Electrical Code Compliance for ATS Installation — What Should I Know?

ATS Sizing and Installation Requirements

When sizing an automatic transfer switch (ATS), you should refer to the NEC and the manufacturer’s instructions. The NEC requires an ATS to be sized for the maximum load of the connected equipment, including motors, lighting, and appliances. For example, a 200-amp ATS may be required for a 200-amp service, while a 400-amp ATS may be required for a 400-amp service. Additionally, the ATS should be installed in a location that is accessible and allows for easy maintenance.

Electrical Safety Codes and Grounding Requirements

Electrical safety codes, including grounding and bonding requirements, are critical for ATS installation. The NEC requires that the ATS be bonded to the grounding system, which includes the grounding electrode system, the neutral conductor, and the grounding conductor. The ATS should also be installed with an approved ground fault circuit interrupter (GFCI) to prevent electrical shock. The NEC requires that the ATS be installed in a location that is protected from the elements and is easily accessible for maintenance.

Testing and Inspection Requirements

Proper testing and inspection of the ATS are essential to ensure safe and efficient operation. The NEC requires that the ATS be tested before installation and after any maintenance or repairs. Testing should include verifying the ATS’s ability to transfer loads between the generator and the grid, as well as its ability to detect and respond to grid outages. Additionally, the ATS should be inspected regularly to ensure that it is properly installed, sized, and maintained.