Energy Resources Department
Business Objective: Electric


Mission Statement
Provide safe, reliable and efficient electric power to Mesa customers.
Desired Outcomes
  • Electric energy is acquired for and transmitted to Mesa's electric distribution system reliably at the lowest possible costs.
  • Electric energy is distributed safely and reliably to our customers.
  • Our customers' electric energy consumption is accurately and safely measured.
                                                                                                                               Energy Resources Performance Dashboard

Providing Safe, Reliable and Efficient Electric Service for over 100 Years!

The City of Mesa has been offering safe, reliable, and efficient electric utility service for over 100 years. In 1917, the City of Mesa acquired the electric utility that now provides residential and commercial electric utility service to over 17,000 customers within its 5.5 mile radius service area. The City of Mesa Electric Service Area includes the city-center (downtown) and surrounding areas.  
Performance Measures
Electric O&M Cost/Customer
O&M Cost/Customer is a good indicator of whether the costs of our electric staff and operations are growing proportionally in comparison to the growth of the electric system as measured by the change in customers.
Energy Resources uses O&M Cost/Customer as a measure of Performance Improvement by comparing actual O&M Cost/Customer in the current year to the budgeted O&M dollars from the prior year divided by the forecasted customer count (our target values). The data also allows a comparison of how actual O&M Cost/Customer changes from year to year and allows us to measure whether our costs are increasing in proportion to the growth in the number of customers we serve.
Thus, O&M Cost/Customer is a measure of “technical” efficiency where O&M Costs would be the “input” and Customers, when served safely and reliably, would be the measure of output. Efficiency measures how well a business converts inputs such as capital, labor & materials into outputs such as revenue, products and services.

The January 2023 O&M Cost/Customer was $118.32/Customer
  • 8% below monthly target of $128.74/Customer.
    • January O&M costs were $2,423 more than the forecast used to develop the target.
Actuals are above the monthly target due to TBD.

The December 2022 O&M Cost/Customer was $97.48/Customer
  • 10% below monthly target of $108.29/Customer.
    • December O&M costs were $17,786 more than the forecast used to develop the target.
Actuals are above the monthly target due to TBD.

The November 2022 O&M Cost/Customer was $79.04/Customer
  • 13% below monthly target of $91.04/Customer.
    • November O&M costs were $68,818 less than the forecast used to develop the target.
Actuals are below target due to TBD.

The October 2022 O&M Cost/Customer was $65.63 /Customer
  • 11% below monthly target of $73.84/Customer.
    • October O&M costs were $27,233 less than the forecast used to develop the target.
Actuals are below target due to TBD.

The September 2022 O&M Cost/Customer was $49.83/Customer
  • 12% below monthly target of $56.65/Customer.
    • September O&M costs were $43,282 less than the forecast used to develop the target.
Actuals are below target due to TBD.

The August 2022 O&M Cost/Customer was $29.04./Customer
  • 14% below monthly target of $33.91/Customer.
    • August O&M costs were $19,541 less than the forecast used to develop the target.
Actuals are below target due to TBD.

The July 2022 O&M Cost/Customer was $12.85/Customer
  • 24% below monthly target of $16.97/Customer.
    • July O&M costs were $78,761 less than the forecast used to develop the target.
Actuals are below target due to emergency line services invoice processing also underspending in material purchases and professional services for items such as SRP billings and tree trimming.



Electric Reliability - Outage Duration (SAIDI)

The February 2023 Reliability Duration Index: Target = 0.2 minutes
  • Actual SAIDI was 0.265 minutes of interruptions per customer.
  • 30% above the monthly target of 0.2.
  • No major events in February
  • 79 customers were affected during the month.
The cause of the outages was attributed to Tree related events 100%.
  • 2-22-23 – 650 E. 1st St, Circuit 234, 25 customers for 31 minutes Palm Frond TREE
  • 2-22-23 – 463 N. Macdonald, Circuit 194, 6 customers for 41 minutes Cypress fall TREE
  • 2-26-23 – 57 N. Hunt Dr. E, Circuit 231, 48 customers for 75 minutes Palm Frond TREE

The January 2023 Reliability Duration Index: Target = 0.19 minutes
  • Actual SAIDI was 0.10 minutes of interruptions per customer.
  • 47% below the monthly target of 0.19.
  • 2 non-major event that caused 2 outages.
  • 19 customers were affected during the month.
The cause of the outages was attributed to Equipment Failure 50% and Human Error (SETTINGS) 50%.
  • 1-19-23 – 505 W. 8th Ave, Circuit 171, 15 customers for 109 minutes PM XFMR CHANGEOUT
  • 1-26-23 – 250 E. 1st Ave, Circuit 211, 4 customers for 29 minutes VI SETTINGS UPDATED

The December 2022 Reliability Duration Index: Target = 0.46 minutes
  • Actual SAIDI was .126 minutes of interruptions per customer.
  • 73% below the monthly target of 0.46.
  • 2 non-major event that caused 2 outages.
  • 47 customers were affected during the month.
The cause of the outages was attributed to Tree 50% and Bird 50%. 
  • 12-12-22 – 538 W. Clark, Circuit 243, 32 customers for 37 minutes BLOWN LINE FUSE PALM FROND
  • 12-17-22 – 727 W. 1st Place, Circuit 183, 15 customers for 56 minutes BLOWN XFMR FUSE BIRD

