A Class I, Division 2 high bay is not a standard high bay with better gaskets. It is a separately listed product: certified to a hazardous-location standard, built from materials chosen so the fixture cannot become an ignition source, wired through threaded entries instead of cord grips, and printed with ratings an inspector can check against your area-classification drawing. Sealing a standard fixture, adding a wire guard, or buying a higher IP rating does not make it legal in a classified area. This guide covers what actually changes between a standard industrial fixture and a certified Class I, Division 2 high bay or low bay, and what to verify on the spec sheet before you order.
Start with the Division, not the fixture
Class tells you what kind of hazard is in the air. Division tells you how often it is there. Division 1 means ignitable gas or vapour is present continuously, frequently, or during normal operation. Division 2 means it is present only when something goes wrong: a leak, a failed seal, a ventilation failure.
That difference changes the protection method. Division 1 fixtures contain an ignition inside a heavy housing. Division 2 fixtures prevent one, using sealed construction, controlled surface temperature, and non-sparking materials. A Division 1 fixture is always acceptable in a Division 2 area. A Division 2 fixture is never acceptable in Division 1, no matter how well built it is, which is why the Class I, Division 1 high bay range exists as a separate line.
The classification is not a judgment call you make on site. It comes off the area-classification drawing for your facility, produced by the engineer of record. If you want the full breakdown of Class, Division, Group, and T-code, the hazardous location classification guide covers each label in plain terms. Shorthand note: "C1D2" and the abbreviated forms you see in search bars and purchase orders all refer to Class I, Division 2. The code language uses Roman numerals.
The listing is the product, not a feature
The single biggest difference between a standard high bay and a hazardous one is the certification behind it. The EX-B high bay series is listed to UL 844 for hazardous locations, covering Class I, Division 2, Groups A, B, C, and D; Class II, Division 1, Groups E, F, and G; Class II, Division 2, Groups F and G; and Class III. Its compliance list also carries UL 1598 for wet locations, UL 1598A Marine Outside Type, and UL 924 emergency lighting.
A standard industrial high bay carries none of that, regardless of how sealed it is. IP66 is an ingress rating: it describes dust and water, not ignition risk. Two fixtures can share the same IP66 line on the spec sheet and only one of them can legally hang in a classified area.
Two things to check on your side. Match the Group to the worst-case gas or dust in the zone, since a Group D fixture is not acceptable in a hydrogen process. And confirm the certification mark the authority having jurisdiction accepts for your province before the order goes in. Provincial inspection differs across Canada, which the Quebec vs Ontario rules guide walks through.
What changes inside a Class I, Division 2 high bay
The construction differences are specific and they show up on the spec sheet:
- Copper-free aluminum housing. Standard practice in gas atmospheres, chosen to control the risk of an incendive spark from a struck surface.
- Stainless steel hardware, plus 1,000 hours of salt spray testing on the EX-B series, which is why the same fixtures show up in marine and offshore work.
- Threaded conduit entries. 3/4" NPT is standard on the EX-B, with 1/2" NPT, M20, or M25 available through an adapter. The entry has to be specified when the order is placed, not swapped in the field.
- Sealed optics and impact rating. IP66 with IK08 using the glass cover, and IK10 with the wire guard fitted.
- Controlled temperature. Ambient ratings are printed per model, and the nameplate T-code has to sit below the ignition temperature of the gas in your zone.
None of these are upgrades to a standard fixture. They are why the fixture is listed at all.
Output you do not have to give up
Hazardous-rated used to mean dim. It no longer does. The EX-B series runs four housings from 20 W to 400 W, with published lumen output from 2,600 lm on the smallest configuration up to 52,000 lm on the largest, at 130 lm/W for the regular clear-glass build and up to 140 lm/W across the family. Beam angles run 40, 60, 90, and 120 degrees plus T2, T3, and T5 distributions, CCT options run 2700K to 6500K depending on housing, CRI is greater than 70, and 0-10 V dimming is optional. Lumen maintenance is published at L70 beyond 150,000 hours at 55°C ambient, with a 5-year standard warranty.
