Data Center Rack Systems & Power Feeds
Southern Electrical Services installs complete rack-level power distribution for data centers across Texas — from standard 30A single-phase branch circuits to 200A 3-phase feeds for high-density AI and GPU compute racks requiring 100kW or more per cabinet.
What Electrical Work Is Required for Data Center Rack Power?
Data center rack power feeds are the final distribution step in the facility electrical system — delivering power from PDUs and busway to individual server racks. Each rack requires at minimum one dedicated circuit (A-side), and redundant facilities require a second independent circuit (B-side) from a separate UPS/PDU path. As AI workloads push rack densities above 30kW, 50kW, and now 100kW+, electrical infrastructure must be designed for high-amperage 3-phase feeds, specialized rack PDUs, and overhead busway systems. Southern Electrical Services installs all rack-level electrical infrastructure as prime contractor throughout Texas.
Rack Power Distribution Services
Single-Phase Branch Circuit Installation
Standard rack power feeds for general compute environments — 20A and 30A circuits at 120V or 208V single-phase, run in conduit from floor PDUs or overhead tray to individual racks. We install circuits in quantity, maintaining consistent homeruns and documentation for every rack position. A 1MW data hall may require 500–1,000 individual branch circuits.
3-Phase High-Density Rack Feeds
High-amperage 3-phase power feeds for dense compute rows — 60A, 100A, and 200A circuits at 208V or 480V 3-phase for racks drawing 20kW through 200kW. AI server racks from NVIDIA (DGX H100, DGX GB200 NVL), HPE, Dell, and Supermicro increasingly require 3-phase feeds at 60A to 200A. We install properly sized conductors, conduit, and terminations for all high-density configurations.
A+B Redundant Power Paths
Installation of dual independent power paths (A-side and B-side) to each rack for Tier III and Tier IV compliance. A-side and B-side circuits originate from separate PDUs on independent UPS systems and generator branches — ensuring no single electrical fault can take down any rack. We document and label all circuits with complete power path traceability from utility source through to rack PDU.
Rack PDU Installation & Wiring
Installation of vertical and horizontal rack-mount power distribution units (PDUs) including metered, switched, and outlet-level monitored PDUs. We mount, cable, and terminate PDUs from Eaton, Vertiv (Geist), APC (Schneider Electric), and Server Technology — including high-density units rated from 15A single-phase through 60A 3-phase per PDU.
Overhead Busway & Starline Track
Installation of overhead busway systems for flexible rack power distribution — including Starline Track Busway, Eaton Universal Busway, and similar plug-in busway systems. Overhead busway allows rack positions to be powered, moved, or reconfigured without pulling new conduit or conductors. We install busway systems rated from 100A through 400A at 208V or 480V 3-phase.
Under-Floor Power Distribution
Conduit installation under raised access floors for traditional data center power distribution. We install conduit, conductors, and j-boxes per engineered drawings with precise documentation of every home run — critical for ongoing operations and future moves/adds/changes. Under-floor work requires careful coordination with cooling and cable pathways.
Power Feed Documentation & As-Builts
Complete circuit documentation for all rack power feeds — panel schedules, circuit maps by rack position, A/B path identification, conductor sizing records, and as-built drawings. Accurate documentation is essential for data center operations, capacity planning, and the moves, adds, and changes that happen throughout facility life.
Frequently Asked Questions
How much power does an AI GPU rack require?
AI GPU rack power requirements vary dramatically by configuration. A rack of legacy CPU servers may draw 5–10kW. A rack of GPU accelerators for machine learning may draw 20–40kW. A modern NVIDIA DGX H100 system draws approximately 10kW, while a full DGX GB200 NVL rack (72 GPUs) draws 120kW+. Hyperscale AI training clusters are now deploying racks at 200kW per cabinet. These densities require 3-phase 200A feeds and liquid cooling — air cooling is insufficient above approximately 30–40kW per rack.
What is A+B redundant power and which data center tiers require it?
A+B redundant power means each rack receives two completely independent power feeds — one from an A-side UPS/PDU path and one from a B-side UPS/PDU path. A and B sides originate from separate utility feeds, separate generators, and separate UPS systems. If any component on either path fails, the rack stays powered from the other path. Tier III and Tier IV data center certification requires A+B redundancy to all critical loads. Tier II may have partial redundancy. Southern Electrical Services designs and installs A+B infrastructure throughout Texas.
What is Starline Track Busway?
Starline Track Busway (and similar systems from Eaton and Legrand) is an overhead busway system with continuous tap-off capability — plug-in boxes can be added at any point along the busway without de-energizing the system. This allows data centers to add, move, or reconfigure rack power feeds without electrical shutdowns. Busway is rated for 100A to 400A and is particularly valuable for high-density rows or facilities with frequent reconfiguration. Southern Electrical Services installs and extends all major busway systems.
What circuit size is needed for a high-density AI rack?
For racks drawing 100kW at 208V 3-phase, the required circuit amperage is approximately: 100,000W ÷ (208V × 1.732) = 278A. Derated to 80% for continuous loads, the minimum circuit rating is 347A — typically served by two 200A circuits (one A-side, one B-side). At 480V 3-phase, the same 100kW load requires 120A circuits. Higher voltage (480V) allows smaller conductors and reduces distribution losses for very high-density deployments. Southern Electrical Services designs rack feed infrastructure for any density requirement.
Do you handle phased data center buildouts — fit-out one section at a time?
Yes. Most large data center projects are built in phases — infrastructure installed for the full eventual load, with fit-out of each white space zone as tenants or internal capacity needs grow. Southern Electrical Services structures our work to support phased fit-out: trunk conduit and feeders sized for full build-out, with branch circuits installed per phase. We maintain documentation that supports future phases by other contractors.
Rack Power We Install
- 20A / 30A single-phase circuits
- 60A–200A 3-phase circuits
- A+B dual power paths
- Rack PDU installation
- Metered & switched PDUs
- Starline Track Busway
- Eaton Universal Busway
- Under-floor conduit runs
- Overhead cable tray
- Panel schedule documentation
- As-built drawings
- Circuit labeling & tagging
Rack Power for Your Texas Data Center
From standard 30A branch circuits to 200A 3-phase feeds for AI GPU racks — Southern Electrical Services installs rack power infrastructure at any density, with full A+B redundancy, throughout Texas.