NOTICE DATE: March 20, 2009

NOTICE TYPE: W-A031309-02 Operations

SHORT DESCRIPTION: Conditional North to Houston CREs

INTENDED AUDIENCE: ERCOT Market Participants

DAY AFFECTED: Duration of double circuit outage affecting N-H CSC

LONG DESCRIPTION: ERCOT is updating the North to Houston CRE real-time posting to reflect the addition of the Peters to Flewellen 138kV line and the Tomball to Hockley 138kV line as CREs that will be used for the duration of the Singleton substation project when double circuits feeding into the Houston area from the North are unavailable. These additional CREs were requested to assist ERCOT in setting North to Houston CSC thermal limits during the Singleton substation cut in. The anticipated date to begin using the conditional CREs is March 23, 2009; at which time these CREs may be utilized in Day-Ahead studies and Real-Time Operations. The CSC/CRE website located at the link below will be updated to include these additional CREs.

http://mospublic.ercot.com/ercot/jsp/csc_cre.jsp

In the event that Zonal Management Techniques fail to control congestion, ERCOT will also use Local Congestion Management Techniques and notify the market via the ERCOT MIS Operations Message page.

http://oldercot.ercot.com/ercotPublicWeb/Message/MessageSearch.asp

When the Singleton project is complete, these CREs will be removed from the CSC/CRE website, and their use in the Day-Ahead and Real-Time Operations will be suspended. ERCOT will send a market notice to confirm the CREs are no longer in effect at the conclusion of the Singleton project.

CONTACT: If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via e-mail at [log in to unmask].

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