FortisBC Inc. (FortisBC) Application for a Certificate of Public ...

In Figure 9, the three fittings, 12-L1, 12-S0 and 12-R1 are drawn for comparison
purposes. It is probable that the 12-R1 Iowa curve would be selected as the most
representative of the plotted survivor characteristics of the group.
Survivor Curve Judgments. The survivor curve estimates were based on judgment
which considered a number of factors. The primary factors were the statistical analysis of
data; current policies and outlook as determined through conversations conducted as part
of this study with operations and management personnel; incorporating the knowledge that
Gannett Fleming has gained through the completion of a number of Fortis assignments
over a number of years; and survivor curve estimates from previous studies of this
Company and other electric distribution companies.
Appendix BCUC IR1 69.4
Account 365.00 - Distribution Conductors and Devices, represents 17% of the
depreciable plant studied. The retirements, additions and other plant transactions for the
period 1960-2009 were analyzed by the retirement rate method. The original survivor curve
as plotted on page IV-46, indicates retirement ratios that begin to increase at age 13 and
continue with high retirement ratios thereafter. Staff interviews did not indicate any
significant reason that the future retirement patterns will vary from those experienced in the
past. While it is considered that this account will experience growth over the next few
years, given expected growth in the distribution service areas, the historic retirement trends
are expected to continue into the future. The life of this account has been increased from
40 to 45. As such, the Iowa 45-R3 selected for this account fits well to the historic
retirement patterns and is expected to be indicative of the future retirement patterns.