Learn about the provisions and regulations that govern the curtailment process.

From time to time, SoCalGas® may need to interrupt natural gas service to its customers. The tariff provisions governing the process of service interruption or “curtailment” are set forth in Tariff Rule 23, “Continuity of Service and Interruption of Delivery”.

(Note: While SoCalGas exercises reasonable diligence and care to furnish and deliver service to its customers, it is not liable for damages resulting from any failure to deliver natural gas or provide service, which failure results from breakage of its facilities, operating limitations or other conditions beyond its reasonable control.)

The situations requiring curtailment vary but generally fall into these categories:

  • System Curtailment
  • Localized Curtailment
  • Emergency Curtailment
  • Standby of Procurement Service Curtailment
  • Planned Maintenance Curtailment

The purpose of this overview is to help you better understand the general provisions of curtailment. It is not intended to be a substitute for Rule 23 or the other tariff schedules SoCalGas has on file with the California Public Utilities Commission (CPUC). All of these tariffs can be reviewed online.

Rule 23 will be updated on November 1, 2016. Please see the revised tariffs and proceeding (A.15-06-020) documents for complete information about the new curtailment rules and procedures.  The tariffs and proceeding information can be found at:  https://socalgas.com/regulatory/documents/a-15-06-020/D1607008_Curtailment_Procedures.pdf.

Order of Curtailment

In the event of a system curtailment, SoCalGas shall curtail service throughout its service area in the following order:

  • Interruptible noncore standby procurement service
  • Firm noncore standby procurement service
  • Unbundled as-available storage withdrawal services
  • Interruptible noncore intrastate transmission service
  • Firm noncore intrastate transmission service
  • Unbundled firm storage withdrawal services
  • Priority 2A (or “large”) core service to non-residential customers
  • Priority 1 (or “small”) core service to non-residential customers
  • Priority 1 core service to residential customers

System Curtailment

System Curtailment may occur in a large area of our service territory when the system cannot maintain adequate pressure. In such an event, curtailment of service to customers in the affected area will generally be made based on the order of curtailment shown above (and specified in Section C.1 of Tariff Rule 23). However, this order will be followed only to the extent it is operationally feasible to do so. Unbundled as-available and firm storage withdrawal service may not be available for deliveries to customers whose service is restricted as a result of a system curtailment.

Localized Curtailment

Localized curtailment occurs when a specific area of our service territory is impacted by intrastate capacity restrictions or emergencies. Curtailment of service to customers in the affected area will generally be made based on the order of curtailment shown above (and specified in Section C.1 of Tariff Rule 23). However, this order will be followed only to the extent it is operationally feasible to do so. Given the nature of the localized constraint, customers in unconstrained areas may receive service while other customers of equal or higher priority are curtailed or interrupted. Unbundled as-available and firm storage withdrawal service may not be available for deliveries to customers whose service is restricted as a result of a localized curtailment.

Emergency Curtailment

SoCalGas may need to curtail service on an emergency basis. This occurs at times where there is a threatened or actual shortage creating an emergency condition for a short duration in our ability to meet the demands of core customers. During such an emergency, we may curtail service to all or some of our customers in the most reasonable and practicable manner possible. In such an emergency, we have the right to shut off, discontinue, re-establish or continue service to such customers, irrespective of the priority or preference set forth in its tariff schedules, contracts, or rules and regulations applicable to such service.

Standby of Procurement Services Curtailment

Curtailment of Standby Procurement service gives SoCalGas the ability to institute tighter balancing requirements when system reliability is challenged due to low levels of flowing supplies. Under a Standby Procurement service curtailment, transportation customers or their balancing agents must deliver (using flowing supply or firm natural gas storage withdrawal) into the SoCalGas system at least 90% of their natural gas usage on a daily basis. Furthermore, customers may not trade daily imbalances in order to come into compliance. This is sometimes referred to as 90% daily balancing.

Planned Maintenance Curtailment

A Planned Maintenance Curtailment may occur to complete safety or maintenance work on the pipeline. Under a Planned Maintenance Curtailment, the customer is provided with advance notice through an electronic bulletin board, Envoy®, that interruptible and/or firm service will be reduced or unavailable during a specified period. SoCalGas makes every attempt to minimize customer impacts during a Planned Maintenance Curtailment.

Noncore Interruptible Service

Noncore interruptible service to affected customers will be curtailed by percentage of default rate paid, with customers paying the lowest percentage of default curtailed first. Customers paying the same percentage of default rate will be curtailed on a pro rata basis, with the exception that all affected UEG service shall be curtailed before affected cogeneration service.

Noncore Firm Service

Noncore firm service to affected customers will be curtailed by the rotation mechanism described in Section C.2 of Tariff Rule 23. For determining the order of curtailment, firm service customers shall be separated into two lists. The first list shall contain all UEG and cogeneration customers (UEG listed first) and the second list shall contain all other firm service customers. The order of customers on each list shall be established by random lottery. SoCalGas shall aggregate the listed customers into blocks of approximately 20 MMcfd, to the extent possible.

(Note: Customers with peak-day usage of 20 MMcfd or more shall remain separately listed as one curtailment block.)

The blocks to be curtailed shall be established by 1) selecting the first block from one list, 2) selecting the first block from the second list, and 3) continuing the selections down the two lists until the necessary level of curtailment is reached. Additional curtailment of firm service or (or the next firm service curtailment) will begin with the customer block immediately following the last block selected.

Curtailment Transfer Overview

SoCalGas' Rule 23 provides for firm and interruptible noncore customers to transfer intrastate curtailment requirements among themselves.

This page is for customers interested in transferring intrastate curtailment quantities under the provisions of SoCalGas ’Rule 23.
The information posted was provided by customers, including all contact information. Postings by SoCalGas are intended solely to facilitate intrastate curtailment transfers for customers of SoCalGas. No representation is made by SoCalGas as to whether or not a transfer arrangement of any curtailment quantities will, in fact, be completed.
Further, SoCalGas has no responsibility or liability regarding contacts made or arrangements completed as a result of the posting. Customers are responsible for any errors in the information provided. Postings are subject to all applicable laws and regulations.

The Curtailment Transfer Process

Customers may make arrangements to transfer or “trade” curtailment requirements. Through such an arrangement, responsibility for a specified curtailment level can be transferred from one customer (who otherwise would be required to curtail) to another customer (who would not otherwise be required to curtail).

Customers who reach mutual agreement on a transfer of curtailment requirements must execute a “Notice of Intrastate Curtailment Transfer” (Form No. 6600) (This is a sample document, not for actual use.) and submit this form to SoCalGas. The form must indicate the customer facilities involved in the trade and must specify the amount of curtailment to be transferred between each. Transfer arrangements are not valid until the required form is accepted and agreed to by SoCalGas. Accordingly, customers should submit their curtailment trades as early as possible. A copy of the transfer form may be obtained by contacting your account representative.

Noncore customers can express their interest in transferring intrastate curtailment requirements with each other and obtain each other’s contact information by adding their names to the curtailment.

Contact your account representative if you have any questions regarding transfers.

Curtailment Notice

SoCalGas shall provide notification of a curtailment to the contact personnel indicated on the Personnel Notification Form most recently submitted by the customer. Curtailment notification shall be provided by any one or more of the following means: notification posting on ENVOY, verbally by telephone or in person; in writing via email, fax or overnight postal delivery; or by text message sent via an alphanumeric pager system. SoCalGas will attempt to provide advance notice of a curtailment but only to the extent it is practical to do so. In some situations, we may need to curtail your service immediately upon notification of the curtailment. In this event, the customer shall be required to curtail or will be found in violation of curtailment.