1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Weekly Update July 02, 2010

2. http://nodal.ercot.com 2 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. http://nodal.ercot.com 3 Agenda Anti-trust Admonition Environment Report –Planned / unplanned outages –CIM Load –Known Issues Standing Reports and Updates –General reminders / updates Question and Answers / General Discussion ERCOT asks that Market Participants log into the WebEx session using their company name and then their name. This will allow ERCOT to take roll-call offline

4. Market Trials 2010 Roadmap http://nodal.ercot.com 4

5. http://nodal.ercot.com 5 Day-to-day operations summary: Planned / Unplanned Outages of EDS / CIM Load Planned Outages –07/02/2010 6:00 P.M. – 11:00 P.M. Database maintenance activities are planned during this period and will affect availability of following application services: –EWS ( Web Services) –OS UI Unplanned Outages –06/29/2010 12:10 P.M. – 12:45 P.M. Users were unable to launch OS UI via the MIS portal due to an application script failure. Target CIM Load dates for the month of June / July –7/01/2010 – Complete – reminder 2 week load schedule starts –7/14/2010

6. http://nodal.ercot.com 6 General reminders / updates ERCOT has developed a user guide along with a web-based user interface training module to introduce the user interface and provide ongoing reference material for end users of the application. The introductory sessions are targeted at personnel from TSPs, QSEs and Resource Entities and are intended to: –Review ERCOT market rules related to outage coordination –Describe roles and responsibilities for ERCOT and market participants –Introduce the use and design of the Outage Scheduler –Demonstrate the basic functions of the Outage Scheduler –Describe the interfaces between the outage scheduler and other Nodal Market applications. TSPs and QSEs are encouraged to send personnel that will either submit or maintain outage information on the Outage Scheduler as well as those that may need to generate reports on outages. The location and schedules of the remaining courses are shown below: Date Time City Address 15-Jul-1009:00 to 15:00 Houston, TX CenterPoint Energy Energy Control and Data Center 16303 Tomball Parkway Houston, TX 77065

7. http://nodal.ercot.com 7 General reminders / updates Reminder: ERCOT will be opening a window of optional Outage Scheduling testing –Testing opened on 7/1/2010 and close on 7/9/2010 –During this period Outages will be de-coupled from the DAM to allow MPs flexibility to test varying scenarios –MPs should contact ERCOT in advance to coordinate approvals or other scenarios

8. http://nodal.ercot.com 8 Environment Report: Known Issues Known issues posted to the readiness center at: http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html New Known Issues: Closed Known Issues: Open OS UI - Warnings that do not require an action by the user are not being removed from the warnings table Warnings that come in for an Opportunity Outage that do not require an action by the user are not being removed by the system.ERCOT is looking into this issue. Closed Load Resources are missing from the Equipment list

9. http://nodal.ercot.com 9 Q&A Q&A / Open Forum