Generac 9979 400A Service-Entrance Automatic Transfer Switch with Surge Protection (NEMA 3R)
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At a glance
- Brand
- Generac
- Shipping
- Low cost ground shipping — calculated at checkout
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Everything you need to know
This 400-amp automatic transfer switch monitors utility power and automatically transfers your home or building to generator power during an outage, then switches back once utility power returns. It is service-entrance rated, so it can be installed as the main service disconnect.
Specifications
- Amperage: 400A
- Service-entrance rated: Yes
- Voltage: 120/240V single-phase
- Enclosure: NEMA 3R for outdoor or indoor installation
- Surge protection: Integrated whole-home surge protective device
- Smart transfer switch with integrated service disconnect
- Smart load management: Compatible with Generac smart management modules (sold separately)
- Transfer: Automatic, with utility power sensing and return-to-utility switching
Professional installation by a licensed electrician is required. Installation service is available in North and South Carolina.
Frequently asked questions
Is this a genuine OEM part?+
Yes — sold and shipped as a genuine Generac part from a factory-authorized dealer.
Will it fit my unit?+
Check your model and year — message us with that info and we'll confirm fit before you order.
How fast does it ship?+
Low cost ground shipping — calculated at checkout (batteries, transfer switches and oversized items). Most leave the warehouse in 2–4 business days.
What's the return policy?+
30-day returns on unused parts and accessories in original packaging.
Fast nationwide shipping
Low cost ground shipping — calculated at checkout. Typically ships in less than 2 weeks.
Install help, no upsell
We size, spec, and connect you with a vetted local installer — or talk your contractor through it for free.
Genuine Generac part
Sold and shipped as a genuine Generac OEM part from a factory-authorized dealer. 30-day returns on unused parts in original packaging.