Electricity Asset Management Plan 2019-2029
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Figure 4-20 Age Profile for 22 and 11 kV Distribution Cables by Type
Condition and Health We are experiencing an increase in the number of faults on certain sections of cables based on a 5-year rolling window. Tests have also shown a number of cables with very low insulation resistance values and this indicates that we have a certain population of cables that is approaching end of life. Another failure mode that is on the increase and causing outages is deteriorating tinning on tinned aluminium lugs on outdoor 11 kV cable terminations on 11 kV cable risers to OH lines. Age profiles of our 22 kV and 11 kV underground fleet are given below.
Figure 4-21 Fault rate for 11 kV Distribution Cables
Strategy Because of high load density and criticality, the HV distribution network in the Auckland CBD has over the last decade and a half been progressively upgraded from the existing 11 kV network to a 22 kV network and subject to the availability of 22 kV cables in a street, all customer capacity upgrades and new connections within the CBD will be at 22 kV. This
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