The National Type Evaluation Program (NTEP) defines the United States type evaluation system for commercial measuring devices used in regulated transactions. Electric vehicle chargers used for billing must comply with National Type Evaluation Program (NTEP) legal-for-trade rules. Public charging depends on accurate kilowatt-hour measurement, which makes the National Type Evaluation Program (NTEP) central to regulatory trust.
Administration of National Type Evaluation Program (NTEP) falls under the National Conference on Weights and Measures and follows NIST Handbook 44 requirements. Enforcement of National Type Evaluation Program (NTEP) obligations involves state weights and measures agencies. EV chargers that bill per kilowatt-hour fall within the scope of National Type Evaluation Program (NTEP) certification. Legal-for-trade status, accuracy tolerances, sealing, and configuration control form the core aspects of the National Type Evaluation Program (NTEP).
Application, laboratory testing, software validation, and issuance of a certificate of conformance define the National Type Evaluation Program (NTEP) certification pathway. A certificate of conformance issued under National Type Evaluation Program (NTEP) confirms compliance for a specific charger model and firmware configuration. The distinction between National Type Evaluation Program (NTEP) and California Type Evaluation Program (CTEP) lies in jurisdiction, as CTEP applies only within California. Monta supports National Type Evaluation Program (NTEP)-aligned EV charging operations through configuration control and billing data integrity.
What is the national type evaluation program (NTEP)?
The National Type Evaluation Program (NTEP) is a U.S. certification program that evaluates and approves measuring devices used in commercial transactions. Administration of the National Type Evaluation Program (NTEP) is carried out by the National Conference on Weights and Measures in alignment with NIST Handbook 44. Legal metrology principles and oversight by state weights and measures authorities form the regulatory framework surrounding the National Type Evaluation Program (NTEP).
Legal-for-trade certification of devices that measure goods or services sold to consumers represents the primary purpose of the National Type Evaluation Program (NTEP). Measurement accuracy and consumer protection in commercial transactions define the core focus of the National Type Evaluation Program (NTEP). A defined type evaluation and approval process under the National Type Evaluation Program (NTEP) ensures uniform standards across jurisdictions.
Weighing devices, fuel dispensers, electric meters, and EVSE (Electric Vehicle Supply Equipment) fall within the scope of the National Type Evaluation Program (NTEP). Relevance of the National Type Evaluation Program (NTEP) to EV charging arises through the sale of electricity by the kilowatt-hour (kWh). Treatment of an EV charger as a commercial measuring device occurs under the National Type Evaluation Program (NTEP) when billing depends on kilowatt-hour measurement. An EV charger must be NTEP-certified if it is used in a commercial setting where customers are charged per kilowatt-hour. Certification under the National Type Evaluation Program (NTEP) confirms that an EV charger meets national standards for measuring and billing electricity sold to consumers and supports consumer billing transparency in public charging infrastructure.
Why does NTEP matter for EV charging?
NTEP matters for EV charging because it ensures that every kilowatt-hour delivered is measured and billed accurately. NTEP relevance arises because EV chargers that use kilowatt-hour (kWh)-based pricing are commercial measuring devices. The NTEP framework ensures accurate and verifiable energy measurement, legal compliance, and fairness in public charging transactions. NTEP certification supports legal-for-trade EV chargers in the United States.
NTEP importance increases when electricity is billed per kilowatt-hour rather than per session or per minute. Compliance with legal-for-trade requirements enforced by state weights and measures authorities is confirmed through NTEP certification. Absence of NTEP certification creates risks such as inaccurate billing, regulatory penalties, and loss of consumer trust. NTEP enforcement protects both drivers and operators by reducing disputes and strengthening consumer billing transparency. As states adopt kilowatt-hour (kWh)-based pricing mandates, the role of NTEP becomes more central to public charging stations.
NTEP value for charge point operators can be summarized to the following points.
- Enablement of kilowatt-hour (kWh)-based pricing models
- Regulatory compliance across jurisdictions
- Reduced compliance risk and potential fines
- Higher customer trust through transparent transactions
- Interstate deployment through uniform standards
The NTEP framework provides a standardized compliance path for commercial EVSE and expanding charging networks.
