7.2 Commercial Garages, Motor Fuel Dispensing & Spray Areas (Articles 511, 514, 516)
Key Takeaways
Parking garages are unclassified; repair garages are classified by fuel type and ventilation under Tables 511.3(C) and 511.3(D).
Around a motor fuel dispenser, the area within 20 feet horizontally and up to 18 inches above grade is Class I, Division 2 (Table 514.3(B)(1)).
Fuel dispensing emergency disconnects must be located not less than 20 feet nor more than 100 feet from the dispensers they serve (NEC 514.11(A)).
Underground PVC at a fuel island needs 2 feet of cover and threaded metal conduit for the last 2 feet before it emerges (NEC 514.8).
A seal must be the first fitting after a conduit emerges from the earth or concrete into a dispenser (NEC 514.9).
Commercial Garages, Motor Fuel Dispensing & Spray Areas (Articles 511, 514, 516)
Articles 510 through 517 apply the hazardous-location rules of Articles 500–506 to specific occupancies. Each article tells you exactly where the classified areas begin and end, so you don't have to work out the classification yourself. Under 510.2, the general rules of Chapters 1–4 and Articles 500–504 apply except as these articles modify them. In Nebraska, these rules show up in:
- dealership and farm-implement repair shops;
- truck stops and convenience-store fuel islands along I-80;
- cooperative fuel and propane depots; and
- body shops with paint booths.
1. Commercial Garages, Repair and Storage (Article 511)
Parking garages are not classified. Garages used only for parking or storing vehicles are unclassified (511.3(A)).
Repair garages are classified by fuel type and ventilation. The two key definitions are:
- a major repair garage works on engines, fuel systems, or bodies, and may drain fuel; and
- a minor repair garage handles lubrication, inspection, tires, brakes, and similar work without draining fuel tanks.
The classification tables are:
- Table 511.3(C): vehicles using heavier-than-air fuels such as gasoline, diesel, and propane. The hazard collects at the floor and in pits.
- Table 511.3(D): vehicles using lighter-than-air fuels such as natural gas (CNG) and hydrogen. The hazard collects at the ceiling.
| Area (heavier-than-air fuels) | Typical classification |
|---|---|
| Pit, below-grade work area, or subfloor work area, not ventilated, in a major repair garage | Class I, Division 1, entire space |
| The same space in a minor repair garage | Class I, Division 2 |
| Floor-level area up to 18 inches above the floor, where required by the table and not removed by ventilation | Class I, Division 2 |
| Adequately ventilated areas meeting the table's air-change requirements | Reduced or unclassified, per the table |
Read the table for the exact ventilation conditions and distances. They are the most-tested details in Article 511.
Wiring and equipment:
- Above classified areas (511.7): Fixed wiring above a classified location must be in metal raceways, PVC, ENT, MI, MC, or other approved methods.
- Sparking equipment: Equipment less than 12 feet above the floor that may produce arcs or sparks must be totally enclosed or built to prevent the escape of sparks.
- Lighting over lanes: Fixed lighting over lanes where vehicles are commonly driven must be at least 12 feet above the floor unless it is totally enclosed.
- Pendants and cords (511.7): Pendants and cords must be suitable for the location and hung so they do not reach into the classified area unless identified for it.
- Sealing (511.9): Seals follow 501.15. Classified-area boundaries need seals just as in Article 501.
- GFCI: Service bays and similar garage areas are GFCI locations under 210.8(B), which covers 125-volt through 250-volt receptacles on single-phase circuits of 150 volts or less to ground and 50 A or less.
- Battery chargers and their control equipment may not be installed in classified locations.
2. Motor Fuel Dispensing Facilities (Article 514)
Classified areas (Table 514.3(B)(1))
| Location | Classification |
|---|---|
| Inside the dispenser enclosure | Class I, Division 1 |
| Within 20 ft horizontally of the dispenser enclosure, from grade up to 18 inches above grade | Class I, Division 2 |
| Pits, boxes, or spaces below grade, any part of which lies within a Division 1 or 2 area | Class I, Division 1 |
| Underground tank fill openings, vents, and similar points | Classified per the table's radii |
Underground wiring (514.8)
- Underground wiring must be in threaded RMC or threaded steel IMC.
