Generac RTSW400A3 400A Service-Entrance Automatic Transfer Switch (NEMA 3R)
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At a glance
- Amperage
- 400A
- Voltage/Phase
- 120/240V single-phase
- Service Entrance Rated
- Yes
- Enclosure
- NEMA 3R aluminum (indoor/outdoor)
- Transition Type
- Open transition (automatic)
- Withstand Rating
- 22,000A
- Listings
- ETL listed; ETL-recognized contactor
- Load Management
- Integrated Smart A/C Module — manages up to 4 HVAC loads (expandable with Smart Management Modules)
- Lug Range
- 600 MCM - #4 or (2) 1/0 - 250 MCM
- Dimensions
- 42.9" H x 16.7" W x 10.0" D
- Weight
- 140 lbs
- Warranty
- 5-year limited
Not sure if this fits?
Why this generator
- 400A service entrance rated Smart Switch — doubles as your main service disconnect, eliminating a separate disconnect panel
- Rugged aluminum NEMA 3R enclosure with baked powder-coat finish stands up to rain, snow, and ice for indoor or outdoor installation
- Built-in Smart A/C Module manages up to four HVAC loads with zero extra hardware, so a smaller generator can power a bigger home
- Heavy-duty ETL-recognized Generac contactor with a 22,000A withstand rating, built for years of dependable transfers
- Seamless pairing with Generac air-cooled and liquid-cooled home standby generators using Evolution or Nexus controllers
- Backed by Generac's 5-year limited warranty
Everything you need to know
Generac RTSW400A3 400a service-entrance automatic transfer switch (NEMA 3R enclosure). 120/240V single-phase, designed to pair with Generac air-cooled home standby generators.
Genuine Generac unit from a factory-authorized dealer. Ships via calculated freight — shipping shown at checkout (heavy/hazmat item). Professional installation available in NC & SC.
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. Most items leave the warehouse in 2–4 business days.
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.