New Safety Requirements in UL 60335-2-79


New Safety Requirements in UL 60335-2-79

By Diane M. Calabrese / Published May 2020

Photo by iStockphoto.com/NataliaBulatova

Do you know everything that a manufacturer, distributor, or contractor really should know to be up to speed about UL 60335-2-79? Do you understand the scope, thrust, and reason for being of the safety standard? We bet that many, if not most, readers do.

But let’s try this for fun (and can’t we all use a bit of fun now and then)—a sort of self-test on things to know. Do you know them all? Then, tell us what we missed.

Here are ten things to know about 60335-2-79.


The transition to UL 60335-2-29 (from UL 1776) will be complete on March 1, 2021. (For a review of the standard and how it emerged, see the February CETA Edge column at www.cleanertimes.com/magazine/cleaner-times-articles-2/vital-resource-ceta-technical-committee.) Although UL 60335-2-79 is already in effect, beginning on the first day of March next year any design changes required in new equipment to comply with the standard must have been made. Until then, UL 1776-compliant equipment that is on the shelf can continue to be sold.


Like the safety standard it supplants, UL 60335-2-79 ensures that equipment is built in the safest possible way. It also aims to align to the fullest extent with expectations of standard IEC 60335-2-79, which is followed by countries around the world. In effect, it makes it easier to compare pressure washers made in different countries. The starting point will be that the machines all meet the same stringent requirements for safety; then, comparisons in capabilities and features can be made.


Testing of equipment by an NRTL, or nationally recognized testing laboratory, is a requirement for compliance with UL 60335-3-79 (just as it was for UL 1776.)  As of early March, there were 17 NRTLs in the United States. Among them are the familiar entities such as UL, Intertek, and CSA [Canadian Standards Association]. We know what NRTLs are, but from where did they spring? Read on.


The Occupational Safety and Health Administration (OSHA) created the NRTL program in 1988 and recognized the first NRTL in 1989. The program ensures that certain types of equipment be tested and certified for safe use. NRTLs are private-sector organizations that meet the legal requirements of 29 CFR 1910.7. Requirements are the capability to test and evaluate equipment for conformance with adequate controls and complete independence from client companies. NRTLs also must have procedures for addressing complaints and disputes with users.


Certification marks from NRTLs are unique and registered. After testing and certification, a manufacturer can apply a registered certification mark to its product. CFR 1910.399 and 1910.303, which OSHA administers, require testing of electrical equipment and an “acceptable” result. (Non-compliance can be very expensive, with fines upwards of $10,000.) Acceptability is easiest to demonstrate with testing and certification by an NRTL. However, there are special provisions in the regulations for custom-built equipment and equipment that cannot be tested under tests used by NRTL; in those instances, equipment must still meet the standards of the NEC (National Electrical Code).


Harmonization of standards used within countries and groups of countries becomes increasingly important as global trade increases and many companies seek and attain ISO (International Standards Organization) certification. (ISO is a shorthand way of acknowledging that so-designated entities have subjected their processes and procedures to verification; i.e., they are doing exactly what they ought to be doing and say they are doing and are doing it consistently.) Requirements for NRTL testing and certification buoy the harmonization process by demonstrating that a piece of equipment meets a safety standard. Standards such as UL 60335-2-79 and IEC 60335-2-79 can then be more easily compared, and with time perhaps totally harmonized—a worthy and still somewhat complicated goal. (IEC is the International Electrotechnical Commission.)


The ground-fault circuit interrupter (GFCI) is an essential player in safety of electrical equipment. The transition to UL 60335-2-79 maintains and enhances the expectations for the GFCI. To ensure that the operator of a machine does not become the conduit for electric current if there is a breach in the grounding path, the GFCI shuts off electric power in as little as 1/40 of a second. The GFCI has saved a minimum of hundreds of lives according to OSHA.


In the United States, a GFCI must be installed on all machines of 250 volts or less, single phase. It should never be removed, of course. Because pressure washers are among the pieces of equipment routinely used in a wet environment, breaches in equipment that allow any meeting of electrical current and water can be deadly. Test requirements for pressure washer components include a water spray test; which ascertains that a GFCI functions properly in the test, the spray should cause the device to interrupt the circuit. (Some history: NEC first required GFCIs on high-pressure spray washers in 1987—updated in 2014 to all 3-phase equipment rated 208Y/120 volts and 60 amperes or less, which is currently in UL 60335-2-79. Interestingly, NEC has required the GFCI for underwater pool lighting since 1968 and in bathrooms since 1975.)


Every expectation for safety established by UL 60335-2-79 is set to maximize performance of equipment in the context of maximum safety for operators. For instance, consider the length of a power cord. A power cord that is too short might encourage the very bad and unsanctioned practice of using an extension cord. Power cords can also be so long that they become trip and tangle hazards. Striking the right balance is what organizations setting safety standards grapple with regularly.


UL 60335-2-79 has some requirements not included in IEC 60335-2-79—and vice versa. For example, in the United States there is no requirement for sound and vibration markings.

Again, please tell us which technical topics should be covered in depth. Is there something that’s ambiguous, confusing, or just consternation-making? And we want to hear from everyone in the industry—manufacturers, distributors, suppliers, and contractors.

At times, requirements may seem so prescriptive they act as constraints. Yet that’s usually because we look at them in an immediate and familiar context.

Some safety standards may be established to meet one objective and later accomplish a different, unexpected one. Consider protection on pressure washers that stops wash water and chemicals from backing up and mingling with the water supply. Backflow protection has taken on heightened importance as the world strives to mitigate the effects of COVID-19. We want to be sure that wastewater, however unlikely it is to contain viral particles, is kept separate from potable water. COVID-19 viral particles are shed in fecal matter and get into sewage. Their viability there seems of short duration but caution rules.

Safety—the freedom from danger, injury, or damage in the dictionary definition—derives directly from the Latin for safe (salvus). No one expects a risk-free life. We reduce risks by doing the equivalent of picking the low-hanging fruit.

Disconnecting a GFCI is unsafe (and needlessly reckless). It’s the equivalent of not picking the low-hanging fruit.

By controlling the situations that are within our control day-to-day, we reduce risk. We also build up a reserve of energy to use when we most need it in unanticipated situations that are beyond our control.

Everyone has a role to play in staying calm and carrying on. It begins with adherence to the best practices in our industry. Ensuring that we all understand and comply with UL 60335-2-29 is a good foundation to build on. 

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