- PVC or RTRC is permitted where buried under at least 2 feet of cover. The last 2 feet of the run to the point of emergence, or to the connection with an aboveground raceway, must be threaded RMC or threaded steel IMC, and an EGC must be included.
- Any portion of wiring below the surface of a Division 1 or 2 area must be sealed within 10 feet of the point of emergence above grade.
Sealing (514.9)
A seal is required in each conduit run entering or leaving a dispenser, or any cavity or enclosure in direct communication with it. The seal fitting, or a listed explosionproof reducer at the seal, must be the first fitting after the conduit emerges from the earth or concrete.
Emergency electrical disconnects (514.11(A))
Fuel dispensing systems need one or more clearly identified emergency shutoff devices or electrical disconnects:
- installed in approved locations not less than 20 feet nor more than 100 feet from the dispensers they serve;
- disconnecting power to all dispensing devices, all remote pumps, all associated power, control, and signal circuits, and all other electrical equipment in the classified areas around the dispensers; and
- requiring manual reset after operation, in a manner approved by the authority having jurisdiction.
At attended self-service stations, the devices must be readily accessible to the attendant. At unattended self-service stations, additional emergency controls are required at each group of dispensers or at the outdoor equipment that controls them.
Maintenance disconnect (514.13)
Each dispensing device must have a means to remove all external voltage sources during maintenance and service, including power, communications, data, and video circuits, and including feedback. The means may be located away from the dispenser, but it must be capable of being locked in the open position (110.25).
3. Spray Application, Dipping, Coating & Printing (Article 516)
Body-shop paint booths and industrial finishing rooms fall under Article 516.
- Inside spray booths, spray rooms, and exhaust ducts: Classified Division 1 (or Zone 1 for vapors and Zone 21 for powders).
- Areas around booth openings: Division 2 (or Zone 2) to the distances shown in the article's figures.
- Lighting: Booth lighting is commonly installed outside the booth, shining through sealed, noncombustible panels so lamps are outside the classified space.
- Interlocks: NFPA 33, the spray-application standard that Article 516 works with, requires spray equipment to be interlocked with the booth's exhaust ventilation, so spraying cannot occur unless the fans are running.
- Electrostatic equipment: Electrostatic spraying and detearing equipment has its own rules for grounding of objects being coated and for spacing.
- Equipment next to booths: Electrical equipment above or next to a spray area that is not separated by a tight partition must not be able to release sparks or hot metal particles. It must be totally enclosed or constructed to prevent their escape.
4. Applying Articles 500–504 Inside These Spaces
Once a space is classified, the Article 501 (Class I) rules apply, as covered in section 7.1:
- threaded RMC or IMC in Division 1;
- explosionproof enclosures with five full threads engaged;
- seals within 18 inches of arcing enclosures; and
- boundary seals within 10 feet.
The occupancy articles change only where the boundaries are and add occupancy-specific rules such as the 514.11 emergency disconnect.
5. Common Exam Traps
- Dispenser Division 2 radius: The Division 2 area is 20 feet horizontally and 18 inches high. It is not 20 feet high.
- Emergency disconnect distance: The device must be at least 20 feet and no more than 100 feet from the dispensers.
- Maintenance disconnect: It must remove all external voltage sources, including data and communications circuits and feedback, and it must be lockable.
- Underground PVC at a fuel island: PVC needs 2 feet of cover, plus 2 feet of threaded metal conduit before emergence.
- Parking garages: They are unclassified. Only repair garages are classified.
Under NEC Table 514.3(B)(1), how is the area around an outdoor gasoline dispenser classified at grade level?
Class II, Division 2 within 10 feet of the dispenser island
Class I, Division 1 within 50 feet of the dispenser in every direction
Class I, Division 2 within 20 feet horizontally, up to 18 inches above grade
Unclassified everywhere outside the dispenser's own metal enclosure
Under NEC 514.11(A), where must the emergency electrical disconnects for fuel dispensers be located?
More than 100 feet from the dispensers, to stay outside the classified area
Within 10 feet of each dispenser
Not less than 20 feet nor more than 100 feet from the dispensers they serve
Inside the store, at the main service panel only
In a major repair garage working on gasoline vehicles, how does Table 511.3(C) classify the entire space within an unventilated service pit?
Unclassified
Class I, Division 1
Class II, Division 1
Class I, Division 2
Sections you finish are checked off in the contents.