Who oversees NTEP compliance in EV charging?
The National Conference on Weights and Measures oversees NTEP compliance, while enforcement is carried out by state weights and measures authorities. NTEP administration occurs at the national level through NCWM. NTEP compliance in practice depends on state inspection and enforcement programs.
The National Conference on Weights and Measures (NCWM) administers NTEP and issues a Certificate of Conformance (CoC) for approved EV chargers. NCWM manages the type evaluation and approval process for commercial EVSE. NCWM aligns NTEP criteria with Handbook 44 requirements under legal metrology principles. An EV charger must receive a Certificate of Conformance (CoC) before it qualifies as a legal-for-trade device for kilowatt-hour billing.
NTEP-authorized laboratories conduct technical testing of EV chargers before certification. NTEP laboratory evaluation focuses on metering accuracy, software integrity, security of billing data, and compliance with Handbook 44 requirements. Testing results support NCWM review and approval decisions.
State weights and measures authorities perform field inspection and enforcement after deployment. State oversight activities include:
- Field inspections of installed chargers
- Legal-for-trade verification status
- Audit billing accuracy and labeling requirements
- Issuance of penalties or removal orders for non-compliant equipment
NTEP certification combined with state-level enforcement creates regulatory compliance across jurisdictions for commercial EVSE.
Which EV chargers require NTEP certification?
The EV chargers that require NTEP certification are listed below.
- Public charging stations that conduct commercial EV charging transactions based on the sale of electricity by the kilowatt-hour (kWh).
- Retail locations offering paid charging where customers are billed per kilowatt-hour under kWh-based pricing models.
- Highway corridor DC fast charging (DCFC) networks using kilowatt-hour (kWh)-based pricing for long-distance travel corridors.
- Third-party operated charging hubs that sell electricity directly to drivers in public charging infrastructure.
- Multi-unit dwelling (MUD) charging installations where tenants are billed for the sale of electricity by the kilowatt-hour (kWh).
- Fleet-access charging sites that resell electricity per kilowatt-hour to external drivers or commercial users.
- Mixed-use commercial sites that transition from free charging to kilowatt-hour (kWh)-based pricing.
The billing structure determines compliance requirements under legal-for-trade rules. Kilowatt-hour (kWh)-based pricing triggers NTEP evaluation in most jurisdictions. Per-minute billing models may avoid NTEP requirements in certain states, though state-specific regulatory nuances influence enforcement. Subscription charging models require analysis of whether the sale of electricity by the kilowatt-hour occurs within the pricing structure. State-level mandates that require kWh pricing increase the need for legal-for-trade EVSE and Handbook 44 compliance.
What are the key aspects of NTEP for EV charging?
The key aspects of NTEP for EV charging are the following.
- 1. Legal-for-trade status: An EV charger must obtain legal-for-trade status before it can bill customers per kilowatt-hour. Legal-for-trade EVSE approved for commercial use requires a valid Certificate of Conformance (CoC) issued through NTEP certification. Certificate of Conformance (CoC) validates that the charger model passed the type evaluation process. Operation of non-certified equipment may lead to enforcement action, removal orders, or penalties by state inspection authorities.
- 2. Accuracy tolerances: NTEP requires measurement accuracy within defined tolerances for kilowatt-hour billing. NTEP ensures that the kilowatt-hours displayed to the driver match the energy actually delivered within strict tolerance limits. Accuracy tolerances are defined under alignment with NIST Handbook 44 requirements. Testing verifies performance under different operating conditions to ensure accurate and verifiable energy measurement and billing integrity.
- 3. Sealing requirements: NTEP mandates tamper-evident sealing mechanisms for metering components and calibration settings. Sealing requirements prevent unauthorized adjustments that could affect billing accuracy. Physical or electronic seals protect parameters that influence kWh measurement verification. State inspection authorities verify seal integrity during field inspection and enforcement activities.
- 4. Configuration control: NTEP enforces controlled software and firmware configuration for commercial EVSE. Any modification to the metering or billing software must comply with NTEP configuration control requirements. Configuration control ensures that changes affecting metrology functions remain traceable and approved. Controlled software and firmware configuration protects the integrity of kWh-based pricing and billing logic.
