A generator that uses an automatic or manual transfer scheme where part or all of a customer’s usage is transferred between the SCE’s distribution system and the generator, but is never in parallel with the SCE’s electric system is said to be operating in isolated mode. In isolated mode, a generator uses a “break-before-make” transfer scheme (also known as “open transition”).
You are not required to obtain an interconnection agreement with SCE in order to install or operate systems operating in isolated mode. However, the proposed transfer switch or operating scheme specifically designed and engineered for such operation must be reviewed and approved by SCE prior to operation to ensure that the generator will never operate in parallel with SCE’s electric system.
Application for Interconnection
Before you complete the design of your backup generator, you must submit a complete interconnection application package to satisfy SCE’s notice requirements for operating an isolated backup generator as per California Health and Safety Code Section 119085(b). The following documents must be completed and submitted to us:
- Rule 21 Application Form for Non-Exporting Generators (Form 14-732)
- A single line drawing
- Site/plot plan drawing
- Diagrams, manufacturer’s data, and written descriptions of the switching device or scheme proposed
No Review Fees. Generators operating under an isolated mode do not require any application fees.
For a sample on acceptable single lines and site plans, please review this: Sample drawings.
You may now apply to interconnect a backup system using our form 14-732 online!
You may also, email electronic copies of your documents (items 1 through 4, above) to Rule21@sce.com, or alternatively, mail your documents to:
Grid Interconnection & Contract Development
Southern California Edison
2244 Walnut Grove Ave
Rosemead, CA 91770 |
Interconnection Process
Following the submittal of the application package, an assigned engineer will perform a review of the technical data provided with the application. The assigned engineer will work with the customer to complete the technical review and approve the proposed configuration and operation of your emergency backup system. To demonstrate that your generator complies with Rule 21 requirements for backup operation under isolated mode, a site inspection may be necessary. Once all the technical reviews, and inspections are completed, you will receive a notification authorizing the operation of your backup system.
Additional Information
Please consult with your local permitting authority to verify any local permitting requirements. SCE does not provide permitting services.
Please visit Rule 21 page to learn more about Rule 21 and the technical requirements that may apply to your project.
SCE’s Interconnection Handbook provides information regarding technical requirements for installing and operating your generation system in a safe and reliable manner.
SCE’s Electrical Service Requirements(ESR) manual provides guidance and instructions pertaining to electrical service connections. Its purpose is to assist electrical contractors, engineers, architects, and manufacturers engaged in the installation of electrical service wiring and equipment.