are larger, heavier, and typically more expensive, but include a built-in overload relay base and are rated with more conservative service factors.
Practical Difference: IEC contactors (Siemens) are more compact and less expensive per unit. NEMA contactors (Square D) are more robust and have longer contact life. For most applications, both perform reliably.
Overload Relays
Siemens: 3RB (electronic) or 3RU (thermal) series overloads. The 3RB electronic overloads offer comprehensive motor protection with network communication options.
Square D: LRD (thermal) or LR9 (electronic) series overloads. Schneider's electronic overloads integrate with their communication modules for smart MCC applications.
Practical Difference: Both manufacturers offer excellent electronic overloads with comparable features. The choice often comes down to which communication protocol your plant uses.
Circuit Breakers
Siemens: Uses Siemens 3VA series molded case circuit breakers. Available with thermal-magnetic or electronic trip units.
Square D: Uses PowerPact series (HG, JG, MG frames) molded case circuit breakers. Known for the Micrologic electronic trip unit.
Practical Difference: Both offer comparable interrupting ratings and features. Parts availability is excellent for both brands in North America.
Construction Quality
Siemens Tiastar
- Welded steel frame construction
- Powder-coat paint finish
- NEMA 1 standard (NEMA 3R, 12 available)
- Well-organized internal wiring layout
Square D Model 6
- Unitized welded frame construction
- Powder-coat paint finish
- NEMA 1 standard (NEMA 3R, 12 available)
- Dead-front design standard
Both manufacturers produce high-quality enclosures that meet UL 845 requirements. Construction quality is comparable, with minor differences in wiring accessibility and component layout.
Smart MCC Capabilities
Siemens
- Integration with SIMATIC PLCs via PROFINET, PROFIBUS, or EtherNet/IP
- Siemens MindConnect for IIoT connectivity
- TIA Portal engineering software integration
- Comprehensive diagnostics through 3RB overloads
Square D
- Integration with Schneider Electric PLCs or third-party via EtherNet/IP, Modbus TCP
- EcoStruxure platform for IIoT connectivity
- Advanced motor management through TeSys island technology
- PowerLogic energy monitoring integration
Practical Difference: If your facility uses Siemens PLCs, the Tiastar integrates more naturally. If you use Schneider or Rockwell PLCs with EtherNet/IP, the Model 6 may integrate more easily. Both support industry-standard protocols.
Pricing
Pricing varies by configuration, region, and distributor relationships, but general trends:
New MCC (complete lineup): Siemens and Square D are competitively priced. Differences of 5-15% either way depending on configuration and competitive pressure.
Individual Replacement Buckets:
- Siemens OEM buckets: Moderate pricing with 6-12 week lead times
- Square D OEM buckets: Moderate to higher pricing with 6-12 week lead times
- Aftermarket (MCC Depot): Competitive pricing for both brands with 3-5 day lead times
Availability and Support
Siemens
- Strong global distribution network
- Good technical support
- Parts availability is generally good for current products
- Legacy Tiastar parts can be challenging for older vintages
Square D
- Dominant distribution network in North America
- Extensive technical documentation and support
- Excellent parts availability for Model 5 and Model 6
- Schneider Electric's wide distribution makes parts accessible
Which Should You Choose?
Choose Siemens Tiastar When:
- Your facility uses Siemens PLCs and automation
- Global standardization across multiple sites is important
- IEC-style components are preferred
- You want compact bucket designs
Choose Square D Model 6 When:
- Your facility already has Square D equipment
- Parts availability and local support are priorities
- NEMA-rated components are preferred or specified
- You want the broadest aftermarket support network
For Replacement Buckets
If you already have an installed MCC, the choice is made: you need buckets compatible with your existing MCC. MCC Depot builds replacement buckets for both Siemens Tiastar and Square D Model 5 and 6 MCCs.
Call 307-442-0382 or email sales@mccdepot.com for replacement buckets compatible with either platform.