- 5. Handbook 44 alignment: NTEP certification confirms that an EV charger complies with the applicable sections of NIST Handbook 44. Alignment with NIST Handbook 44 requirements ensures uniform standards across jurisdictions. Handbook 44 alignment supports legal metrology consistency and multi-state EV charging deployment.
NTEP regulates how EV chargers measure, record, and display kilowatt-hour usage in commercial EV charging transactions. NTEP certification defines the regulatory pillars that determine whether an EV charger qualifies for legal billing.
What are the benefits of NTEP certification for EV charging stakeholders?
The key benefits of NTEP certification for EV charging stakeholders are presented below.
- For charge point operators (CPOs):
- Enables legal-for-trade EV charging and kilowatt-hour (kWh)-based billing models.
- Reduces regulatory risk and potential fines through legal metrology compliance.
- Supports multi-state deployment with uniform standards across jurisdictions.
- Minimizes billing disputes through accurate and verifiable energy measurement.
- For EV drivers (consumers):
- Ensures consumer billing transparency in public charging networks.
- Builds consumer trust in public EV charging transactions.
- Protects against overbilling through energy measurement integrity.
- For hardware manufacturers (OEMs):
- Validates compliance with NIST Handbook 44 requirements.
- Enhances product credibility in regulated markets.
- Creates differentiation in jurisdictions that require legal-for-trade EVSE.
- For site hosts and property owners:
- Reduces liability related to incorrect billing practices.
- Ensures compliance with state enforcement authorities.
- Protects brand reputation through fair and transparent transactions.
- For regulators and authorities:
- Standardizes enforcement criteria across jurisdictions.
- Supports consistent legal metrology compliance.
- Strengthens consumer protection frameworks in commercial EV charging.
NTEP certification benefits stakeholders by aligning technical accuracy with regulatory compliance. NTEP certification establishes a legal-for-trade compliance framework that supports billing integrity and transparency. NTEP-certified EVSE strengthens regulatory certainty and operational scalability across public charging networks. NTEP certification supports future-proof charging infrastructure as kWh-based billing expands.
NTEP certification strengthens consumer confidence by ensuring that EV charging transactions are accurate and transparent. Operators that deploy NTEP-certified chargers expand across states without inconsistent measurement regulations. Manufacturers that adhere to Handbook 44 operate within a standardized and enforceable framework.
How does the NTEP certification process work for EV chargers?
The NTEP certification process for EV chargers works through a structured type evaluation and approval process that includes submission, laboratory testing, validation, and issuance of a Certificate of Conformance. NTEP process establishes a regulatory approval pathway for legal-for-trade EVSE and confirms alignment with Handbook 44 and legal metrology standards. NTEP certification applies to configuration-specific hardware and firmware versions that affect kilowatt-hour billing.
The NTEP certification process for EV chargers includes the following steps.
- 1. Submission: The manufacturer begins the process by submitting a formal application for type evaluation, including detailed technical documentation. Submission package includes metrology design, electrical schematics, software architecture, and firmware details. Controlled software and firmware configurations are documented through version control and parameter definitions. Documentation must demonstrate alignment with NIST Handbook 44 requirements. Hardware or firmware variants that impact measurement functions may require separate submission.
- 2. Laboratory evaluation: An NTEP-authorized laboratory conducts independent laboratory testing under controlled conditions. During laboratory evaluation, the EV charger is tested to ensure its energy measurements comply with Handbook 44 tolerances. Testing verifies measurement accuracy within defined tolerances across load ranges and environmental conditions. Independent metrology testing examines tamper-evident sealing mechanisms and configuration controls that affect billing integrity.
- 3. Validation: Evaluation results undergo verification of compliance with legal metrology standards. Review process confirms whether the EV charger meets legal-for-trade requirements. Non-conformities may require corrective design changes or resubmission. If the device meets all applicable requirements, the evaluation results are validated for certification approval.
- 4. Certificate of Conformance (CoC) issuance: Issuance of a Certificate of Conformance (CoC) follows successful validation. Once approved, the National Conference on Weights and Measures issues a Certificate of Conformance confirming the charger’s legal-for-trade status. Certificate of Conformance specifies model number, firmware version, and approved configurations. Certificate of Conformance supports deployment in commercial EV charging transactions and enables state inspection verification.
