EPA / CARB compliance

What each certification actually covers

EPA regulates the engine, not the generator. A portable generator’s engine is a small non-road spark-ignition engine, and at or below 19 kW it falls under 40 CFR Part 1054: exhaust limits for hydrocarbons plus oxides of nitrogen and for carbon monoxide, demonstrated over a declared durability period that commonly runs from 125 to 1,000 hours depending on displacement class and the category the manufacturer certifies to. A companion rule, Part 1060, governs the fuel system — low-permeation hoses and tanks, and on many units a sealed cap or a carbon canister.

CARB does the same job for California under Title 13 of the California Code of Regulations, with tighter limits and its own certification process. A compliant engine carries a CARB Executive Order number, and the emissions label on the engine states which standards it meets and for which model year. On a used unit, that label is the fastest way to check what you are buying.

Neither mark says anything about performance. EPA and CARB certification tells you nothing about output, total harmonic distortion, noise, build quality, or whether the unit has a carbon monoxide safety shutoff — that last one comes from ANSI/PGMA G300 and UL 2201, which are separate safety standards with no connection to emissions law. Conflating the two is the most common mistake buyers make with these labels.

The 49-state question, and buying across state lines

A “49-state” generator is EPA-certified but has no CARB certification, so it cannot be offered for sale as new equipment in California. Retailers enforce this at the shipping address: the same product page will accept an Oregon ZIP code and refuse a California one. It is a restriction on selling new equipment, not on ownership — a generator lawfully bought elsewhere and later moved into the state stays legal to own and use.

Buyers outside California sometimes choose CARB-certified models anyway. The honest arguments are resale into a larger market and the evaporative hardware, which noticeably cuts the fuel smell from a generator stored in an attached garage. The argument against is that CARB versions are occasionally a little more expensive or slightly derated for the same machine.

Aftermarket modification is where people break the rules without knowing it. The Clean Air Act prohibits tampering with a certified engine’s emission controls, and bolting a propane or natural-gas conversion kit onto a certified gasoline engine modifies the fuel system. To be legal on a certified engine, a conversion kit needs its own EPA certification — and a CARB Executive Order in California. Many kits sold online have neither and disclose it in small print. Factory dual-fuel and tri-fuel units are certified as sold, which is the clean way to get the same capability.

SORE, AB 1346, and what changes in 2028

California’s Small Off-Road Engine rules cover spark-ignition engines rated at or below 19 kW — mowers, blowers, chainsaws, pressure washers, and generators. Following AB 1346 in 2021, CARB adopted amendments setting emission standards of zero for new SORE equipment beginning with model year 2024, with portable generators and large pressure washers given until model year 2028 because no drop-in zero-emission replacement existed.

In practice that makes new gasoline portable generators unsellable as new equipment in California from that model year. It does not make existing ones illegal: owning, using, servicing, and privately reselling a generator you already have is unaffected. The visible consequences so far are the growth of large battery power stations, a marketing push toward propane and natural-gas standby units — stationary engines are regulated separately and are not SORE — and manufacturers keeping distinct non-California inventory.

Other states are worth checking rather than assuming. Federal law preempts most state small-engine standards but carves out California, and allows other states to adopt California’s non-road standards instead of writing their own. Few have done so for generators specifically, but the mechanism exists, and it is the reason “EPA-only is fine everywhere outside California” is a rule of thumb rather than a guarantee.

Standby generators fall under a different rule

A permanently installed home standby generator is a stationary engine, not a portable one. Spark-ignition standby units are certified under EPA’s New Source Performance Standards for stationary internal combustion engines, 40 CFR Part 60 Subpart JJJJ, and the manufacturer supplies the certification documentation with the unit. None of the SORE deadlines apply to them, which is part of why natural-gas standby has been the growth category in California.

Local air districts can add a layer on top. In some non-attainment areas a stationary emergency engine needs a permit from the local air quality management district, and those permits typically cap non-emergency running hours — the weekly exercise cycle counts against that budget. Installers usually handle the paperwork, but it is worth asking before the pad is poured.