Generac 9951 200A 1ph-120/240V Service Rated Nema 3R Automatic Transfer Switch with Integrated SPD Features:
Generac 9951 200A Automatic Transfer Switch Features:
The Generac 9951 200A Automatic Transfer Switch is built to be the backbone of your standby power system, offering full-house protection with high capacity and code class performance. Rated at 200 amps and service-rated, it can function as your main electrical disconnect in many installations. What sets it apart is the built-in Surge Protection Device (SPD), which guards your home's electronics, appliances, and circuitry from harmful voltage surges and transient spikes—no separate surge protector needed.
When utility power drops or fails, the 9951 senses the event and immediately transfers the power load to the standby generator. Once utility service returns to acceptable levels, it switches back automatically. The open-transition design ensures that utility and generator power are never connected at the same time, helping protect both equipments and wiring. All control logic and safety timing are integrated, providing smooth, reliable operations without manual switching.
Encased in a service-rated aluminum enclosure with a NEMA 3R rating, this switch is suitable for both outdoors and sheltered indoor installations. The aluminum housing is corrosion resistant and rugged, built to withstand weather and environmental exposure over time. The internal components—heavy-duty contactor, properly sized lugs, etc.—are designed for durability and frequent switching under high electrical load. The switch also includes ambient wiring and clear access to make installation more straightforward.
Because it’s designed for compatibility with Generac standby generators, going with the 9951 means easier control integration, consistent reliability, and less need for add-ons. It's an investment in both backup power and protection—power transfer, surge defense, and high amp service entrance rating all in one unit.
Key Features
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200 Amp service-rated automatic transfer switch (single-phase, 120/240V)
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Integrated Surge Protection Device (SPD) for whole-home surge defense
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Service entrance rated—functions as the main disconnect where permitted by electrical code
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Open-transition power switching: prevents overlap between utility and generator power
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NEMA 3R rated aluminum enclosure for outdoor or indoor installation
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Heavy-duty internal contactor and large lug terminals for high-capacity load handling
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Compatible with Generac standby generator controller systems for smooth integration
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Weather-resistant finish for lasting performance in diverse environments
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Designed for frequent switching without performance degradation
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Comes with manufacturer’s warranty for peace of mind