How is the NTEP application submitted?
The NTEP application is submitted by the EV charger manufacturer to the National Conference on Weights and Measures through a formal application for type evaluation that includes technical documentation, metrology specifications, and software details for review. The manufacturer initiates the NTEP application process for commercial EV charging approval. Authorized representatives may submit on behalf of the manufacturer when properly designated.
Each application applies to a specific hardware and firmware configuration intended for legal-for-trade EVSE use. Configuration-specific submission requires a finalized hardware design and a stable firmware version that affects kilowatt-hour billing functions. The application must clearly define the hardware model, firmware version control, and parameters subject to certification.
Technical documentation for metrology review must demonstrate alignment with Handbook 44 and legal-for-trade requirements. Submission package typically includes EVSE metrology design, electrical schematics, accuracy tolerances data, sealing descriptions, and billing logic documentation. Accurate and complete documentation supports regulatory review process efficiency and reduces resubmission risk.
Application submission completes the first stage of the Certificate of Conformance pathway and leads directly to independent laboratory evaluation.
How are EV charger metering systems tested under NTEP?
EV charger metering systems are tested in an NTEP-authorized laboratory through independent laboratory testing under controlled conditions to verify energy measurement accuracy, software integrity, sealing mechanisms, and compliance with NIST Handbook 44 tolerances. NTEP laboratory testing confirms that an EV charger measures delivered energy accurately under real-world operating conditions. Legal-for-trade verification depends on successful completion of this legal metrology testing stage.
During NTEP evaluation, the EV charger’s energy readings are compared against traceable reference standards to confirm compliance with Handbook 44 accuracy tolerances. Reference calibration equipment with known precision establishes baseline kWh values. Deviation between the charger reading and the reference standard is calculated and documented. Measurement accuracy within defined tolerances determines pass or failure. Any deviation outside the defined tolerance limits results in corrective action or reevaluation.
Load and performance testing covers the following areas.
- Testing at minimum and maximum current levels
- Testing under varying voltage conditions
- Testing across different power factors
- Verification at different charging durations
The device must maintain measurement accuracy across varying load and environmental conditions. Temperature variation and operational stress conditions are simulated to confirm consistency and repeatability of kWh verification.
Software and configuration assessment evaluates billing logic and metering calculations. Controlled software and firmware configuration is confirmed through version checks and parameter validation. Event logs and audit trails are reviewed to ensure billing accuracy and configuration control compliance.
Sealing and tamper protection testing examines tamper-evident sealing mechanisms that protect calibration settings. Access to metrology parameters is restricted and verified to prevent unauthorized modification. Only chargers that pass independent metrology testing are eligible for Certificate of Conformance eligibility and legal-for-trade status.
How are software and configuration validated for NTEP compliance?
Software and configuration are validated under NTEP by reviewing and testing the EV charger’s firmware, billing logic, security controls, and configuration management processes to ensure alignment with Handbook 44 requirements and maintain legal-for-trade measurement integrity. Under NTEP, any software that influences measurement or billing is considered legally relevant and subject to evaluation. Validation applies to a specific, controlled firmware version tied to the Certificate of Conformance (CoC).
Metrology software verification focuses on legally relevant software components that calculate and display kilowatt-hour values. The kilowatt-hour (kWh) calculation logic is evaluated for accuracy and consistency under defined operating conditions. Rounding methods, display formatting, and billing output are assessed to confirm billing integrity and transparency. Displayed energy values must match internally recorded measurement data used for transaction records.
Configuration control assessment includes the four elements below.
- Verification of controlled software and firmware configuration
- Unique firmware version identification linked to the Certificate of Conformance (CoC)
- Secure storage of calibration parameters
- Documented change management procedures for updates
Secure configuration management ensures ongoing compliance after certification. Secure access control restricts administrator permissions to authorized personnel. Audit trail functionality records configuration changes and access attempts. Tamper prevention mechanisms protect calibration and metrology settings from unauthorized modification.
