Is a UL mark legally required to sell a product in the United States?

For most consumer goods there is no federal law that requires a UL mark. The requirement usually comes from somewhere else: an OSHA workplace rule for equipment used by employees, the National Electrical Code adopted by a state or city, an authority having jurisdiction signing off a building installation, or a retailer and insurer contract. So the honest answer is "often yes in practice, rarely by federal product law".

Are the UL, ETL and CSA marks interchangeable?

When each mark is issued by a laboratory recognised by OSHA as an NRTL for the relevant standard, the marks are equivalent in regulatory weight. An Intertek ETL Listed mark to a given UL standard satisfies the same code or workplace requirement as a UL Listed mark to that standard. The market preference for the UL name is a commercial fact, not a legal hierarchy.

What is the difference between Listed and Recognized Component?

A Listed product is a complete end product tested against the full end-product standard and ready to be installed or sold as is. A Recognized Component is a sub-assembly (a power supply, a motor, a printed board) certified for use inside another product under stated conditions of acceptability. A Recognized Component mark on a sub-assembly does not by itself make the finished product compliant.

Does FCC authorisation cover product safety?

No. FCC equipment authorisation covers radio frequency emissions and electromagnetic compatibility under Title 47. It says nothing about electric shock, fire, energy or mechanical hazards. A device can hold a valid FCC ID and still have no recognised safety listing, which is the most common gap teams discover late.

Can a CB Scheme report be used to obtain a US listing?

Yes, and it is the usual shortcut. An IECEE CB test report and certificate, issued against the IEC base standard, can be submitted to an NRTL, which assesses only the US national differences instead of repeating the whole test campaign. This shortens the listing and lowers the cost when the IEC and UL standards are harmonised, as they are for UL 62368-1 and UL 61010-1.

Is the listing a one-off test or an ongoing obligation?

It is ongoing. After the initial evaluation the NRTL runs a Follow-Up Service, with periodic unannounced inspections of the factory to confirm that production still matches the tested sample. The right to apply the mark depends on staying in the Follow-Up program; it is not a certificate you obtain once and forget.

What standards does an NRTL test electronics against?

The relevant US national standard for the product type: UL 62368-1 for audio, video and IT equipment, UL 61010-1 for laboratory and measurement equipment, UL 60335 series and UL 60730 for household appliances and their controls, plus product-specific standards. Most of these are US national adoptions of the matching IEC standard with documented national differences.

NRTL / UL listing: US product safety explained

Author Hugues Orgitello Last updated 28 May 2026 ~13 min read

Guide · US product safety via NRTL listing

Teams shipping electronics to the United States usually plan for the FCC and then assume they are done. They are not. FCC authorisation covers radio emissions and electromagnetic compatibility; it says nothing about whether the product can catch fire, deliver a shock or store dangerous energy. US product safety lives in a separate world built around the OSHA Nationally Recognized Testing Laboratory program and marks such as UL Listed, Intertek ETL and CSA. This guide explains what that program is, why it exists, what "Listed" actually means, when a mark is genuinely required even though there is rarely a federal product law demanding it, and how a single CB Scheme report can feed the US listing instead of starting from scratch.

The split that surprises everyone: radio versus safety

The first thing to internalise is that the United States does not have a single product clearance like the European CE marking. It has two largely independent tracks, run by different organisations, under different legal instruments.

Concern	US authority / mechanism	Legal basis	Mark or identifier
Radio and EMC	FCC equipment authorisation	Title 47 CFR (FCC rules)	FCC ID or SDoC statement
Product safety	NRTL listing (UL, ETL, CSA, etc.)	OSHA, building codes, contracts	UL / ETL / CSA mark

The FCC pillar covers the radio side in detail. This guide is about the second row. The two do not overlap: a device can have a perfectly valid FCC ID and zero recognised safety evaluation. Conversely a passive product with no radio (a mains power supply, a motor controller, a luminaire) has nothing to do with the FCC but very much needs a safety story.

In Europe the two concerns are bundled under one self-declared regime: Directive 2014/53/EU (RED) wraps radio, EMC and safety into a single Declaration of Conformity the manufacturer signs alone. The US splits them, and crucially handles safety through third-party laboratories rather than self-declaration. That structural difference is the source of most planning mistakes.