For lower ceilings, the EX-Q1A low bay covers 20 W to 60 W with adjustable power and CCT, 3,000 to 9,000 lm at 150 lm/W on a 120 degree beam. In between, the EX-Q1/Q2 hazardous high bay spans 20 W to 200 W at up to 160 lm/W, with a 120-347 V input option that suits Canadian 347 V circuits directly.
One note if you are chasing a utility rebate: DLC qualification on these families is listed per product variation, not line-wide, so confirm it for the exact configuration you are ordering rather than assuming the series qualifies.
The math that does not change
Mounting height, spacing, and beam angle work the same way in a classified area as anywhere else. A Division 2 listing does not change how far light travels or how many fixtures an aisle needs. If you are sizing the layout itself, the LED high bay buying guide covers mounting height, lumens, and spacing, and the same rules apply to a hazardous fixture. What changes is that you cannot substitute a cheaper fixture from the standard industrial high bay range to close a budget gap once the area is classified.
Heat is a separate question from classification. A hazardous listing does not imply a high ambient rating, and a high-ambient fixture is not automatically hazardous-rated. If the mounting location runs hot as well as classified, both ratings have to be on the same nameplate. The high-temperature LED lighting line covers the ambient side of that.
Mounting and wiring in a classified area
Mounting options on the EX-B depend on the housing and driver cover selected: ceiling, wall, pendant, surface, and 25 degree stanchion. The EX-Q1A offers ceiling, surface, pendant, wall, and 25 degree stanchion the same way, with the driver-box cover chosen at order time setting which methods are available.
The wiring method matters as much as the fixture. Threaded entries, sealing fittings, and the right cable glands are where most hazardous installations fail inspection, and none of that is supplied with the luminaire by default. The hazloc installation basics guide covers seal-offs, glands, and conduit practice before the fixtures arrive on site.
What to have ready before you request a quote
- Class, Division, and Group from your area-classification drawing.
- T-code requirement, if your process specifies one.
- Mounting height and floor area the fixtures need to cover.
- Ambient temperature at the fixture location, not the general room temperature.
- Mounting method and entry size, since both are set when the order is placed.
- Supply voltage, and whether battery backup is required on any of the fixtures.
Send those six and we can match a configuration from the Class I, Division 2 high bay and low bay range, or run your dimensions through the free photometric layout service if you want fixture count and spacing calculated rather than estimated.
Common questions
Can I use a standard IP66 high bay in a Class I, Division 2 area? No. IP66 describes dust and water ingress, not ignition risk. A fixture is acceptable in a classified area only if it is listed for that classification, and the listing has to appear on the nameplate and the spec sheet. A sealed standard fixture with no hazardous listing fails inspection regardless of build quality.
Will a Class I, Division 1 fixture work in a Division 2 area? Yes. Division 1 protection always covers Division 2. It costs more and weighs more, so most facilities spec a Division 2 fixture where the drawing calls for Division 2, but there is no compliance problem with using the heavier one.
Is "C1D2" the same as Class I, Division 2? Yes, it is the shorthand used on purchase orders, in catalog navigation, and in search. The code language and the fixture nameplate use Roman numerals: Class I, Division 2.
Do I lose brightness with a hazardous-rated high bay? Not meaningfully at current efficacy levels. The EX-B family publishes up to 140 lm/W with output to 52,000 lm on the largest housing, and the EX-Q1A low bay runs 150 lm/W. Compare the published lumen figure for the exact wattage and diffuser you are ordering rather than comparing series to series.
Does a Class I, Division 2 high bay also cover combustible dust? Some do, and the marking tells you. The EX-B series is listed for Class II, Division 1, Groups E, F, and G and Class II, Division 2, Groups F and G alongside its Class I, Division 2 rating, plus Class III. Confirm the marking for the specific configuration you are ordering instead of assuming the whole line carries every rating.
How do I know whether my area is Division 1 or Division 2? From the area-classification drawing for the facility, prepared by the engineer of record. We spec fixtures against a classification, we do not assign one. If the drawing is out of date or missing for a zone, that gets resolved before fixtures are ordered, because the classification determines what is legal to install.
Sources: UL 844 hazardous-location listings and the published manufacturer spec sheets for the fixtures referenced above.
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