Update and modification governance distinguishes regulated software from non-metrology components. Unauthorized changes to metrology-related software invalidate legal-for-trade status. Firmware updates that affect billing calculation logic or measurement functions may require reevaluation or amendment to the Certificate of Conformance. Each certified charger model remains approved only for its documented firmware version and configuration.
How is a certificate of conformance (CoC) issued under NTEP?
A Certificate of Conformance (CoC) is issued under NTEP in the following four steps.
- 1. Completion of laboratory testing: Completion of testing confirms measurement accuracy within defined tolerances under independent evaluation. Verification includes sealing integrity, configuration control, and software compliance. Successful testing establishes eligibility for legal-for-trade EVSE approval.
- 2. Submission of final evaluation report: Submission of a detailed evaluation report is performed by the NTEP-authorized laboratory to NCWM. Documentation includes test data, validation results, and compliance confirmation. Type approval documentation supports review for regulatory authorization.
- 3. NCWM technical review: Review by NCWM confirms alignment with Handbook 44 standards and all legal-for-trade criteria. Resolution of outstanding compliance questions occurs before approval. Approval identifies certified model number(s), certified firmware version(s), and any defined conditions of use. Configuration-specific certification applies only to the evaluated hardware and firmware combination.
- 4. Issuance and publication of the Certificate of Conformance (CoC): Issuance of a Certificate of Conformance (CoC) creates formal approval of legal-for-trade status. Assignment of a unique CoC number establishes a publicly verifiable compliance record. Publication in the public NTEP database enables state inspection verification. Only after receiving a CoC can an EV charger be deployed for commercial kilowatt-hour billing.
What is a certificate of conformance (CoC)?
A Certificate of Conformance (CoC) is an official document issued by the National Conference on Weights and Measures confirming that a specific EV charger model and firmware configuration complies with NTEP requirements and meets applicable NIST Handbook 44 standards for legal-for-trade use. A Certificate of Conformance confirms that an EV charger meets national legal metrology standards. A Certificate of Conformance serves as official proof of legal-for-trade compliance for commercial EV charging transactions involving kilowatt-hour (kWh)-based billing.
The Certificate of Conformance applies only to the specific hardware model and firmware version evaluated under NTEP. Configuration-specific certification ensures that billing accuracy and metrology controls remain tied to the approved design. Without a valid CoC, an EV charger cannot legally bill customers per kilowatt-hour in most states.
A Certificate of Conformance typically includes the following.
- Certified model number(s)
- Approved firmware version(s)
- Applicable device type, such as Level 2 or DC fast charger
- Defined conditions or limitations of use
- Unique Certificate of Conformance number
The Certificate of Conformance establishes alignment with NIST Handbook 44 standards and creates a publicly verifiable NTEP record. Publication in the public NTEP database enables state inspection authorities to confirm compliance during field inspections. State regulators rely on the CoC to verify that public charging stations operate within legal-for-trade standards. Hardware or software changes that affect metrology functions may require reevaluation or amendment to maintain legal-for-trade EVSE status.
What are the ongoing compliance obligations after NTEP approval?
The key ongoing compliance obligations after NTEP approval are listed below.
- Maintain configuration control:
- Ensure deployment matches the configuration-specific certification listed on the CoC
- Prevent unauthorized firmware or hardware changes
- Document and manage metrology-related updates
- Manage software updates carefully:
- Evaluate whether updates affect legally relevant software components
- Resubmit for evaluation if changes impact billing or kWh calculation logic
- Preserve controlled firmware version integrity
- Preserve sealing and tamper protections:
- Maintain tamper-evident sealing mechanisms
- Restrict access to calibration settings
- Ensure seals remain intact for state inspection readiness
- Ensure continued measurement accuracy:
- Maintain measurement accuracy within defined tolerances
- Address field issues that may impact kWh billing accuracy
- Cooperate with recalibration or corrective measures if required
- Comply with state inspection and enforcement:
- Provide access to state weights and measures authorities
- Present CoC documentation during inspections
- Correct deficiencies identified during audits
- Maintain billing integrity and transparency through accurate labeling
Ongoing compliance preserves regulatory authorization and protects consumer trust within the regulatory enforcement framework.
What are the common challenges in NTEP compliance for EV charging operators?