Why the NRTL program exists

There is no federal agency that pre-approves the safety of ordinary consumer electronics before sale. Instead, the legal pressure comes through the workplace. The Occupational Safety and Health Administration (OSHA) requires, in its workplace regulations, that certain electrical equipment used by employees be "approved", and it defines approved as tested and certified by a Nationally Recognized Testing Laboratory.

An NRTL is a private laboratory that OSHA has formally recognised, for a defined list of standards, as competent to test and certify products for safety. OSHA does not test products itself and does not write the standards; it accredits the laboratories and publishes the scope of each recognition. The program therefore answers a simple question for an employer or inspector: can I trust that this equipment was independently verified against a recognised safety standard? If it bears the mark of an NRTL recognised for that standard, the answer is yes.

This is why the same physical mark carries weight far outside the workplace. Building inspectors, electrical inspectors, insurers and large retailers all lean on the NRTL system because it is the existing, government-backed definition of "independently safety-tested" in the United States.

"Listed" versus "Recognized Component"

The vocabulary matters and is routinely misused. The two core categories are distinct and not interchangeable.

Listed. A complete end product, evaluated against the full end-product safety standard, and authorised to carry the laboratory's Listing mark. A Listed product is ready to be installed or sold to an end user as a finished article. This is what a code official or retailer normally means by "UL".
Recognized Component. A sub-assembly or part (a switching power supply, a motor, a connector, a bare printed board) certified for use inside another product, under stated "conditions of acceptability". The Recognized Component mark (the backwards-RU symbol) tells the end-product engineer the part can be used, within limits, as a building block. It does not make the finished product compliant on its own.

A third, narrower category, Classified, covers a product evaluated only for specific properties (for example fire resistance) rather than against a full standard.

The practical trap: a manufacturer buys a Recognized Component power supply, sees a UL mark on it, and assumes the finished appliance is therefore covered. It is not. The end product still needs its own Listing (or its own end-product evaluation), although the Recognized Component status of the internal supply legitimately reduces the work, because that block is already characterised.

The main NRTLs and their marks

OSHA recognises a number of laboratories as NRTLs. The best known in electronics are below; the authoritative, current list with exact scopes is on OSHA's site.

Laboratory	Common safety mark	Notes
UL Solutions	UL Listed, UL Recognized Component	The most recognised name in the US market
Intertek	ETL Listed, ETL Recognized	Tests to the same UL and other standards; ETL mark is fully equivalent
CSA Group	CSA mark (with US indicator)	Strong for the combined US and Canada market
TÜV (SÜD, Rheinland)	NRTL mark within scope	Recognised for defined standard lists
MET Laboratories	MET mark	The first laboratory recognised under the program

The single most important point, and the one most often misunderstood: when issued by a laboratory that OSHA recognises as an NRTL for the relevant standard, the marks are interchangeable in regulatory terms. An Intertek ETL Listed mark to UL 62368-1 satisfies exactly the same code clause or OSHA requirement as a UL Listed mark to UL 62368-1. There is no legal ranking of NRTLs.

What is not equal is market perception. The "UL" name is so embedded in US procurement that some retail buyers, by habit or internal policy, ask specifically for it. That is a commercial preference to negotiate, not a legal obligation. If a contract literally says "UL Listed", an ETL or CSA mark may not satisfy that exact wording even though it is technically equivalent, so read the contract, not just the regulation.

The UL standards and harmonisation with IEC

NRTLs test against US national safety standards. For electronics, most of these are US adoptions of the matching IEC standard, published with documented "national differences".

Product family	US standard	IEC base	Replaces
Audio, video, IT and similar electronics	UL 62368-1	IEC 62368-1	UL 60950-1, UL 60065
Measurement, control, lab equipment	UL 61010-1	IEC 61010-1	-
Household appliances	UL 60335 series	IEC 60335-1	UL legacy appliance standards
Appliance controls	UL 60730 series	IEC 60730	-
Information / power over data	UL 62368-3	IEC 62368-3	-

The migration to UL 62368-1 mirrors the European move to EN 62368-1: the legacy split between IT equipment (UL 60950-1) and audio-video (UL 60065) was retired in favour of a single hazard-based engineering standard. For the engineering principles behind that standard, see the IEC 62368-1 guide. For the appliance branch see the EN 60335 household appliances guide; the UL 60335 series is the US sibling.

