Model Number: 71257
Simplify standby-generator installations for homes with split 400 Amp electrical service using the Briggs & Stratton 71257 Dual 200A / Split 400A Symphony® II SED Power Management Automatic Transfer Switch.
Designed specifically for residential electrical systems where a 400 Amp utility service is divided between two 200 Amp distribution panels, the 71257 combines the functionality of two coordinated 200 Amp transfer switches into a single enclosure.
Instead of installing two separate 200 Amp automatic transfer switches, the Briggs & Stratton 71257 provides a more integrated solution for compatible split-400A applications. Its service-entrance-rated design, NEMA 3R enclosure, 120/240V single-phase configuration, UL 1008 listing, and Symphony II power-management capability make it an important component for larger residential standby-power systems.
Key Features
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Designed for Split 400 Amp Service: Built specifically for homes where 400 Amp utility service is divided between two 200 Amp main distribution panels.
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Dual 200 Amp Transfer Capability: Incorporates the functionality of two coordinated 200 Amp automatic transfer switches into one enclosure.
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2-in-1 Transfer Switch Design: Eliminates the need for two separate 200 Amp transfer-switch enclosures in compatible split-400A applications.
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Automatic Utility Monitoring: Detects loss of utility power and signals the compatible Briggs & Stratton standby generator to start.
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Automatic Power Transfer: Transfers the applicable electrical loads to generator power once backup power is available.
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Automatic Return to Utility: Transfers the electrical system back to utility power when normal service has been restored.
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Service Entrance Rated: Includes service-entrance disconnect capability for compatible dual-200A residential services.
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Symphony® II Power Management: Supports power management for controlling and prioritizing electrical loads according to available generator capacity.
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120/240V Single Phase: Designed for compatible residential 120/240V, 60 Hz single-phase electrical systems.
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2-Pole Configuration: Designed for the specified single-phase split-service application.
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NEMA 3R Enclosure: Suitable for applicable indoor or outdoor installations requiring a NEMA 3R enclosure.
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UL 1008 Listed: Listed to UL 1008 requirements for transfer-switch equipment.
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Smaller Installation Footprint: Combines two transfer functions into one enclosure, helping simplify compatible installations.
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Designed for Briggs & Stratton Standby Systems: Intended to be bundled with a compatible Briggs & Stratton standby generator.
What Is a Split 400 Amp Electrical Service?
Some larger homes have 400 Amp electrical service to accommodate higher overall electrical demand.
Instead of feeding the entire 400 Amp service through a single distribution panel, a split-400A configuration divides the incoming utility service between two 200 Amp electrical panels.
A simplified configuration looks like this:
400A Utility Service → 200A Main Panel + 200A Main Panel
A conventional standby-generator installation could require a separate 200 Amp transfer switch for each panel.
The Briggs & Stratton 71257 addresses this configuration by incorporating both transfer functions into a single enclosure.
Dual 200A Transfer Switches in One Enclosure
The primary advantage of the Briggs & Stratton 71257 is its 2-in-1 design.
Rather than installing two individual 200 Amp automatic transfer switches, the 71257 combines a coordinated pair of transfer switches into one enclosure.
This can provide several advantages for compatible installations:
- Fewer separate transfer-switch enclosures
- More compact equipment arrangement
- Simplified split-400A standby-system design
- Coordinated operation across both 200 Amp panels
- Cleaner installation for larger residential electrical systems
The exact installation configuration should be determined by a qualified electrical professional according to the property's service arrangement.
How the Briggs & Stratton 71257 Works
During normal operation, the home's two 200 Amp distribution panels receive electricity from the utility service.
If utility power is interrupted, the 71257 automatic transfer system detects the outage and signals the compatible Briggs & Stratton standby generator to start.
Once generator power is available, the transfer switch manages the transition of the applicable electrical system from utility power to generator power.
When normal utility service returns, the process is reversed and the electrical loads are transferred back to utility power.
This automatic operation allows a properly configured standby-power system to respond to an outage without requiring the homeowner to manually switch between power sources.
Symphony II Power Management
One of the most important features of the Briggs & Stratton 71257 is its Symphony® II Power Management capability.
A home with 400 Amp electrical service can potentially have far more connected electrical demand than a residential standby generator can supply simultaneously.
Power management helps address this difference.
Instead of attempting to operate every large electrical load at the same time, a properly configured Symphony II system can manage selected loads according to available generator capacity and system priorities.
This can be particularly useful for homes containing equipment such as:
- Multiple HVAC systems
- Electric water heaters
- Well or sump pumps
- Pool and spa equipment
- Electric ranges
- Clothes dryers
- Additional high-demand household equipment
The actual power-management configuration depends on the generator, connected equipment, and installation requirements.
Important: Split 400A Does Not Mean 400 Amps of Generator Output
The 400 Amp designation describes the home's utility-service configuration and transfer-switch application. It does not mean the standby generator supplies 400 amps of backup power.
