Valuing multi-use digital grid infrastructure: Engineering architecture, regulatory legibility and verified capability

Digital-grid investment requires evidence that expenditure delivers network services and consumer value. Shared control platforms complicate attribution because infrastructure built for one obligation can support several functions. We examine the 2026 New South Wales Emergency Backstop Mechanism applications of Essential Energy, Endeavour Energy and Ausgrid through comparative documentary analysis and analytical illustrations. Published additional-response requirements increase by approximately 98% between October 2025 and October 2027, while reported incremental capex shares are 10.6%, 65.5% and 70.9%, respectively. These differences reflect expenditure composition within different price bases and cost boundaries, rather than comparative efficiency. The framework links architecture and incremental cost to required, enabled, available and verified capability, separating compliance cost recovery, economic appraisal and household financial effects. Pathway-specific measurement definitions distinguish responding-site percentages from delivered power. A source-based reconciliation identifies Essential’s $46.98 million net request and approximately $60.79 million before allowance adjustments. A hypothetical shared-platform appraisal yields a benefit–cost ratio of 0.9715, showing that reusability alone does not ensure positive net benefit. The study specifies the evidence needed to assess multifunctional investment and consumer-benefit claims. Realised NSW household benefits and regulatory undervaluation are not established by the dataset.