Because these UL standards are built on the IEC base, the technical core of a test campaign is shared across regions. That is exactly what makes the CB Scheme shortcut, covered below, so valuable.

The listing process step by step

Obtaining a Listing is a project, not a single test session. A typical sequence:

Identify the right end-product standard. Pick the US standard matching the product (for example UL 61010-1 for a benchtop measurement instrument). The wrong standard at the start wastes the whole campaign.
Pre-assessment and construction review. The laboratory reviews the schematic, the bill of materials, insulation system, spacings (creepage and clearance) and the safety-critical components. Internal parts ideally carry Recognized Component status.
Sample testing. Electric shock, energy, fire enclosure, heating, abnormal operation and fault conditions, dielectric strength, mechanical and stability tests as the standard requires.
Construction documentation. A controlled description of the product (the "follow-up procedure" or equivalent) that fixes exactly what was tested, so production can be checked against it.
Authorisation to mark. Once the product passes and the file is complete, the laboratory authorises the manufacturer to apply its Listing mark.
Enrolment in Follow-Up Service. The right to keep marking is conditional on the ongoing program described next.

A critical-component change, a different internal power supply, a new enclosure material, a layout change near safety spacings, generally triggers a re-evaluation of the affected part. The Listing is tied to the specific construction that was tested.

The Follow-Up factory inspection

This is the part with no European self-declaration equivalent and the part teams forget to budget for. A US listing is not a one-time pass; it is a continuing relationship.

After authorisation, the NRTL operates a Follow-Up Service: periodic, typically unannounced, inspections of the production site (or sites). The inspector confirms that what comes off the line still matches the sample that was tested, that safety-critical components are the ones declared, and that the markings are applied correctly. If production drifts, the right to apply the mark can be suspended.

This surveillance is structurally similar to a CE module D or H production-quality audit, but it is the default for every US listing, not an option reserved for higher-risk products. It is the mechanism that lets a single inspector, years later, trust a mark stamped on a unit they have never seen.

How this differs from FCC self-declaration and EU CE

It is worth laying the three regimes side by side, because the safety listing is the odd one out.

Aspect	EU CE (safety)	US FCC (radio)	US NRTL listing (safety)
Who declares conformity	Manufacturer alone (most products)	Manufacturer (SDoC) or via a TCB	Independent NRTL laboratory
Third party mandatory	Only for higher-risk categories	For intentional radiators (certification)	Effectively yes, for the mark to exist
Mark / identifier	CE marking	FCC ID or SDoC statement	UL / ETL / CSA mark
Ongoing surveillance	Only for some modules	Limited	Yes, factory Follow-Up by default
Legal driver	Product directives	Title 47 (radio)	OSHA, codes, contracts (rarely product law)

The contrast with the European self-declared default is sharp. Under CE, a manufacturer can place most electronics on the market by signing its own Declaration of Conformity; a third party is mandatory only for higher-risk categories. The US safety system, by contrast, is built around third-party laboratories from the start. And while the FCC offers a genuine self-declaration path (SDoC) for many devices, no equivalent self-declaration exists for the NRTL safety mark: by definition the mark belongs to the laboratory, not the manufacturer.

When is a mark actually required?

This is the question everyone asks: do I need UL? The accurate answer is layered, because the requirement almost never comes from federal product law for ordinary consumer goods. It comes from one of these:

OSHA workplace rules. If the product is electrical equipment used by employees in a US workplace, OSHA's "approved" requirement effectively demands NRTL certification. This is the original and strongest driver.
The National Electrical Code (NEC, NFPA 70) and building codes. The NEC, adopted into law by most states and many cities, repeatedly requires that equipment be "listed" or "labeled". A permanently installed luminaire, a panel, an EVSE charger, or wiring devices must be listed for an electrical inspector to pass the installation. See the NEC angle below.
The authority having jurisdiction (AHJ). The local inspector, fire marshal or code official who signs off an installation. Even where the wording is flexible, the AHJ in practice expects a recognised listing mark and can refuse to approve an unlisted product.
Retailers and marketplaces. Major US retailers and online marketplaces require a recognised safety mark as a condition of listing a product, independently of any law.
Insurers and liability. An unlisted product that causes a fire is a far worse position in litigation and insurance terms. The mark is, in part, risk management.

