Do You Need an Explosion-Proof or Type EE Floor Scrubber in a Hazardous Location?

Key takeaways

• In an unclassified area you need neither. OSHA says 1910.307 does not apply to sweepers and scrubbers used in nonhazardous locations.
• In Class I Division 2, Class II Division 2 and Class III areas, the minimum OSHA sets for electric trucks is Type EE, and OSHA has said it accepts scrubbers an NRTL approved to the truck standards.
• In Class I Division 1 and Class II Division 1, Type EE is not enough. The truck rule allows only EX there, and for hydrogen, acetylene and similar gases it allows no powered truck at all.
• Type EE means the motors and electrical equipment are completely enclosed. It does not mean explosion-proof. Tennant's own T600 EE manual says the machine "is not equipped with an explosion proof motor" and that its motor "will spark".
• An EE machine is for areas where the hazard is normally contained. If a spill or leak puts flammable vapor or dust in the air, stop the machine and keep it out.

It depends on the area's classification, and here is the split. In an unclassified area you need neither. In a Division 2 area (Class I or Class II) or a Class III area, a battery scrubber listed to UL 583 Type EE meets the minimum OSHA sets for electric industrial trucks. In a Division 1 area, Type EE is not allowed: the truck rule permits only Type EX, and an EE machine is not explosion-proof.

That last point is the one buyers get wrong. "EE" gets read as "explosion-proof electric," and the maker of the best-known EE scrubber says otherwise in its own manual. The Tennant T600 EE operator manual warns: "This machine is not equipped with an explosion proof motor. The electric motor will spark upon startup and during operation which could cause a flash fire or explosion if machine is used in an area where flammable vapors/liquids or combustible dusts are present." A Type EE label lets a scrubber into areas where the flammable material is normally sealed away. It does not make the machine safe in an ignitable atmosphere.

Which scrubber each location allows

OSHA has no rule written for scrubbers in hazardous locations. It has two interpretation letters, covered below, that point scrubber makers to the powered industrial truck standards, and the truck rule's table of which designations may go where (29 CFR 1910.178(c)(2)). Mapped onto the location definitions in 1910.399, that table gives this chart.

The division matters more than the class. Class I and Class II both allow EE in Division 2 and forbid it in Division 1. And some atmospheres take no powered truck at all: 1910.178(c)(2)(i) says "Power-operated industrial trucks shall not be used in atmospheres containing hazardous concentration of acetylene, butadiene, ethylene oxide, hydrogen" and a list of other gases. No rating fixes that. The chart covers battery machines; propane scrubbers fall under 1910.110(e), which the 1993 letter below points to.

What Type EE means, and what it does not

Type EE is one of the electric truck designations OSHA defines in 1910.178(b). Each adds protection to the one before:

• E: "minimum acceptable safeguards against inherent fire hazards."
• ES: E plus "additional safeguards to the electrical system to prevent emission of hazardous sparks and to limit surface temperatures."
• EE: E and ES plus "the electric motors and all other electrical equipment completely enclosed."
• EX: different in kind: equipment "so designed, constructed and assembled that the units may be used in certain atmospheres containing flammable vapors or dusts."

Compare OSHA's definition of explosion-proof apparatus in 1910.399: "enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure." Enclosing the motors is a safeguard for normal running. Withstanding an internal explosion is a different design. EE is the first, not the second.

That is why EE fits Division 2 and not Division 1. In Division 2 the gas or dust reaches the air only after something goes wrong: "accidental rupture or breakdown" of containers, "abnormal operation of equipment," or "infrequent malfunctioning" of dust handling. The EE machine is for normal days. On the abnormal day, a ruptured drum or a dust release, it has to stop and stay out. The T600 EE manual says not to operate the machine "in areas where flammable vapors/liquids or combustible dusts are present."

OSHA's position on scrubbers

The second source of confusion is that OSHA's truck rule does not technically cover scrubbers. OSHA has said so twice.

• June 8, 1993, letter to the General Services Administration. Sweeper/scrubber equipment "is not classified as a powered industrial truck and, therefore, need not meet any requirements for section 1910.178." Instead, for battery machines in non-hazardous locations "the battery chargers must be certified by an NRTL whether they are built-in or supplied separately," and in classified locations "the motors must be certified by an NRTL for use under the appropriate classification." It added that scrubbers intended for classified locations "should always be rated for use under the appropriate classification."
• April 3, 1995, letter to Tennant Company. Tennant asked to treat scrubbers as specialized trucks, or to allow designations lower than EE in "Class I, Division 2, Group D designated locations." OSHA pointed to the one place the truck rule already allows DS, ES, GS or LPS units, the storage locations in (c)(2)(v), and said scrubbers approved by an NRTL to "ANSI B56.1-1969, Standard for Powered Industrial Trucks, and NFPA No. 505-1969" will be accepted. Equipment "not listed or labeled by a NRTL for use in hazardous locations covered by the powered industrial truck standard must comply with 29 CFR 1910.307." And: "Section 1910.307 would not apply to sweepers and scrubbers used in nonhazardous (nonclassified) locations."

