Selling EV Charging by the Kilowatt-Hour: Weights and Measures Certification Rules for HOAs

Most HOA boards focus on whether they can charge residents for electricity, and how much. Fewer realize that the method they choose to bill can pull the project under a whole separate body of law: weights and measures regulation. This is the same category of rules that governs gas pumps, grocery scales, and taxi meters. The moment a device measures a commodity and money changes hands based on that measurement, the government treats it as a commercial measuring device that must be accurate and, in many states, officially certified.

For EV charging, the trigger is billing by the kilowatt-hour (kWh) — the unit of electricity. If your community sells power to residents priced per kWh, the charger is acting as a commercial meter. If instead you bill a flat monthly fee, charge by the minute or hour of session time, or simply fold charging into HOA dues, you are generally not selling a measured commodity and these rules usually do not apply.

This distinction matters because it can quietly reshape which chargers your board is even allowed to buy, and it is easy to miss until an installer, a state inspector, or a resident dispute brings it up.

The national rulebook for commercial measuring devices is NIST Handbook 44, published by the National Institute of Standards and Technology. In 2017 the standards body that maintains it added a section covering Electric Vehicle Fueling Systems, which sets accuracy requirements for chargers that sell electricity by the kWh. The typical accuracy tolerance is plus or minus two percent, meaning the energy the resident is billed for must be within two percent of what actually flowed to the car.

Backing that up is the National Type Evaluation Program, or NTEP, run by the National Conference on Weights and Measures. NTEP tests a charger model and, if it passes, issues a Certificate of Conformance. Think of it like a UL listing, but for measurement accuracy rather than electrical safety. A charger with an NTEP Certificate of Conformance has been proven to measure energy accurately enough to be sold commercially.

The important takeaway for boards: earning that certification is the manufacturer's job, not yours. Your board's responsibility is simply to buy a model that already carries the certification when your state requires it. That is why the specification you hand your installer matters so much.

Weights and measures law is enforced at the state level, so the rules and timelines differ depending on where your community sits. States adopt Handbook 44 on their own schedules, and enforcement has rolled out unevenly. Some states actively require certified chargers for any per-kWh sale today; others have adopted the standard but are not yet inspecting EV chargers; and a number have not adopted the EV section at all.

California is the most advanced example. Its Division of Measurement Standards, part of the state Department of Food and Agriculture, requires chargers that sell electricity by the kWh to be type-evaluated and certified, and it charges an annual device registration fee for each commercial charging port. New York, Washington, and several other states have moved in the same direction. Because this landscape changes year to year, the safest step is to confirm your state's current position before you finalize a billing model.

You can check with your state's weights and measures or agriculture department, and your installer or charging vendor should also be able to tell you whether a given model is NTEP certified and what your state currently enforces.

The practical risk is buying hardware that cannot legally bill the way you intended. Many capable, popular Level 2 chargers are not NTEP certified, because certification adds cost and most residential-style units were never designed for commercial per-kWh sales. If your board settles on kWh billing and then discovers the installed chargers are not certified in a state that requires it, you could face the choice of switching your billing method or replacing hardware — both painful after the fact.

There are two clean paths. The first is to require, in writing in your RFP and purchase order, that all chargers carry a current NTEP Certificate of Conformance for EV fueling systems. The second is to deliberately choose a billing method that avoids the requirement altogether, such as per-hour session pricing or a flat monthly stipend added to the resident's account.

For many smaller communities, the second path is simpler and cheaper. Per-hour billing still discourages people from leaving a car parked at a charger all day, still recovers cost, and sidesteps the certification and device-fee overhead entirely. Larger communities that want the fairness of paying for exactly the energy used will more often go the certified-device route.

Getting this right is mostly about sequencing decisions in the correct order. Decide how you want to bill before you pick hardware, not after, because the billing choice narrows the eligible equipment. Then verify the legal requirement in your state, and put the certification requirement in writing so the obligation sits with your vendor, not your reserve fund.

Keep documentation. If you buy certified devices, file the Certificate of Conformance numbers with your charging records so a future board or a state inspector can confirm compliance without a scramble. If you register devices with the state, calendar the annual renewal so registrations do not lapse.

Weights and measures certification is not a reason to abandon EV charging or even to abandon usage-based billing. It is simply a rule to plan around. The cost of certification is carried by the manufacturer and reflected in the hardware price, and the annual device fees where they exist are modest — typically a small per-port charge each year rather than a major budget line.

The expensive mistake is discovering the requirement after installation. A board that decides its billing model early, checks its state's rules, and writes the certification requirement into the contract avoids that trap entirely. Whether you land on certified per-kWh metering or a simpler per-hour or flat-fee model, making the choice deliberately keeps your project compliant and your residents confident that they are being billed fairly.