The Energy Code specify in §110.11 that low-voltage dry-type distribution transformers may be installed only if the manufacturer has certified model information to the Energy Commission as required by the Title 20 Appliance Efficiency Regulations. In addition, §110.1 specifies that appliances regulated by the Title 20 Appliance Efficiency Regulations may be installed only if the appliance fully complies with those efficiency regulations, and both medium-voltage dry-type and liquid-immersed transformers are included in the Appliance Efficiency Regulations.

This means that builders, electrical contractors, electrical engineers, or owners who wish to install a distribution transformer will generally need to check the Appliance Efficiency Database to confirm that the model they are selecting has been certified by the manufacturer as required by law. A link to the database is below:

https://cacertappliances.energy.ca.gov/Pages/Search/AdvancedSearch.aspx

The following types of transformers are exempt from certification requirements, and are not required to be listed in the database:

1. Autotransformers

2. Drive (isolation) transformers

3. Grounding transformers

4. Machine-tool (control) transformers

5. Nonventilated transformers

6. Rectifier transformers

7. Regulating transformers

8. Sealed transformers

9. Special-impedance transformers

10. Testing transformers

11. Transformers with tap range of 20 percent or more

12. Uninterruptible power supply transformers

13. Welding transformers.