Put together: a scrubber is not a forklift, but in a classified location it is electrical equipment in a hazardous location, and 1910.307 applies unless the machine carries an NRTL truck listing for that location. A UL 583 Type EE listing is that route.

What 1910.307 asks of an unlisted machine

1910.307(c) allows three paths: equipment "approved as intrinsically safe"; equipment approved for the location, marked with its class, group and operating temperature, which may not exceed the ignition temperature of the gas or vapor present; or equipment the employer can demonstrate is safe for the location. A standard scrubber has sparking motors and no class or group marking, so only the third path is open, and the burden of proof is yours, not the dealer's. 1910.307(b) also requires classified areas to be "properly documented" (all Zone areas, and Division areas designated after August 13, 2007). That drawing tells you which row of the chart you are in.

The one listed EE scrubber, and its limits

Tennant's T600 EE brochure (8/23) says "Tennant is the only company that has a listed Type EE battery-powered floor cleaning machine," with approval "ETL Listed to UL 583 Type EE" for the U.S. and Canada only. It names uses in the "production, handling, processing and storage of hazardous materials such as perfumes, cosmetics, paints, printing inks, pharmaceuticals and rubbers," and adds: "It is the responsibility of the user to determine the suitability for use in the hazardous (classified) locations."

The EE is a fixed configuration of the 32 in T600 walk-behind, so check what you give up:

The charger is the gap buyers miss. The off-board charger is separate plug-in equipment, and the manual's warning that "batteries emit hydrogen gas" applies wherever you charge. Unless the charger is approved for the location, charge outside the classified area in a ventilated spot, as our floor scrubber safety guide describes. Charger certification for ordinary areas is in battery chargers.

What to do in a Division 1 area

Type EE is not permitted, and the T600 EE is the only listed EE scrubber its maker knows of, so the answer is usually a different tool. For dust, certified equipment exists: Nilfisk's combustible dust catalog lists vacuums "certified for use in hazardous environments, including Class I, Group D and Class II, Division 1 and 2, Groups E*, F, and G locations," plus air-operated models for where electricity is unavailable or undesirable. It lists no scrubber. Wet pickup in a Division 1 vapor area is a question for your safety engineer and the equipment maker, with the gas group in hand. Where the classified area is one room, run a standard fleet on the rest of the floor; our manufacturing plants guide covers that fleet.

Where this answer stops applying

• Outside the U.S. and Canada. This page follows OSHA designations, and the T600 EE's approvals are U.S./Canada only.
• Zone-classified sites. 1910.307 recognizes Class I Zones 0, 1 and 2, but the truck table is written in divisions. Ask the maker for a listing for your zone.
• Your local authority. Tennant says Type EE machines "are usually mandated by the Authority Having Jurisdiction (AHJ)," so the local authority can decide what goes in the room.
• What goes in the tank. A rated machine does not make a flammable cleaner safe; some freezer cleaners are flammable liquids (see the freezer floor guide). The manual also says not to "pick up flammable materials."

Bring the classification drawing to the dealer and ask for the listing in writing, by class, division and group. Our questions to ask a dealer cover the rest, and how to choose a floor scrubber handles sizing once the classification has narrowed the field.

Frequently asked questions

Sources

• OSHA standard interpretation, June 8, 1993, sweeper/scrubber equipment and powered industrial trucks: osha.gov
• OSHA standard interpretation, April 3, 1995, classification of sweepers and scrubbers (letter to Tennant Company): osha.gov
• OSHA 29 CFR 1910.307, Hazardous (classified) locations: osha.gov
• OSHA 29 CFR 1910.178, Powered industrial trucks, paragraphs (b) and (c)(2): osha.gov
• OSHA 29 CFR 1910.399, Definitions applicable to Subpart S: osha.gov
• Tennant T600 EE Operator Manual 9016606 Rev. 01 (02-2023): tennantco.com
• Tennant T600 EE brochure (8/23): tennantco.com
• Nilfisk, Combustible Dust Solutions catalog: nilfisk.com