800V DC data centre power

TOPIC HUB · 800V DC AI DATA CENTRE POWER

800V DC data centre power

The reference for practitioners on the 800V DC transition: architecture, standards, vendors, and economics. Anchored by NVIDIA + OCP Mt. Diablo v0.7.0 (March 2026) as the AI-density baseline; extended by IEC + UL + NEC in-progress work for 1500V DC and MVDC futures.

01Direct answer

800V DC data centre power is the direct-current distribution architecture at 800V (nominal) that AI-density facilities are adopting to feed 48V-input compute racks. It replaces the legacy 480V AC three-phase to 48V DC stack with a single MV-to-800V DC conversion at the perimeter (via solid-state transformer) plus 800V-to-48V conversion at the rack. This reduces the number of conversion stages (higher end-to-end efficiency), reduces copper (higher voltage, lower current), and enables sidecar power racks that separate power conversion from IT compute thermally + physically. The OCP Rack + Power working group's Mt. Diablo v0.7.0 specification is the current reference. NVIDIA's next-generation reference designs assume 800V DC facility feeds. Actual deployments are gated by insurance underwriter acceptance of higher DC voltages, availability of trained skilled electricians, standards-body publication of DC-specific safety codes, and vendor supply of solid-state transformers at the required scale.

02Key concepts

800V DC

Nominal facility-level DC bus voltage for AI-density power distribution.

Solid-state transformer (SST)

Layer 2 device that converts medium-voltage AC to 800V DC in a single stage.

Sidecar power rack

Layer 4 architecture: 800V-to-48V conversion in a physically separate rack adjacent to IT compute.

OCP Mt. Diablo

Open Compute Project's Rack + Power reference specification for sidecar-shaped 800V DC (v0.7.0, March 2026).

±400V bipolar

Alternative 800V-equivalent topology using bipolar positive/negative rails; near-term (2027-2028) adoption target.

1500V DC

Mid-term voltage-ceiling question for Layer 2-3 perimeter conversion (see Supplement C).

MVDC

Long-term utility-scale distribution at 5-15 kV DC; specific to campus-scale facilities.

OCP Rack + Power

Open Compute working group that publishes and maintains the reference specifications.

03Structural decomposition

The six-layer AI power stack

Layer 1. Utility interface + BESS (medium-voltage AC feed; grid-facing)
Layer 2. Perimeter conversion (MV AC to 800V DC via solid-state transformer)
Layer 3. Building distribution (800V DC bus + switchgear)
Layer 4. Rack-level conversion (800V DC to 48V DC via sidecar power rack)
Layer 5. In-rack distribution (48V busbar to compute blades)
Layer 6. Point-of-load (48V to sub-1V @ die via POL silicon)

04Deep-dive research

The Architecture MapFoundational six-layer framework for the entire series.
800V DC vs OCP Mt. DiabloTwo distinct architectures both called "800V DC" and how to tell them apart.
Why data centres are going DCThe efficiency + reliability drivers beyond capacity.
Arc behaviour + insuranceLayer 3 protection regime and the insurance underwriter constraint.
Supplement A. The Transition TaxLayer-by-layer capex premium decomposition.
Supplement B. Hybrid ForeverWhy most facilities will run mixed AC/DC through 2035+.
Supplement C. The Voltage Ceiling1500V DC and the MVDC question.
Supplement D. The Solid-State TransformerLayer 2 supplier dynamics: Western vs Chinese SST.
Supplement E. The Sidecar Power RackLayer 4 architecture + OCP Mt. Diablo ecosystem.
Supplement F. The Connector WarsLayer 4/5 interface: high-current DC connectors.
MVDC / LVDC Architecture MapLiving index of vendor coverage across DC voltage classes.