Likewise, combining two 200 Amp transfer functions does not increase generator output.
The connected Briggs & Stratton generator remains limited to its rated electrical capacity.
For example, a properly configured standby system may provide generator access across both 200 Amp panels, but the combined electrical demand placed on the generator must remain within available generator capacity.
This is why power management can be particularly important in larger homes with 400 Amp electrical service.
Service Entrance Rated
The Briggs & Stratton 71257 is service-entrance rated with disconnect capability for compatible dual-200A residential electrical-service configurations.
This allows the transfer equipment to perform an important role within the home's service and standby-power architecture while reducing the need for separate transfer-switch equipment in compatible installations.
The actual service-entrance configuration must be determined according to the home's electrical system and applicable electrical codes.
NEMA 3R Indoor/Outdoor Enclosure
The transfer switch is housed in a NEMA 3R enclosure, making it suitable for applicable indoor and outdoor installations.
This provides greater flexibility when determining equipment placement during the design of a standby-generator system.
Final placement should comply with Briggs & Stratton installation requirements and applicable electrical and building codes.
Specifications
| Specification |
Details |
| Brand |
Briggs & Stratton |
| Model Number |
71257 |
| Product Type |
Automatic Power Management Transfer Switch |
| Application |
Split 400 Amp Residential Service |
| Transfer Configuration |
Dual 200 Amp |
| Service Entrance Rated |
Yes |
| Poles |
2 |
| Frequency |
60 Hz |
| Phase |
Single Phase |
| Voltage |
120/240V |
| Power Management |
Symphony II |
| Enclosure |
NEMA 3R |
| Indoor / Outdoor |
Yes |
| Certification |
UL 1008 |
| Generator Compatibility |
Compatible Briggs & Stratton Standby Generator Systems |
Who Should Consider the Briggs & Stratton 71257?
The 71257 is specifically intended for compatible homes with split 400 Amp electrical service.
It may be appropriate when the property has:
- 400 Amp residential electrical service
- Two 200 Amp main distribution panels
- A compatible Briggs & Stratton standby generator
- Large electrical loads distributed between both panels
- A need for automatic standby-power transfer
- A need for Symphony II load management
For a conventional home with a single 200 Amp electrical service, a standard 200 Amp transfer switch may be more appropriate.
Frequently Asked Questions
What is the Briggs & Stratton 71257?
The Briggs & Stratton 71257 is a Dual 200 Amp / Split 400 Amp automatic transfer switch with service-entrance disconnect and Symphony II power management.
It is designed for compatible homes where a 400 Amp utility service is divided between two 200 Amp electrical panels.
Why use one 71257 instead of two 200 Amp transfer switches?
The 71257 combines the functionality of two coordinated 200 Amp transfer switches into a single enclosure.
For compatible split-400A installations, this can reduce the number of separate transfer-switch enclosures and provide a more integrated standby-power configuration.
Does the 71257 provide 400 amps of generator power?
No.
The 400 Amp designation refers to the electrical-service configuration the transfer switch is designed to accommodate.
Actual backup-power capacity is determined by the connected standby generator.
Can it provide generator power to both 200 Amp panels?
The 71257 is designed for split-400A applications involving two 200 Amp distribution panels.
The amount of equipment that can operate simultaneously remains limited by the connected generator's available capacity and the system's power-management configuration.
Does the 71257 include power management?
Yes. The supplied product information identifies the 71257 as a Symphony II SED Power Management Transfer Switch.
Power management can help coordinate selected electrical loads so the standby generator is not required to operate every high-demand load simultaneously.
Is the Briggs & Stratton 71257 service entrance rated?
Yes. The supplied specifications identify the 71257 as service-entrance rated with disconnect capability for dual 200 Amp home services.
Can the transfer switch be installed outdoors?
The 71257 uses a NEMA 3R enclosure designed for applicable indoor and outdoor installations.
What generator works with the Briggs & Stratton 71257?
The supplied product information states that the transfer switch must be bundled with a Briggs & Stratton standby generator.
The specific generator and transfer-switch combination should be verified for compatibility before installation.
Shop Briggs & Stratton Transfer Switches at AC Units For Less
For homes with split 400 Amp electrical service, the Briggs & Stratton 71257 Dual 200A / Split 400A Symphony II SED Power Management Transfer Switch provides a streamlined alternative to installing two separate 200 Amp transfer-switch enclosures.
Its combination of dual 200 Amp transfer capability, service-entrance disconnects, Symphony II power management, 120/240V single-phase operation, NEMA 3R construction, and UL 1008 listing makes it an important component for compatible high-capacity residential standby-power systems.
Shop Briggs & Stratton standby generators, automatic transfer switches, power-management equipment, and generator accessories at AC Units For Less.
Important: The 71257 does not provide 400 amps of generator output. Generator capacity, service configuration, transfer-switch compatibility, load management, and installation requirements should be evaluated by a qualified electrical professional according to Briggs & Stratton instructions and applicable electrical codes.