The common challenges in NTEP compliance for EV charging operators are summarized here.
- Managing configuration-specific certification:
- Ensuring deployed NTEP-certified EVSE matches the exact hardware and controlled firmware version listed on the Certificate of Conformance (CoC).
- Preventing field modifications that invalidate legal-for-trade status.
- Maintaining configuration control at scale across distributed public charging infrastructure.
- Handling software updates and feature releases:
- Determining whether updates affect legally relevant software components.
- Avoiding accidental non-compliance after billing logic changes.
- Balancing innovation speed with regulatory approval requirements and alignment with NIST Handbook 44.
- Navigating multi-state regulatory nuances:
- Managing variations in enforcement practices by state weights and measures authorities.
- Adapting to different timelines for kWh-based pricing mandates.
- Maintaining uniform standards across jurisdictions while complying with local requirements.
- Maintaining measurement accuracy in the field:
- Monitoring measurement accuracy within defined tolerances over time.
- Addressing environmental or electrical conditions that impact kWh-based billing compliance.
- Responding to customer billing disputes that question billing integrity and transparency.
- Ensuring sealing and tamper protection integrity:
- Preserving tamper-evident sealing mechanisms during maintenance.
- Training field technicians on legal metrology obligations and tamper prevention controls.
- Preparing for inspections and audits:
- Keeping CoC documentation accessible for review.
- Ensuring labeling and display information align with Handbook 44 requirements.
- Maintaining state inspection readiness across multiple sites.
Operational complexity of legal-for-trade EV charging increases as networks scale and regulatory risk exposure expands. Failure to maintain NTEP compliance can result in fines, forced shutdowns, or reputational damage.
What is the difference between NTEP and CTEP for EV charging?
The difference between NTEP and CTEP for EV charging is that the National Type Evaluation Program (NTEP) provides multi-state legal-for-trade certification, while the California Type Evaluation Program (CTEP) provides state-level certification required specifically within California. NTEP is administered by the National Conference on Weights and Measures. CTEP is administered by the California Department of Food and Agriculture through its Division of Measurement Standards under state-specific regulatory authority.
NTEP provides uniform standards across jurisdictions and supports legal-for-trade EV charging equipment in most U.S. states. CTEP governs legal-for-trade EV charging equipment deployed within California. Although both programs require alignment with NIST Handbook 44, CTEP operates under California’s independent regulatory authority and may require additional documentation or review. NTEP certification is not automatically valid in California.
Recognition and applicability differ between the two programs. NTEP is recognized by most U.S. states for legal-for-trade EVSE used in commercial kilowatt-hour (kWh)-based billing. CTEP is required for commercial EV chargers deployed in California under state-specific regulatory authority. Dual certification is often necessary for nationwide deployment strategies that include California.
Manufacturers seeking nationwide deployment often pursue both NTEP and CTEP approval as part of a multi-state compliance strategy. Deploying EV chargers in California without CTEP approval may result in enforcement action by state inspection authorities. Understanding jurisdiction-specific requirements reduces regulatory risk and supports compliant public charging infrastructure expansion.
How does Monta support NTEP-aligned EV charging operations?
Monta supports NTEP-aligned EV charging operations by enabling accurate kWh-based billing, maintaining configuration control, supporting compliant software management, and helping operators maintain inspection readiness across jurisdictions. While NTEP certification applies to hardware, Monta ensures that daily charging workflows remain aligned with legal-for-trade EV charging requirements. Monta functions as a legal-for-trade support framework for networks operating NTEP-certified EVSE.
Monta ensures billing integrity and transparency by securely processing metering data from certified chargers and preserving transaction records for audit trail documentation. kWh billing management within the Monta platform reflects certified measurement inputs tied to the Certificate of Conformance. Configuration control at scale is strengthened through centralized firmware governance, role-based access control, and traceable software management that protects legally relevant software components.
Monta enables an inspection-ready charging network by enabling exportable billing records and operational visibility for state enforcement authorities. Regulatory risk exposure is reduced by helping operators maintain uniform operational standards across jurisdictions as part of a multi-state compliance strategy. Monta alignment with NIST Handbook 44 principles supports scalable and compliant public charging infrastructure built on billing integrity and transparency.