Fuel Dispenser Questions

[Jon456]

There is an existing fuel dispenser (dual pump: gasoline & diesel). It's an older installation so I don't know what code requirements were in effect at the time, but I can't imagine it was ever in full compliance. For example, there is no emergency electrical disconnect for all current-carrying conductors to the dispenser; just an unlabeled standard SPST light switch on the hot conductor in the adjacent unattended office (and you have to walk around the back of the dispenser to get to that office).

The fueling station is going to be upgraded to allow automated payments by the addition of some sensors in the dispenser and a processing terminal in the office. So I wanted to address some of the safety and code issues. But there are challenges to this particular installation:

1. NEC requires an emergency disconnect greater than 20', but no more than 30' (for unattended dispensers). The problem is that there is no place to mount a switch to comply with that requirement. There are two large steel buildings that are about 6' apart and the dispenser sits about 2' out from the face of these buildings, centered on the space between the buildings. There is about 4' from each back corner of the dispenser to the closest point on the facing buildings. Looking at the front of the dispenser, the building on the left has a full-width door, so no front wall to mount an emergency shut-off switch. The building on the right has some front wall space between the corner and the building's main rolling door, but that wall space is not wide enough to mount the switch 20' from the dispenser. The fueling station office is a small 5'x10' room in the corner of this building, with its own man door in the side of the building behind the dispenser. It makes no sense to put the emergency switch in the office (or on that side of the building) because if there were a fuel leak or fire at the dispenser, that would block access to the office. The only solution I can think of is to mount the switch on the outer front wall as far from the dispenser as possible (right next to the rolling main door) and call it good, even though it will be only about 8' (lateral distance) from the dispenser.

2. The entire fueling office space, including the man door into office, is within 20' of the dispenser. In addition to the man door penetrating the outer wall, there is also a 6" square hole cut into the outer steel sheathing of the fueling office for an air inflation hose to pass through; this hole is within 20' of the dispenser and less than 18" above the ground. Therefore, I believe the interior of the fueling office is part of the classified hazardous space up to 18" off the floor. Am I correct? This may present a problem for the installation of the payment terminal, which is pedestal-mounted (and houses electronics & electrical connections within the pedestal).

3. If the office is considered classified, as discussed in the point above, what are the requirements for the office overhead lighting, electrical receptacles, etc.

4. If the emergency shut-off switch disconnects all power conductors to both the dispenser AND the payment processing terminal, then is there a requirement to also disconnect the low-voltage data cables between the dispenser and the payment terminal (recognizing that the data cables will have no power if both the dispenser and terminal are de-energized)?

5. The conduit that brings power to the dispenser has no seal-offs. The conduit originates at an LB on the side of the steel building (inside the building, mating to the LB, is a standard junction box); the LB is about 10' above grade. From the LB, the conduit runs vertically down the side of the building, travels along the ground (parallel to the fuel supply plumbing), enters the containment pan under the dispenser, and then mates to an explosion-proof box within the dispenser. The vertical run of conduit on the side of the building is about 15' from the dispenser. How many seal-offs are required and where should they be located?

 

[rbalex]

I suspect your introductory statement is correct; the remote disconnecting means requirements of Art 514 have been around a long time.

1. In an unattended situation, the remote disconnect means shouldn?t be in an unattended office or any inaccessible location anyway. Unfortunately, ?calling it good? will be an unlikely call from an AHJ?s point of view. You may need to install a compliant remote pedestal location.
2. As I understand your description, unless it is properly ventilated per NFPA 496, you?re correct about the office area up to 18? above the floor being Division 2.
3. Equipment in the classified location must be installed per Article 501.[Sec 514.4] See Sections 514.7 & 8 for other applications.
4. Possibly, read 514.11(A) as it applies to you situation.
5. Several -without knowing the exact dimensions. As I understand your description, there is no underground raceway. As an absolute minimum, there should be a seal for the ??explosion-proof box within the dispenser.? Boundary seals will be dependent on the location of couplings, both in and outside the classifed location.

 

[Jon456]

In an unattended situation, the remote disconnect means shouldn?t be in an unattended office or any inaccessible location anyway.

