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Unlike AC systems, which are backed by decades of robust, harmonized standards, DC systems remain relatively under-standardized. Existing DC norms are fragmented and application-specific, offering limited guidance for key aspects like protection coordination, short-circuit analysis, or selectivity—especially in multi-source, converter-based LVDC networks. The deliverable D2.2 presents a complete methodology for the design of protection systems in LVDC networks, developed within the Shift2DC project under the European Union’s Horizon Europe program. Due to the technical complexity and interdependence of the topics involved, the work has been structured into four complementary parts: A) Earthing Systems - The Earthing Systems Sub-Deliverable analyses the specificities of DC stray currents and their link to corrosion of metallic structures. It reviews different earthing configurations and provides recommendations for reducing corrosion risk, such as the use of TN-S or IT systems, along with verification and continuous monitoring. B) Protection Plan Methodology – This Methodology provides a structured approach for identifying, detecting, and isolating faults in LVDC networks. It covers protection philosophies, fault types, and selection criteria for protective devices — including both conventional (fuses, breakers) and emerging (solid-state) technologies — tailored to DC-specific challenges. C) Short-Circuit Current Calculation – This document introduces a simulation-based approach for determining prospective short-circuit currents in LVDC systems with multiple sources. It presents simplified models for common components and recommends time-domain simulations to support protection design in the absence of comprehensive DC standards. D) Selectivity in DC Systems - Finally, this sub-Deliverable explores how to ensure that only the faulted part of a DC network is isolated during a disturbance. It evaluates the applicability of AC selectivity principles, identifies the limitations of conventional methods in DC contexts, and examines emerging technologies like solid-state breakers and advanced protection schemes. Each part of these deliverable addresses a critical aspect of LVDC protection (earthing, planning, short-circuit calculation, and selectivity) forming a unified, standards-oriented methodology to ensure safety, reliability, and continuity in DC microgrids. This work contributes to Shift2DC’s goal of advancing interoperable and resilient LVDC systems. By addressing a key standardization gap, D2.2 supports WP5 on three levels: informing standardization efforts (T5.2), providing a validated technical basis for pre-standardization testing (T5.3), and contributing to the development of the strategic roadmap for DC deployment (T5.4). Its methodologies serve as concrete inputs for regulatory dialogue, technology validation, and harmonization activities.