Choosing the Right Transfer Switch Size
Transfer switch sizing is straightforward when you understand the key factors. The transfer switch must accommodate your home’s full electrical service amperage to ensure safe and code-compliant operation.
Match Your Panel Amperage
The most important factor is matching the transfer switch to your main electrical panel’s amperage rating. Look at the main breaker in your panel to find your service amperage. Common residential sizes include 100A, 150A, and 200A. Select a transfer switch rated for that amperage or higher. Installing a transfer switch rated below your panel amperage is a code violation.
Generator Compatibility
Most generator manufacturers recommend or require specific transfer switch models to work with their generators. Generac generators pair with Generac transfer switches, Kohler with Kohler switches, and so on. While third-party universal switches exist, using the manufacturer-matched switch ensures full warranty coverage and proper communication between the generator and switch electronics.
Whole-House vs. Load-Managed
If your generator is large enough to power your entire panel, a whole-house transfer switch is the simplest option. If your generator is smaller than your total load, a load-managed transfer switch intelligently cycles circuits to stay within the generator’s capacity. Load management can allow a 16kW to 22kW generator to effectively serve a home that would otherwise require a 24kW or larger unit.
Service Entrance Rated vs. Non-Service Entrance
If the transfer switch will be installed between the utility meter and the main panel (ahead of the main breaker), it must be service entrance rated. If installed downstream of the main breaker, a standard ATS is acceptable. Your electrician will determine the correct configuration during the site evaluation.
Need help matching a transfer switch to your generator? Call IB Lighting at (800) 674-9019 and we will confirm compatibility before you order.