[152] In general terms, therefore, the result of these proceedings is that the Commission has misinterpreted Part 4 to the extent that it has not determined s 52T(1)(a) valuation of assets, allocation of common costs and treatment of taxation IMs for Electricity DPP regulation, and to the extent that it has not determined a SPA IM for Electricity DPP regulation.

[153] In terms of appropriate relief, the Commission filed useful submissions concerning the question of relief, were I to determine these proceedings in Vector‘s favour. Vector accepted that the approach set out by the Commission in those submissions was generally appropriate. I therefore consider that the appropriate relief is as follows:

[154] On that basis, none of the existing IMs determined by the Commission are rendered invalid.

[155] As noted at the outset, Vector is also a gas distribution business and the decisions in this proceeding will apply equally to the approach the Commission is required to take to the Subpart 10 DPP regulation of gas pipeline services.

[156] The question of costs is reserved.

(a) The Commission should specify valuation of assets, allocation of common costs and treatment of taxation IMs for Electricity DPP regulation. The Commission could do that by simply specifying the equivalent IMs for Electricity ID regulation as applicable to Electricity DPP regulation. As Vector suggested, any adjustment to the way those IMs are to be applied for Electricity DPP regulation could be indicated in the SPA IM. Alternatively, the Commission could specify separate such IMs for Electricity DPP regulation. That is a matter for the Commission.

(b) The Commission should, as it set out its submission on relief under the heading ―Third option – a stand-alone SPA IM‖, consult on, in terms of the consultation process provided by s 52V, and stipulate a stand-alone SPA IM for Electricity DPP regulation. For that purpose the period of time provided by s 52U needs to be extended: I reserve the question of the period of that extension, and invite further submissions from the Commission and Vector on that point. I record that I consider, as both the Commission and Vector submitted, that s 4(5B) of the Judicature Amendment Act 1972 provides me with appropriate powers.

(c) As the Commission further submitted on relief, merits review of that SPA IM would then be available and, on the making of the SPA IM, the time for a DPP reset/claw back under s 54K(4) for electricity lines services would begin to run again, if the new IM determinations had a material effect on the existing DPP.

[156] The question of costs is reserved.