Examination Procedure Outlines (EPOs) - Overview of the Two Standards

EPO-52: EVSE Field Evaluation Procedure

Full Title EPO-52 – Electric Vehicle Fueling Systems (EVFS): Evaluation Procedure for Type Evaluation and Field Inspection

Issued by: CDFA Division of Measurement Standards (DMS) – California

Primary Purpose: Defines how an EVSE is evaluated for approval (e.g., design, labeling, sealing, functionality) before being placed in service.

Who Uses It: County Sealers, Service Agents (SA), Registered Service Agencies (RSA) – when performing initial inspection or certification.

Focus: Administrative & design compliance — ensuring the charger meets all approval, identification, safety, and audit requirements.

EPO-30: Retail Electric Vehicle Fueling Systems

Full Title EPO-30 – Retail Electric Vehicle Fueling Systems: Test Procedure for Commercial Measurement

Issued by: NIST (and adopted by CDFA) – National Model Procedure

Primary Purpose: Defines how an EVSE is tested for accuracy during commercial operation (energy measurement, price computation, timing, etc.).

Who Uses It: Inspectors, Sealers, or field technicians verifying accuracy and compliance of retail systems after installation.

Focus: Performance and accuracy compliance — ensuring the charger measures energy and computes price correctly.

Link: https://cdn.ncwm.com/userfiles/files/Exams/Reference%20Material/NIST%20EPO%2030.pdf

In Plain Terms

  • EPO-52 = “Can this charger legally operate and be sealed?”→ It focuses on ID, markings, software version, safety, and configuration approval.

  • EPO-30 = “Does this charger bill customers correctly?” → It focuses on energy accuracy, price calculation, timing, and performance tolerance.

Key Tests / Checks - Nameplate & certificate verification

  • Software identification

  • Security seal & event log check

  • Display / operation review

  • Full energy accuracy testing (AC & DC)

  • Pricing & timing validation

  • Multiple rate / MMQ checks

  • Tolerance compliance (HB 44 Table T.2)

    |Timing of Use | Before or immediately after an EVSE is placed in service (“type evaluation” or “initial verification”).
    | During routine inspections, complaint investigations, or annual testing of active commercial EVSE. |

    | Scope | Any EVSE seeking CTEP/NTEP approval or first-time field verification. | Only commercial EVSE systems in use for public charging and energy sale. |

    | Units Covered | AC Level 1, Level 2, DCFC, fleet and public | Primarily retail public-access AC/DC charging units |

    | Outputs / Records | Compliance checklist for CTEP approval (markings, seals, nominal values, event log, MMQ, etc.) | Measurement and tolerance test record (error %, test loads, price verification, time fee validation, etc.) |