Understanding Requirements for Commercial Garages and Fuel-Dispensing Facilities

Areas adjacent to classified locations aren’t classified if mechanically ventilated at a rate of four or more air changes per hour or when walls or partitions effectively cut off the adjacent area [511.3(E)].

WIRING AND EQUIPMENT

Wiring and equipment within a Class I location must be installed per Art. 501 [Sec. 511.4(A) and (B)]. Fuel‑dispensing units within buildings must comply with Art. 514 [Sec. 511.4(B)(1)].

The lamp and flexible cord of portable lighting equipment must be supported or arranged in such a manner that it can’t be used in a hazardous (classified) location [Sec. 511.4(B)(2)], or it must be identified for a Class I, Division 1 location [Sec. 501.130(B)].

Fixed wiring above a Class I hazardous (classified) location must be in raceways, unless it is one of the following [Sec. 511.7(A)(1)]:

• Type AC, MC, or MI cable.

• Part of a manufactured wiring systems.

• PLTC cable per Art. 725.

Pendant cords above a Class I hazardous (classified) location must be suitable for the type of service and listed for hard usage per Table 400.4 [Sec. 511.7(A)(2)].

Equipment with make‑and‑break contacts installed less than 12 ft above the floor level (excluding receptacles, lamps, and lampholders) must be of the totally enclosed type or constructed to prevent sparks or hot metal particles from escaping [Sec. 511.7(B)(1)(a)].

Lampholders and lamps for fixed lighting over travel lanes or where exposed to physical damage must be at least 12 ft above floor level, unless the luminaires are of the totally enclosed type or constructed to prevent sparks or hot metal particles from escaping [Sec. 511.7(B)(1)(b)].

Underground wiring below a commercial garage must be installed in threaded rigid metal conduit (RMC) or intermediate metal conduit (IMC). Exception: PVC, Type RTRC conduit, and Type HDPE conduit can be installed below a commercial garage if buried under at least 2 ft of cover. Threaded RMC or threaded IMC must be used for the last 2 ft of the underground run. An equipment grounding conductor (EGC) per Art. 250 is required within the raceway [Sec. 511.8].

Raceway, cable, and boundary seals must be installed per Sec. 501.15, and applied to both horizontal and vertical boundaries of the defined Class I locations [Sec. 511.9]. If the Class I, Division 1 boundary is beneath the ground, then the sealing fitting can be installed after the raceway leaves the ground. However, there must not be any unions, couplings, boxes, or fittings (except explosionproof reducing bushings) between the seal fitting and the point where the raceway leaves the earth’s surface [Sec. 501.15(A)(4), Exception No. 2].

FUEL-DISPENSING FACILITIES

The portion of a facility where fuel is stored and dispensed into the fuel tanks of motor vehicles and marine craft, or into approved containers, must comply with Art. 514 (Fig. 2).

What’s most striking about Art. 514 is the large table that makes up about half of it. This table doesn’t provide any electrical requirements, list any electrical specifications, or address any electrical equipment. What this table tells you is how to classify a motor fuel-dispensing area based on the equipment contained therein.

CLASSIFICATION OF LOCATIONS

Figure 514.3 in the NEC shows an example of a typical Class I, Division 1 and 2 location. These areas and dimensions are described in greater detail in Table 514.3(B)(1). If the authority having jurisdiction (AHJ) is satisfied that flammable liquids having a flash point below 100˚F [Art. 100 Volatile Flammable Liquid] won’t be handled, such locations can be unclassified [Sec. 514.3(A)].

Table 514.3(B)(1) is to be used to classify motor fuel-dispensing facilities and commercial garages as defined in Sec. 511.2 where a flammable liquid having a flash point below 100˚F is stored, handled, or dispensed. A Class I location doesn’t extend beyond an unpierced wall, roof, or other solid barrier [Sec. 514.3(B)].

