trying to classify an LP area to determine the boundaries for protection in the NEC. this is waaaaay confusing.
first question is where to measure from. is it anywhere on the length of the tank, all fittings associated with the tank, only the transfer point from the tank to the bottles?
dispenser, dispenser enclosure, dispenser base are all used to define the classified areas in table-514.3(B)(2)..... did i miss the definiton of dispenser somewhere?
then what articles apply to figure the distances for protection from pole lights or canopy fluorescents or parking lot receptacles? from what i read, if they are outside the class I div 1 or 2 areas in the table in 514.3, they are ok.
i eliminate articles 502 for dusts, 503 for class 3 like sawmills and textile mills, 504 I.S. systems, and 505 the IEC zones.
i think 500, 501, and 514 apply.. and NFPA 58 LP Gas Code, but don't have that one.
lots of things apply, but here's my important list, please add to it if something key is missing.
500.7(A) only Explosionproof is used in Class I [not Dust Ignitionproof, or Dusttight] 500.8(A) equipment to be identified 500.8(D) only NPT threading taper 3/4" per foot [hmmmm, not metric!! guess it hasn't been sprinkled by the imperial pixie dust yet] wrenchtight and listed fittings for threaded conduit. 500.9 sends you to 510 thru 517 for specific occupancy types
501.1 Class I applies to propane, gasoline, methane, acetone, hydrogen, etc 501.4 Class I locations use threaded RMC or steel IMC, 5 NPT threads engaged [excp. RNMC ok in concrete], listed 3' flex at motors is ok, 501.4(A)(3) all boxes, fittings, & joints to be approved 501.4(B)(1-3) wiring methods 501.4(B)(4) boxes, fittings, joints ok if not explosionproof at outlets or enclosures w/o arcing 501.5 seals 501.5(A)(4) Class I Div 1 Boundary, conduit leaving sealed w/in 3.05 m [10 ft] of boundary, ok for pipe to pass thru if w/o fittings and 300 mm [12 in] outside boundary 501.5(B)(2) Class I Div 2 Boundary, conduit leaving sealed w/in 3.05 m [10 ft] of boundary, ok for pipe to pass thru if w/o fittings and 300 mm [12 in] outside boundary 501.5(C) Class I Div 1 & 2 501.9(A) Class I Div 1 luminaires (B) Class I Div 2 Luminaires 501.11 Cords 501.12 Plugs & Receptacles 501.13 THWN is typical for exposure to liquids 501.14 Signaling circuits 501.16 Grounding
514.1 LP Table 514.3(B)(2) LP Classified Areas, Class I Div 1 is enclosure & 450 mm [18 in] from dispenser to 1.2 m [4 ft] above dispenser base; and entire pit beneath and w/in 6.0 m [20 ft] horizontally from dispenser if pit isn't mechanically ventilated; Class I Div 2 is 450 mm [18 in] aboveground and w/in 6.0 m [20 ft] horizontally from dispenser enclosure including pits when mechanically ventilated. 514.7 refers to 511.7 for wiring above Class I locations: arcing equipment, switches, motors, but not receptacles or lamps, less than 3.7 m [12 ft] above floor to be totally enclosed or explosionproof; lights to be 3.7 m [12 ft] above floor or totally enclosed or explosionproof.
Cindy: Doesn't the job have plans??? It should be spelled out (specs) on "plans" that should be required to obtain a permit. Here, the standard is a PE/EE, Architect with PE/EE seals on plans to be submitted for Permit Application and Approval. Are you checking the drawings/specs?? The PE/EE probably would give you the reference NEC articles. The AHJ or whoever "signs off" on the plans/permit should have required reference articles. We usually "give" this type of work to a local guy who specializes in gas stations, LPG, and refinery work. He does it day-in and day-out and has the right answers. John
#82131 - 10/18/0211:20 PMRe: LP areas, this'll put you to sleep
In some states, (Like NJ) some of these applications fall under the jurisdiction of the state. The state approves the plans and the local AHJ has to inspect the site. In the 2002 NEC sec. 514 there is some new wording about LP dispensing area's. It use to be called "Gas station" dispensing areas, now it is for all fuels. (LP,Natural Gas, etc.) There is also lots of info in the NFPA about LP gas areas. I don't have the NFPA book in front of me, it is in the office. It is funny, but I had to inspect a 1000 gal, LP dispenser just this week. It is on a farm so that they can fill up propane bottles for gas grills.