So for a battery-powered consumer gadget sold online, there may be no statute that forces a UL mark, yet the marketplace will require one. For a hardwired commercial luminaire, the NEC and the AHJ will require listing as a matter of law-via-code. The decision is therefore "who is my buyer and where is this installed", not "is there a federal product safety law".

The NEC and building-code angle

The National Electrical Code is the single biggest reason a safety mark becomes mandatory for installed equipment. The NEC is published by the NFPA as a model code and has no force by itself; it becomes law when a state or municipality adopts it. Once adopted, its repeated use of the words "listed" and "labeled" turns an NRTL listing into a legal precondition for the installation to be approved.

For anything permanently connected to building wiring, fixed luminaires, charging equipment, distribution gear, industrial control panels, the practical rule is: no listing, no inspector sign-off, no legal energisation. This is categorically different from a plug-and-play consumer device, where the pressure is commercial rather than code-based.

Feeding a US listing from a CB Scheme report

If you are also certifying for Europe or other markets, do not run the US safety campaign in isolation. The IECEE CB Scheme is designed exactly for this.

A CB test report (CBTR) and CB test certificate (CBTC) are produced against the IEC base standard by an accredited laboratory. Because the UL standards above are national adoptions of those same IEC standards, an NRTL can accept the CB report and then evaluate only the US national differences, rather than repeating the entire test programme. The shared IEC core is reused; only the delta is tested.

Step	Without CB report	With CB report
IEC base testing	Done as part of UL test	Already done, accepted
US national differences	Tested	Tested (the only new work)
Typical time	Full campaign	Shorter (delta only)
Typical cost	Higher	Lower

The savings are largest where IEC and UL are well harmonised (the 62368-1 and 61010-1 families). They shrink for product standards with heavy US-specific content. The accreditation chain behind both the CB laboratory and the NRTL is the same machinery described in the conformity assessment bodies and accreditation guide: an NRTL is, in effect, the US recognition layer on top of laboratory accreditation.

A clean sequence for a global product: scope the IEC base standard, run testing at a CB laboratory, obtain the CBTR/CBTC, submit to an NRTL for the US delta and to a European route for the SDoC or DoC, and to a CSA route for Canada (often combined with the US in a single CSA or cULus mark).

Common pitfalls

Assuming the FCC ID is enough. It covers radio only. A product can ship with a valid FCC ID and no safety listing at all, then get rejected by a retailer or inspector.
Confusing Recognized Component with Listed. A UL-marked internal power supply does not make the end product Listed. The finished article needs its own evaluation.
Treating the listing as a one-off. Forgetting the Follow-Up Service: production changes, an uncontrolled component substitution, or a missed inspection can invalidate the right to mark.
Reading "interchangeable" too literally against a contract. The marks are equal in regulatory terms, but a contract that literally specifies "UL Listed" is a wording problem, not a regulatory one.
Running US and IEC campaigns separately. Paying twice for the shared IEC core instead of feeding a CB report into the NRTL.
Picking the wrong end-product standard. Testing a lab instrument to the IT standard, or vice versa, wastes the whole campaign; the standard selection at step one is decisive.
Ignoring Canada. A US-only listing leaves Canada uncovered; a combined cULus or CSA mark usually costs little extra when planned from the start.

A worked example

Case: a mains-powered IoT gateway with Wi-Fi, sold to US enterprises and installed in equipment rooms.

The radio side goes through FCC equipment authorisation and yields an FCC ID, see the FCC pillar. That clears nothing on safety. Because the unit is mains-powered information-technology-class equipment, the applicable safety standard is UL 62368-1. The buyers are enterprises and the device is rack-installed, so a recognised safety mark is expected by both procurement and the facilities AHJ, even though no single federal statute mandates it for this device class.

The efficient route: run the safety campaign against IEC 62368-1 at a CB laboratory, obtain the CBTR/CBTC, then submit to an NRTL (UL, Intertek or CSA) for the US national differences to UL 62368-1, and enrol in the Follow-Up Service. Choose a combined cULus or CSA mark so Canada is covered in the same project. The same CB report also feeds the European DoC. One test core, three markets, three recognition layers.