MARINAS AND BOATYARDS

Electrical wiring and equipment serving fuel-dispensing locations in marinas and boatyards must be installed on the side of the wharf, pier, or dock opposite from the fuel piping system [Sec. 514.3(C)(1)]. Is the construction of piers, wharfs, or docks open? If so, then the area 18 in. above the surface of the dock, pier, or wharf and extending 20 ft horizontally in all directions from the outside edge of the dispenser and down to the water level is considered a Class I, Division 2 location [Sec. 514.3(E)(1)].

Electrical equipment and wiring within a Class I location, as defined in Table 514.3(B)(1), must comply with Art. 501. This means you must use threaded RMC and/or threaded IMC for fixed wiring. However, PVC conduit is permitted underground per Sec. 514.8 [Sec. 514.4]. Wiring above a Class I location, as defined in Table 514.3(B)(1), must be installed within a raceway, or in Type AC, MC, MI, PLTC, or TC cable [Sec. 511.7(A)(1)].  

Fixed lighting over travel lanes, or if exposed to physical damage, must be at least 12 ft above floor level, unless the luminaire is of the totally enclosed type or constructed to prevent sparks or hot metal particles from escaping [Sec. 511.7(B)].

Underground wiring beneath a classified location must be installed in threaded RMC or threaded IMC. Electrical conduits located below the surface of a Class I, Division 1 or 2 location, as identified in Table 514.3(B)(1) and Table 514.3(B)(2), must be sealed within 10 ft of the point of emergence above grade [Sec. 514.8] (Fig. 3).

Except for listed explosionproof reducers at the raceway seal fitting, there must be no union, coupling, box, or fitting between the raceway seal fitting and the point of emergence above grade. Exception No. 2: PVC, Type RTRC conduit, and Type HDPE conduit can be installed below a classified location if buried under at least 2 ft of cover. Threaded RMC or threaded IMC must be used for the last 2 ft of the underground run. An EGC per Art. 250 is required within the raceway.

RACEWAY SEAL

A listed raceway seal must be installed in each raceway that enters or leaves a dispenser. The raceway seal fitting or listed explosionproof reducer at the seal must be the first fitting after the raceway emerges from the earth’s surface or concrete [Sec. 514.9(A)].

A raceway seal fitting that complies with Sec. 501.15 must be installed in each raceway run that leaves a Class I location and applies to both horizontal and vertical boundaries of the defined Class I location [Sec. 514.9(B)].

If the boundary is beneath the ground, the sealing fitting can be installed after the raceway leaves the ground, but there must be no union, coupling, box, or fitting, other than listed explosionproof reducers at the sealing fitting in the raceway between the sealing fitting and the point at which the raceway leaves the earth’s surface [Sec. 501.15(A)(4), Exception No. 2].

DISCONNECTS

These four requirements are new with the 2017 NEC:

1. Fuel-dispensing systems must have clearly identified emergency shutoff devices or disconnects installed at approved locations at least 20 ft and not more than 100 ft from the fuel dispensing devices they serve [Sec. 514.11(A)].

2. Emergency shutoff devices or disconnects must disconnect power to all dispensing devices; to all remote pumps serving the dispensing devices; to all associated power, control, and signal circuits; and to all other electrical equipment in the hazardous (classified) locations surrounding the fuel dispensing devices [Sec. 514.11(A)].

3. Attended self‑service stations must have an emergency dispenser disconnect that’s readily accessible to the attendant [Sec. 514.11(B)].

4. At unattended motor fuel-dispensing facilities, the disconnects must be readily accessible to patrons and at least one additional disconnect must be readily accessible to each group of dispensing devices on an individual island [Sec. 514.11(C)].

DISPENSING WITH CODE VIOLATIONS

How can you prevent Code violations when the rules for fuels seem so complex? The core strategy of Art. 511 and Art. 514 is to keep fuel and ignition sources apart from each other. In your design review, identify the ignition sources, and see what these Articles say about isolating them from the fuel.