APS and SRP Electrical Requirements for EV Charger Installation
Arizona's two dominant electric utilities — Arizona Public Service (APS) and Salt River Project (SRP) — each publish distinct interconnection and service requirements that govern how EV charger circuits connect to the grid. Understanding these utility-specific rules, alongside National Electrical Code (NEC) compliance and local permitting obligations, is essential for any residential or commercial EV charger installation in the Phoenix metro and broader Arizona service areas. This page details the electrical requirements both utilities impose, explains where their standards diverge, and maps the decision boundaries that determine which approval path applies.
Definition and scope
APS and SRP are not interchangeable entities. APS, regulated by the Arizona Corporation Commission (ACC), serves approximately 1.4 million customers across central and northern Arizona (APS service territory map). SRP operates as a political subdivision of the State of Arizona and serves roughly 1.1 million electric customers in the greater Phoenix area (SRP service territory); because SRP is a political subdivision, it falls outside ACC jurisdiction for retail electricity pricing.
Both utilities require that EV charger installations — particularly Level 2 EVSE operating at 240 V and 40 A or higher, and DC Fast Chargers (DCFC) — meet specific service entrance, metering, and load management conditions before energization. Their requirements layer on top of NEC Article 625 (Electric Vehicle Charging System), as defined in the 2023 edition of NFPA 70, Arizona's adopted building code, and municipal permitting rules. For a broader view of how Arizona's electrical regulatory framework is structured, see the regulatory context for Arizona electrical systems.
Scope limitations: This page covers utility-side requirements for APS and SRP service territories only. It does not address Tucson Electric Power (TEP), UniSource Energy Services, or rural electric cooperatives. Federal utility regulations (FERC, NERC) applicable to wholesale transmission are not covered. Commercial projects exceeding utility-defined thresholds may require separate demand-response or interconnection agreements beyond the scope described here.
How it works
When a property owner or electrical contractor plans an EV charger installation, the utility's role intersects with the project at three distinct phases:
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Pre-installation load evaluation — The contractor determines whether existing service capacity can support the new EVSE load. A standard residential service in Arizona is typically 200 A at 120/240 V single-phase. A 48 A continuous load (a common Level 2 EVSE rating) consumes 20% of that capacity before any derating. If the panel is undersized, a panel upgrade for EV charging may be required before the utility will authorize connection.
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Permit pull and utility notification — Arizona municipalities require an electrical permit for any new EVSE circuit. The permit application triggers a city or county inspection process, but APS and SRP each also require separate notification when new loads exceed defined thresholds. APS customers adding EV charging that may qualify for a time-of-use (TOU) rate must contact APS directly to enroll. SRP requires customers adding EV charging loads to notify the utility if the installation is commercial or if it affects metering configuration.
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Final inspection and energization — A licensed electrical inspector (municipal or county) must pass the rough-in and final inspection before the utility authorizes energization of any new dedicated circuit. Both utilities reserve the right to inspect metering equipment.
The how Arizona electrical systems works conceptual overview provides additional context on service entrance configurations and load calculation methodology.
Common scenarios
Residential Level 2 EVSE — APS territory
A homeowner in Scottsdale (APS territory) installing a 40 A, 240 V Level 2 charger must:
- Pull an electrical permit with the City of Scottsdale
- Install a dedicated circuit sized per NEC 625.41 (continuous load at 125% of EVSE nameplate) as specified in the 2023 edition of NFPA 70
- Verify the existing 200 A panel has capacity, or pursue an upgrade
- Contact APS to evaluate eligibility for the EV TOU rate (Rate E-32 or comparable current schedule); APS publishes current rate schedules at aps.com
Residential Level 2 EVSE — SRP territory
A homeowner in Mesa (SRP territory) follows an essentially parallel permitting path through the City of Mesa but notifies SRP through its EV rate enrollment process. SRP offers the EV Price Plan with off-peak charging windows designed to shift load away from Arizona's peak demand hours (typically 3–8 p.m. in summer months). SRP's metering for EV-specific rates may require a smart meter upgrade, which SRP installs at no charge in most cases.
Commercial DCFC installation
A commercial DCFC installation at 480 V three-phase requires a new service entrance in most cases. Both APS and SRP treat these as new commercial service applications, subject to their standard commercial service installation guides. For infrastructure-level details, see DCFC electrical infrastructure in Arizona. Load management systems, covered at EV charging load management systems, are often contractually required by the utility at this scale.
Multifamily properties
Multifamily EV charging installations involve sub-metering or master-metered configurations. Both APS and SRP have specific rules about how individual tenant EVSE loads are billed. The multifamily EV charging electrical design page addresses wiring topology for these scenarios.
Decision boundaries
The table below summarizes the primary differentiators between APS and SRP requirements for EV charger installations.
| Factor | APS | SRP |
|---|---|---|
| Regulatory authority | Arizona Corporation Commission (ACC) | Political subdivision; not ACC-regulated for rates |
| EV-specific rate program | Rate E-32 (residential TOU) | EV Price Plan (off-peak windows) |
| Threshold for utility notification | Per current APS service rules; contact APS for current load thresholds | Commercial installs and metering changes trigger notification |
| Smart meter requirement | May be required for TOU enrollment | SRP installs smart meters for EV plan enrollment at no charge |
| Peak demand window | Published in current rate schedule | Typically 3–8 p.m. weekdays, summer months |
| Governing electrical code | NEC 2023 edition (NFPA 70, 2023) as adopted by Arizona + local amendments | NEC 2023 edition (NFPA 70, 2023) as adopted by Arizona + local amendments |
For installations on the boundary between residential and commercial classification, or at properties near utility territory borders, the relevant municipal building department can confirm which utility serves the address. The Arizona EV charger electrical inspection checklist provides a structured review of the inspection points common to both utility territories.
Additional cost variables related to service upgrades and permit fees are detailed at cost factors for EV charger electrical installation in Arizona. Contractors working in Arizona must hold appropriate licensing; see electrical contractor qualifications for EV chargers in Arizona for licensing tier requirements. For wiring method specifics applicable across both territories, conduit and wiring methods for EV chargers in Arizona covers NEC-compliant installation approaches. The main Arizona EV Charger Authority resource index provides navigation to the full scope of technical topics covered in this network.
References
- Arizona Corporation Commission (ACC) — regulatory authority over APS as a regulated utility
- Arizona Public Service (APS) — Service Area Information
- APS Electric Rate Options
- Salt River Project (SRP) — Company Profile
- SRP EV Price Plan
- NFPA 70 — National Electrical Code, 2023 Edition, Article 625: Electric Vehicle Charging System
- Arizona Department of Fire, Building and Life Safety — Building Codes