Generac 9955 150A 1ph-120/240V Service Rated Nema 3R Automatic Transfer Switch Features:
Generac 9955 150A Service-Rated Automatic Transfer Switch
Ensures your home’s electrical system switches seamlessly to generator power. Designed as service-entrance rated equipment, it can serve as your main electrical disconnect, simplifying your installation and helping you comply with code requirements. Durable and dependable, it’s made for everyday reliability so your critical circuits stay powered when you need them most.
This switch works automatically: it detects voltage failure from the utility, transfers load to the standby generator, and then flips back once normal voltage is restored—no manual intervention required. It features open-transition switching, meaning the utility load is disconnected before generator power connects, which helps reduce stress on both the generator and your home’s wiring. All timing, sensing, and control comes from the generator’s controller, keeping the switching logic centralized and consistent.
Built tough, the 9955 is housed in a NEMA 3R rated aluminum enclosure that’s suitable for both indoor and outdoor installation. Its electrostatically applied and baked-on powder-coated finish adds corrosion resistance for long-term performance. It includes lugs sized to handle heavy gauge wiring, a heavy-duty contactor made for rugged service, and a 5-year limited warranty for peace of mind.
Whether you need standby protection for all circuits or want a service-entrance switch that integrates cleanly into your setup, the Generac 9955 offers whole-house protection with durability and smart functionality.
Key Features
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150 Amp service-rated automatic transfer switch (single-phase, 120/240V)
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Service entrance rated: functions as main disconnect where allowed
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Open-transition switching for safe switching of power sources
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Heavy-duty contactor for handling high load safely
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Enclosure: NEMA 3R aluminum suitable for indoor or outdoor weather exposure
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Powder-coated finish for corrosion resistance and long life
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Compatible with Generac standby generators using Evolution™ or Nexus™ controllers
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Supports up to 4 HVAC (24VAC) loads without additional hardware
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Optional Smart Management Modules (SMMs) allow expanded load management
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5-year limited warranty
