APS Ten-Year Plans th BTA Presentation John Lucas Manager Transmission Planning May 22, 2008

May 22, th BTA 2 APS EHV&OUTER DIVISION115/230KV TRANSMISSION PLANS SELIGMAN ROUND VALLEY POWER PLANT 115KV&ABOVE SUBSTATION(EXISTING) 230KV&ABOVE SUBSTATION(FUTURE) LEGEND NORTH ADAMS MURAL SAN MANUEL ORACLE JUNCTION SAGUARO N.GILA PALO VERDE- HASSAYAMPA YUCCA GILA BEND REDHAWK JOJOBA GILA RIVER/ PANDA RUDD LIBERTY KYRENE SANTA ROSA WING BAGDAD YAVAPAI VERDE PINNACLE PEAK PREACHER CANYON CHOLLA TO ELDORADO TO CRYSTAL TO MEAD/ MARKETPLACE MOENKOPI NAVAJO 2011 MAZATZAL COCONINO Substation locations and line routings depict an electrical connection only and donot reflect any assumed physical locations or routing. CASA GRANDE TAT MOMOLI KNOX GAVILAN PEAK ( W A P A ) FLAGSTAFF (WAPA) TO GLEN CANYON (WAPA) SUGARLOAF 2009 EXISTING500KV LINES EXISTING345KV LINES EXISTING230KV LINES EXISTING115KV LINES PLANNED500KV LINES NUCLEAR POWER PLANT 2circuits WILLOW LAKE PLANNED230KV LINES CORONADO ( S R P ) ) FLAGSTAFF (APS WEST TS9/ RACEWAY DUGAS 2009 SUNDANCE Milligan 2009 COOLIDGE VALLEY FARMS HARQUAHALA DELANY 2010 SE TO IMPERIAL VALLEY FOUR CORNERS ( W A P A ) ( W A P A ) PINAL SOUTH 2011 DESERT BASIN TBD SUN VALLEY 2010

May 22, th BTA 3 BELL RD. I - 10 FWY. BASELINE RD.. I F W Y. I F W Y. I - 10 FWY. I F W Y. SUPERSTITION FWY. BASELINE RD.. MCDONALD RD. PINNACLE PEAK CACTUS OCOTILLO KYRENE 500kV TO JOJOBA KNOX (SRP) TO BROWNING 500kV TO SANTA ROSA REACH LONE PEAK SUNNYSLOPE MEADOWBROOK LINCOLN ST. COUNTRY CLUB ALEXANDER J/O APS/SRP To Prescott GAVILAN PEAK W A P A 2 - Circuits 345KV TO GLEN CANYON (WAPA) TO CHOLLA PHOENIX METROPOLITAN AREA TRANSMISSION PLANS Transmission Planning GLENDALE APS EXISTING 500KV LINES APS EXISTING 345KV LINES APS EXISTING 230KV LINES UNDERGROUND APS PLANNED LINES 230KV 500KV 230KV SUBSTATION (EXISTING) 230KV SUBSTATION (FUTURE) GENERATING SITE & 230KV SUBSTATION JOINT OWNSHIP OTHER COMPANY LINES J/O CAREFREE HWY. BETHANY HOME RD. Substations locations and line routings are approximate 345KV TBD SURPRISE AGUA FRIA EL SOL DEER VALLEY RUDD TO PALO VERDE WEST PHOENIX WESTWING LIBERTY/TS4 BUCKEYE TO GILA BEND To Navajo W A P A TO PALO VERDE 500KV To New Waddell W A P A WHITE TANKS (APS) TO PALO VERDE 500kv J/O L I T C H F I E L D R D Raceway/TS9 P I M A R D TS TBD TS1/Trilby Wash 2010 Sun Valley 2010 TBD 2010 TS J/O SRP PALM VALLEY TBD AVERY JOJOBA 2013

May 22, th BTA 4 Changes from 2006 to 2008 ProjectStatus Palm Valley 230/69KV SubstationCompleted Rudd-Palm Valley-TS4 230KVCompleted Flagstaff 345/69kV interconnectionChanged to I/S date of 2010 Jojoba cut-in of TS4-Panda 230kVChanged to I/S date of 2013 PV Hub-Sun Valley(TS5) 500kVChanged to I/S date of 2010

May 22, th BTA 5 Changes from 2006 to 2008 ProjectStatus Sun Valley(TS5)- Trilby Wash(TS1) 230kV Changed to I/S date of 2010 Trilby Wash(TS1)-TS2-Palm Valley 230kV w/TS2 I/S OF 2011 Changed to I/S date of 2010 w/TS2 I/S date of 2011 Pinnacle Peak-TS6-Avery-Raceway-TS9 230kV Changed to I/S date of 2010 Milligan 230/69 kV SubstationNew Project

May 22, th BTA 6 Sundance-Pinal South 230 kVNew Project Desert Basin-Pinal South 230 kVNew Project SE10 230/69 kV SubNew Project N.Gila-Yucca 230 kV New Project - TBD Sun Valley – TS9 230kV lineNew Project - TBD SunValley-TS11-Buckeye 230 kV New Project - TBD SunValley-TS10-TS kV New Project - TBD Changes from 2006 to 2008

May 22, th BTA 7  All projects with in service dates have had technical studies and are included in the 10 Year Plan that has been filed: Thermal and Post-Transient analysis (all 10 years) Transient Stability analysis (2011 & 2016) RMR Studies SWAT studies (N-1-1 and Extreme Contingency)  All transmission projects with an in-service date listed as To Be Determined have not had power flow studies performed Technical Studies and Stakeholders

May 22, th BTA 8 Technical Studies and Stakeholders  All projects are included in common, jointly built base cases  Plans are presented to SWAT and WestConnect Participation in projects are open to all stakeholders Project updates are regularly given at SWAT and WestConnect meetings  WECC Transmission projects seeking a WECC rating go through the WECC 3-phase rating process

May 22, th BTA 9 Technical Studies and Stakeholders  APS holds regular coordination meetings with SRP and WAPA  Project(s) interconnecting into jointly owned facilities undergo interconnection process and review by appropriate technical review group; i.e. WATS  Plans included in all WECC, WestConnect, and SWAT base cases

May 22, th BTA 10