VAC · Volts alternating current
The unit naming conventional AC distribution down to server power supplies, the incumbent baseline that facility-level DC architectures are measured against.
Current numbers
±400 / 800 VDCDC bus voltages replacing the grounded 415/480 VAC neutral at high rack power (Mt Diablo / Diablo 400 is bipolar ±400 V about a grounded midpoint; NVIDIA / OCP 800 VDC designs run ungrounded/HRG or midpoint-referenced — see Ch 4.7)
+157%more power through the same wire gauge, 3-wire DC (POS/RTN/PE) vs 4-conductor 415 VAC — NVIDIA's Oct 2025 framing; its May 2025 basis gave ~85%. Topology-specific vendor comparison, not a constant
157% / ~61%more power through the same conductor (or less copper for equal power) moving from 415 VAC to 800 VDC distribution