The November 2022 Reliability Duration Index: Target = 3.13 minutes
  • Actual SAIDI was .021 minutes of interruptions per customer.
  • 93% below the monthly target of 3.13.
  • 1 non-major event that caused 2 outages.
  • 13 customers were affected during the month.
The cause of the outages was attributed to Bird 100%. 
  • 11-21-22 – 428 W. 1st St, Circuit 243, 5 customers for 41 minutes BLOWN LINE FUSE BIRD
  • 11-21-22 – 141 N. Date, Circuit 243, 8 customers for 21 minutes BLOWN LINE FUSE BIRD

The October 2022 Reliability Duration Index: Target = 0.97 minutes
  • Actual SAIDI was 1.39 minutes of interruptions per customer.
  • 43% above the monthly target of 0.97.
  • 4 non-major events that caused 5 outages.
  • 838 customers were affected during the month.                                                                                                                                                                                                            
The cause of the outages was attributed to Tree related 40%, Weather 40,% and Human Error 20%. 
  • 10-3-22 – 120 N. Stapley Dr, Circuit 231, 1 customer for 75 minutes TREE
  • 10-15-22 – 522 W. 3rd St, Circuit 243, 24 customers for 50 minutes STORM
  • 10-15-22 – 142 N. Date, Circuit 183, 32 customers for 108 minutes STORM/TREE
  • 10-15-22 – 612 W. 1st St, Circuit 183, 7 customers for 121 minutes STORM
  • 10-27-22 –Kellwood Substation, Circuit 183, 774 customers for 24 minutes HUMAN SWITCHING ERROR
There were also two (2) Major Events during the month of October that caused two (2) separate outages. A late monsoon storm combined with heavy rain and lightning caused an equipment failure that triggered the circuit breaker to lock out, creating a circuit outage on October 16th. On October 26th, a pad-mounted get-a-way switch faulted internally causing a circuit outage. Switching was performed to isolate the failed switch and restore power. Later that week the switch was replaced, and the circuit was switched back to its normal condition. The October SAIDI including major events was 17.3 minutes.

The September 2022 Reliability Duration Index: Target = 1.13 minutes
  • Actual SAIDI was 0.021 minutes of interruptions per customer.
  • 81% below the monthly target of 1.13.
  • 1 non-major event that caused 1 outage.
  • 17 customers affected.
The cause of the outage was Overhead Equipment Failure.
•   9-6-22 – 712 W. 1st Place, Circuit 183, 17 customers for 22 minutes TRANSFORMER FUSE/OVERLOAD
There was one (1) event that caused one (1) outage during the month of September. The reportable outage disrupted power to 17 customers and resulted in a “total” SAIFI (frequency) index of 0.001 interruption per customer which was below the target of 0.010 for the month of September. There were no Major Events during the month of September.

The August 2022 Reliability Duration Index: Target = 1.03 minutes
  • Actual SAIDI was 0.411 minutes of interruptions per customer.
  • 60% below the monthly target of 1.03.
  • 5 non-major events that caused 5 outages.
  • Average customers affected per outage were 20.
Causes for the five (5) outages were attributed to Trees 40%, Overhead Equipment Failure 20%, Bird 20%, and Vehicle Accident 20%.
  • 8-4-22 – 650 E. 1st St. Circuit 161, 44 customers for 169 minutes TRANSFORMER FUSE/WEATHER
  • 8-9-22 – 233 N. Fraser Dr. Circuit 222, 42 customers for 93 minutes TRANSFORMER FUSE/PALM FROND
  • 8-9-22 – 531 E. University, Circuit 234, 3 customers for 43 minutes TRANSFORMER FUSE/DEFECTIVE
  • 8-16-22 – 715 S. Mesa Dr. Circuit 232, 1 customer for 103 minutes TRANSFORMER REPLACE/CAR HIT
  •  8-29-22 – 867 S. Coleman Circuit 242, 12 customers for 91 minutes TRANSFORMER FUSE/BIRD
There was also one (1) Major Event during the month of August that caused three (3) separate outages. On Saturday, August 6th at approximately 7 AM, a contractor working at 215 S. Robson was operating an excavator that snagged a Cox cable TV high tension line. The line broke causing several poles to shock load, breaking a cross arm, and causing two (2) 4/0 copper powerlines to fall. Wires slapped into several streetlight heads causing them to burn up internally. Secondary neutrals and ground wires were damaged at numerous locations. The August SAIDI including major events was 1.713 minutes.

