Industry — EV Charging
Charging hub electrical infrastructure from the utility service to the dispenser feeders
A DC fast charging site is a multi-megawatt industrial load placed in a parking lot, often on a utility service that was never sized for it. Apex engineers the medium-voltage service, transformers and 480 V distribution that feed the chargers, integrates load management with the charging network, and adds monitoring so operators see what the utility meter and each feeder are doing.
Operating realities
What makes ev charging distribution its own discipline
Utility service capacity and interconnection
A hub of 350 kW chargers can require several megawatts, which usually means a new medium-voltage service, a utility interconnection study and a long lead time on the utility side. Service voltage, metering location, transformer ownership and available fault current are settled with the utility before the electrical design can be finalized. Site selection without that conversation is a common cause of stalled projects.
Demand charges and load management
Peak demand sets much of the electricity bill, so the ability to limit total site demand while still delivering acceptable charge sessions is central to the business case. Load management can live in the charging network software, in a site controller or in both, and it has to be coordinated with the electrical ratings of transformers and feeders. The distribution equipment must be sized for the managed peak with margin, not for the sum of every charger nameplate.
Power quality and harmonic content
Charger power electronics draw non-linear current, and dozens of them on one transformer can push harmonic distortion toward utility limits and heat the transformer. Transformer K-factor or harmonic derating, neutral sizing and power-quality metering at the service are evaluated in design. Measured data after energization confirms whether mitigation is needed.
Outdoor equipment and public exposure
Switchboards, transformers and controls sit outdoors in publicly accessible areas, exposed to weather, vehicle impact and tampering. Enclosure ratings, bollards, clearances, ventilation and locked or tamper-resistant construction are part of the electrical design. Emergency shutoff and first-responder access requirements are coordinated with the authority having jurisdiction.
How Apex fits
LV, MV, automation and monitoring for ev charging
Low-voltage equipment
480 V switchboards and charger feeders
Apex engineers UL 891 switchboards for charger distribution, with feeder breakers sized and coordinated for the charger cabinets they serve, surge protection and metering at the service. Outdoor-rated enclosures and spare positions for future chargers are part of the layout.
Learn moreMedium-voltage equipment
Medium-voltage service and step-down transformers
Service at 15 kV class through metal-enclosed fused load-interrupter switchgear or metal-clad switchgear, depending on utility requirements and site scale, feeds dry-type or pad-mounted transformers stepping down to 480 V. Transformer specifications account for harmonic loading and the managed demand profile.
Learn moreAutomation & controls
Load management and site control interfaces
Site controllers interface the charging management system with metering and breaker status so total demand can be held within the utility service and equipment ratings. Where onsite storage or generation is present, the same controls manage charging, discharging and export limits; protective functions stay with the relays and breakers.
Learn moreMonitoring & analytics
Service metering and feeder-level visibility
Revenue-grade and power-quality meters at the service, plus feeder metering and breaker status, give operators and the charging network a shared view of demand, harmonic content and equipment condition. Data is available over Modbus TCP, or through the site controller's interface to the charging management system where applicable, and alerts help identify tripped feeders and failing equipment.
Learn moreTypical equipment
What a ev charging one-line usually contains
- 15 kV class metal-enclosed fused load-interrupter switchgear or metal-clad service switchgear
- Dry-type or pad-mounted step-down transformers with harmonic derating or K-factor rating
- 480 V UL 891 outdoor-rated distribution switchboards, 2,000 A to 4,000 A
- Feeder breakers coordinated with DC fast charger cabinet protection
- Site controller for load management integrated with the charging management system
- Revenue-grade and power-quality metering at the service entrance
- Surge protective devices and outdoor enclosures with tamper-resistant construction
- Battery energy storage interconnection for demand limiting where the project includes storage
Codes and standards that commonly apply
Specifications govern
- Electric vehicle power transfer systems commonly follow NEC Article 625, with service and distribution equipment under the general articles as adopted by the jurisdiction; the design engineer of record and the authority having jurisdiction govern.
- Switchboards are typically listed to UL 891 and dry-type transformers to UL 1561; charger equipment carries its own listings, commonly UL 2202 or UL 2594 depending on type, which the charger manufacturer is responsible for.
- Harmonic limits at the point of common coupling are often evaluated against IEEE 519 and the serving utility's interconnection requirements; the utility's rules govern the service design.
Questions we hear
Frequently asked
+How much utility capacity does a DC fast charging hub actually need?
It depends on the number and rating of chargers and on how much load management the operator will accept. Eight 350 kW chargers have a nameplate sum near 2.8 MW, but a managed site might be designed around a lower coincident peak. The service, transformer and switchboard are sized for the managed peak plus growth margin, and the utility interconnection study confirms what the grid can deliver.
+Why is a medium-voltage service usually required instead of a 480 V utility service?
Most utilities cap low-voltage services well below the demand of a multi-megawatt hub, and the fault current and voltage drop on a very large 480 V service become impractical. Taking service at 15 kV class and stepping down onsite gives the operator control over transformer sizing, location and future expansion. The trade-off is a longer utility lead time and medium-voltage equipment on the site.
+Does Apex supply the chargers?
No. Apex engineers and integrates the electrical infrastructure upstream of the charger cabinets: the service, switchgear, transformers, distribution, controls and monitoring. Charger selection is made by the site operator, and Apex coordinates feeder ratings, protection and communications with the charger manufacturer's requirements.
Related engineering resources
Read next
Standards & Codes
UL 891 Switchboards: Scope, Construction and Application
UL 891 is the listing standard for deadfront switchboards, the workhorse of service entrance and low-voltage distribution at 600 V and below. This article explains its scope, the construction and ratings behind the nameplate, how it relates to the NEC and NEMA PB 2, and the limits that push a project toward UL 1558 switchgear instead.
8 min read · Updated 2026-09
Digital & Monitoring
Power Quality Fundamentals for Distribution Systems
Power quality problems rarely announce themselves; they appear as tripped drives, warm transformers and unexplained resets. This article covers the disturbance categories defined in IEEE 1159, the harmonic limits in IEEE 519, the common causes and effects in commercial and industrial distribution systems, and the measurement and mitigation options available.
8 min read · Updated 2026-09
Equipment
Metal-Clad vs. Metal-Enclosed MV Switchgear
Metal-clad and metal-enclosed are not synonyms: metal-clad is a specific class of medium-voltage switchgear with construction requirements that metal-enclosed interrupter switchgear does not have to meet. Understanding the difference keeps specifications honest and prevents paying for, or missing, features the application needs.
7 min read · Updated 2026-09
Standards & Codes
NEC Requirements for Switchgear and Switchboards
The National Electrical Code (NFPA 70) sets installation requirements that shape how switchgear and switchboards are specified, laid out and labeled. This article walks through the articles an engineer meets on nearly every project, from Article 408 and working space to fault current marking, arc energy reduction and standby systems, with the reminder that the authority having jurisdiction and the adopted edition govern.
8 min read · Updated 2026-09
Apex Power Distribution · ApexPower.ai
Let's engineer the power system —
and the intelligence around it.
Send a one-line, a specification or a photo of what is installed today. An engineer reviews it and tells you what fits — equipment, protection, controls and monitoring — before anyone talks price.