I should have stated that the unattended "office" is not kept locked, so the switch was readily accessible. The problems with it are:
It is just a standard (and unlabeled) light switch on the hot line (not a true emergency disconnect of both the hot and neutral).
To get to this office, one must go around the dispenser, walking between the dispenser and the corner of the steel building (about a 4' space). Not something you would want to do if there was a fuel leak or fire at the dispenser.

Unfortunately, ?calling it good? will be an unlikely call from an AHJ?s point of view. You may need to install a compliant remote pedestal location.

I realize that and I really wasn't trying to be flippant. I am a stickler for details and like to do things right, including complying with all codes. The problem is that there really is no other place to put a disconnect, even on a pedestal. It can't be out in front of the dispenser (that would put it in the middle of traffic) and it can't be to either side of the dispenser as that would place it in front of the doors of the buildings, thus blocking vehicles from entering/exiting the buildings.

My understanding is that if the office were attended, then having the disconnect within 20' of the dispenser would be compliant. So for our situation, the issue boils down to the difference between "attended" and "unattended". This dispenser is not open to the general public: it is restricted to the operators of the vehicles on the property. Thus each user of the pump could be considered an "attendant". This may be stretching the "letter of the law" so to speak, but I think having a true emergency disconnect mounted on the front of the building, 8' to the side of the dispenser, is a significant improvement over the current set-up (which has been in operation for decades -- and somehow managed to pass numerous inspections during that time).

Equipment in the classified location must be installed per Article 501.[Sec 514.4] See Sections 514.7 & 8 for other applications.

If I understand you correctly, I only have to worry about equipment WITHIN the classified location (i.e., within the 18" area above the ground). Is that what you meant? So does that mean I don't have to worry about the office ceiling light that is suspended over the hazardous location, or the power recepticles that are mounted higher than 18" above the ground?

 

[rbalex]

It sounds like no amount of reinstallation will make this fully compliant. Your best approach is seeking a Section 90.4 ?equivalent objectives? waiver assuming the AHJ accepts training the users as a reasonable alternate in an industrial environment. Inside the office would probably be a better choice. Only 8? away is problematic.

Section 514.4 references 511.7. The receptacles, lights and possibly the wiring above the floor could be a problem. Depending on undisclosed descriptions, the receptacles probably won?t need to be explosionproof, but may need a boundary seal. The lights will need a globe and guard as a minimum. Check 511.7(A) for acceptable wiring. Read all of 511.7 foe application.

 

[Jon456]

Thanks Robert for your advice. Just to be clear, locating the emergency shutoff inside the office would place it only about 10 feet away, plus you have the additional problem of having to walk around the dispenser (in very close proximity) to get to that office -- and to exit/escape the office, as there is no other access to the office except by going between the dispenser and the building. I still think mounting it "in the open" on the front of the building is a better option: at least there would be no risk of getting trapped there.

Regarding the classification of the office as a hazardous location, I've been thinking more about this problem. How do gas stations with attendant booths and convenience stores constructed between the pumps get around this requirement? Those little buildings are well within 20' of the dispensers (typically, there is a line of pumps ahead of and behind the attendent booth/store). I seriously doubt that every electrical circuit, light fixture, and appliance (including coffee makers, microwaves, refrigerators, etc) meet explosion-proof criteria. So is it considered not a hazardous location because the door is normally closed and excludes the possibility of explosive fumes from accumulating?

 

[rbalex]

I looked at inside the office as giving more shelter, if necessary. In the open, is your call if you can sell it to the AHJ.

Every installation has a unique geometry, ventilation plays a part. So does the location of the doors and other openings relative to the classified area. Done properly, they may not have gotten away with anything. I'd have to see or at least understand each specific installation to render an opinion on their compliance.

 

[rbalex]

BTW

BTW

The disconnect may be up 100' (30m) away.

 

[hbiss]

I'm just reading this and wondering what other requirements come into play besides the NEC and NFPA. Normally, fuel dispensing installations are not "forever" and depending on the size of the tanks environmental laws require periodic testing and replacement of the tanks and equipment. Since you say that this is an old installation that was never in compliance a visit from the AHJ may trigger replacement in which case your job will be straight forward.

-Hal