The July 2022 Reliability Duration Index: Target = 2.91 minutes
  • Actual SAIDI was 0.821 minutes of interruptions per customer.
  • 72% below the monthly target of 2.91.
  • 3 non-major events that caused 3 outages.
  • Average customers affected per outage were 40.
Causes for the three (3) outages were attributed to Equipment Failures/Overloads 66% and Mylar balloons 33%.
  • 7-11-22 – 151 E. 1st Ave Circuit 161, 34 customers for 169 minutes TRANSFORMER FAILURE
  • 7-12-22 – 844 N. Grand Circuit 181, 17 customers for 114 minutes TRANSFORMER OVERLOAD
  • 7-23-22 – 326 E. 7th Dr. Circuit 174, 68 customers for 96 minutes MYLAR BALLOONS
There was one (1) Major Event during the month of July that caused 12 separate outages. Sunday evening on July 17, a monsoon storm combined with high winds and lightning caused several power outages in the Mesa electric service area and beyond. COM crews worked throughout the night on into the next day, making repairs and restoring power to the affected customers. Emergency response contract crews also assisted with the repairs the following day. The July SAIDI including major events was 24.83 minutes.


Average Residential Electric Bill Compared to SRP
Mesa Average Residential Customer Electric bills are 4.8% less than SRP for the period October 2020 to September 2021.
Electric Reliability Outage Frequency (SAIFI)

February 2023 Reliability Frequency Index: Target = 0.003 Interruptions per Customer
There were no major events during the month of February. The reportable outages disrupted power to 79 customers and resulted in a “total” SAIFI (frequency) index of 0.004 interruption per customer which was above the target of 0.003 for February. There were no Major Events during the month of February.

January 2023 Reliability Frequency Index: Target = 0.003 Interruptions per Customer
There were two (2) events that caused two (2) outages during the month of January. The reportable outages disrupted power to 19 customers and resulted in a “total” SAIFI (frequency) index of 0.001 interruption per customer which was below the target of 0.003 for January. There were no Major Events during the month of January.

December 2022 Reliability Frequency Index: Target = 0.009 Interruptions per Customer
There were two (2) events that caused two (2) outages during the month of December. The reportable outages disrupted power to 47 customers and resulted in a “total” SAIFI (frequency) index of 0.003 interruption per customer which was below the target of 0.009 for December. There were no Major Events during the month of December.

November 2022 Reliability Frequency Index: Target = 0.019 Interruptions per Customer
There was one (1) event that caused two (2) outages during the month of November. The reportable outages disrupted power to 13 customers and resulted in a “total” SAIFI (frequency) index of 0.001 interruption per customer which was below the target of 0.019 for November. There were no Major Events during the month of November.

October 2022 Reliability Frequency Index: Target = 0.005 Interruptions per Customer
There were four (4) events that caused five (5) outages during the month of October. The reportable outages disrupted power to 838 customers and resulted in a “total” SAIFI (frequency) index of 0.050 interruption per customer which was above the target of 0.005 for October. There were also 2 Major Events during the month of October.

September 2022 Reliability Frequency Index: Target = 0.010 Interruptions per Customer
There was one (1) event that caused one (1) outage during the month of September. The reportable outage disrupted power to 17 customers and resulted in a “total” SAIFI (frequency) index of 0.001 interruption per customer which was below the target of 0.010 for the month of September. There were no Major Events during the month of September.

August 2022 Reliability Frequency Index: Target = 0.006 Interruptions per Customer
There were five (5) events that caused five (5) outages during the month of August. These reportable outages disrupted power to 102 customers and resulted in a “total” SAIFI (frequency) index of 0.006 interruptions per customer and were below the target of 0.018 for the month of August. There was also one (1) major event that caused 3 separate outages during the month of August. On Saturday, August 6th at approximately 7 AM a contractor working at 215 S. Robson was operating an excavator that snagged a Cox cable TV high tension line. The line broke causing several poles to shock load, breaking a cross arm, and causing two (2) 4/0 copper powerlines to fall. Wires slapped into several streetlight heads causing them to burn up internally. Secondary neutrals and ground wires were damaged at numerous locations. The August SAIFI including major events was 0.317 minutes.

July 2022 Reliability Frequency Index: Target = 0.085 Interruptions per Customer
There were three (3) events that caused three (3) outages during the month of July. These reportable outages disrupted power to 68 customers and resulted in a “total” SAIFI (frequency) index of 0.007 interruption per customer and was below the target of 0.085 for the month of July. There were also one (1) major event that caused 12 outages during the month of July. Sunday evening on July 17, a monsoon storm combined with high winds and lightning caused several power outages in the Mesa electric service area and beyond. COM crews worked throughout the night on into the next day, making repairs and restoring power to the affected customers. Emergency response contract crews also assisted with the repairs the following day. The July SAIFI including major events was 0.514 minutes.

Lost-Time Accidents - Electric
The City of Mesa's Electric Utility has not had a lost-time accident since 8/13/2018. In the 2022 calendar year, Mesa Electric had no occupational injuries or work-related illness and therefore had no days of job transfer/restricted duty or days away from work. 
In accordance with our department's values to work safely, employees continue to communicate and use safe working practices as part of the daily activities, and safety topics are covered in the weekly tailgate sessions, as well as the monthly department meetings.
Core Business Process - Planning and Acquisition of Electric Energy Supplies
Core Business Process - Electric Business Development
Core Business Process - Electric Substation Operations and Maintenance
Core Business Process - Electric Transmission & Distribution Operations & Maintenance