05Standards + regulation

OCP Rack + Power (Mt. Diablo v0.7.0)Current reference specification for 800V DC AI-density rack architecture.
IEC 60947-10 (SSCB), IEC 62477-1, IEC 60364-7-712International safety + protection standards; 1500V DC extensions in progress.
UL 98B (DC disconnects), UL 1741 SB (grid interconnection)North American safety certification; 1500V DC extensions in progress.
NEC 2026 (NFPA 70)Adds partial 1500V DC coverage in 2026 edition. State adoption rolling through 2026-2028.

06Commercial + investment implications

Commercial + investment angles

The 800V DC transition is a specific capex + supplier-concentration lens on AI infrastructure. See Supplement A: The Transition Tax for layer-by-layer capex decomposition and Supplement D: SST vendor dynamics for the specific Layer 2 supplier concentration risk. For PE sponsors evaluating power-electronics or SST acquisitions, this is the primary market thesis. For hyperscaler strategy teams specifying facilities that commission 2027-2029, this is the primary architecture decision.

07Frequently asked

Why 800V and not another voltage?

800V is the specific voltage where AI-density economics work: high enough to reduce copper cost + conversion stages materially vs 480V AC baseline, low enough that Western insurance underwriters + skilled electricians can accept it today. 1500V DC offers further copper reduction but faces standards + workforce readiness constraints (see Supplement C).

Is 800V DC the same as OCP Mt. Diablo?

No. 800V DC describes the voltage class + broader architecture; Mt. Diablo (v0.7.0) is one specific reference implementation for the Layer 4 sidecar power rack. NVIDIA reference designs assume 800V DC facility feeds; Mt. Diablo specifies how Layer 4 (rack-level) is built to accept those feeds. See Two Architectures Wearing the Same Name.

When will 800V DC be mainstream for new AI data centre construction?

2027-2029 for hyperscaler AI-density greenfield. Earlier for high-density pilots (2026). Later for mid-cap operator + colo (2028-2030). See DC-DC Transition XIII: Ten-year view.

What is the biggest supplier-concentration risk?

Solid-state transformers (Layer 2). Four Western vendors (Eaton, Schneider, ABB, Hitachi Energy) plus three Chinese entrants (CRRC, TBEA, BYD) constitute the entire supplier universe. See Supplement D.

Where does 1500V DC or MVDC fit?

Mid-to-long term. 1500V DC offers ~30% additional copper savings vs 800V DC but faces standards (IEC 60947-10, UL 98B extensions in progress), workforce, and insurance constraints. MVDC (5-15 kV) is campus-scale utility distribution, not in-facility. See Supplement C.

How does 800V DC change insurance + safety?

Materially. Arc behaviour at 800V DC is different from 480V AC (see DC-DC IV: Arc Behaviour + Insurance). NFPA 70E arc-flash guidance applies but DC-specific insurance underwriter acceptance is the practical gating factor.

08Further reading

Full series: The DC-DC Transition (19-piece flagship). Adjacent hubs: AI Power Semiconductors, AI Data Centre Cooling, AI Data Centre Interconnection. Living Index: MVDC / LVDC Architecture Map.

Definition 800V DC data centre power is the architecture that distributes 800-volt direct current from a facility bus to rack-level shelves, replacing the traditional 415V AC facility distribution. It is driven by AI compute rack density above 100 kW where 48V DC distribution copper mass becomes uneconomic.

800V DC data centre standards (Aug 2026 status)
Standard / architecture	Sponsor	Topology	Status	Vendor design-wins
OCP Mount Diablo v0.5	Microsoft + Meta + Google	Bipolar ±400V (800V pole-to-pole)	Draft published Mar 2026	Delta, Vicor, Vertiv, Schneider
Nvidia 800V (Blackwell/Rubin)	Nvidia	Unipolar 800V DC (0-800V rail)	Production spec 2025-2026	Delta, Vicor, Empower Semi, MPS
Legacy 415V AC (comparison)	IEC / IEEE	Three-phase AC	Existing (mature)	Universal
HVDC facility distribution (adjacent)	None (custom)	±10 kV DC (facility-to-substation)	Research / pilot	ABB, Hitachi Energy, Siemens