Electric Reliability

Electric Reliability

The reliability of the city of Rocky Mount's electric system is evaluated using the following indices based on the number of sustained customer interruptions (i.e. those lasting longer than one minute). The city of Rocky Mount results for 2018 are as follows:

Value of Index Goal/Target 
SAIDI (Minutes/Year) 71.28 Less than 60 
CAIDI (Minutes/Year) 22.16 Less than 60
SAIFI (Interruptions per year)
3.22 Less than 1.00 
Explanation of Indices
  • System Average Interruption Duration Index (SAIDI): SAIDI represents the total outage time in minutes that every city of Rocky Mount customer experienced in 2015.

  • Customer Average Interruption Duration Index (CAIDI): CAIDI represents the average time in minutes for the city of Rocky Mount to restore power.

  • System Average Interruption Frequency Index (SAIFI): SAIFI is the average number of interruptions that a customer would experience annually.


Below is a comparison between Rocky Mount, NC Public Power and Rocky Mount’s surrounding utility providers. In the case of all indices, a lower number indicates better reliability.

Utility  Total # of
(in minutes)
(# of interruptions) 
(in minutes) 
Dominion 122,350 122 1.01 120.79
Duke Energy Progress (DEP) 1,353,328 166 1.35 122.96
Edgecombe-Martin County EMC 11,203 122.22 0.98 124.71
NC Public Power * 660,461 60.8 0.94 90.46
Rocky Mount 27,831 71.28 3.22 22.16

Public power is municipally-owned and operated electric service. More than 70 communities in North Carolina serve more than 400,000 residential, commercial and industrial customers. These communities are collectively known as NC Public Power. For the purpose of the indices, averages of all the utilities were used.