Topics discussed in our “Code Forum” column involve complicated issues requiring extensive analysis. However, not every Code question warrants such in-depth treatment. Here are the latest short answers to questions posed on our Web site. Coverage includes topics in: Sec. 110-22, 514-5, GFCI breakers and Sec. 305-6(a), and the extent of hazardous (classified) locations in sewerage pump stations.
Q. Sec. 514-5(c) covers special disconnecting requirements for unattended self-serve gas stations. Where must I locate the additional emergency disconnects? If I have three separate islands, must each have an emergency disconnect? Is this in addition to the disconnect mentioned in Sec. 514-5(a)—the one having to be no less than 20 ft and no more than 100 ft away? Must they be across-the-line devices?
A. You need to track two disconnecting methods in this section. First, Sec. 514-5(a) requires a disconnecting means that simultaneously opens every pole (including the grounded conductor if any) of a circuit run to a fuel dispenser. The 1993 NEC broadened this requirement. Now, you have to include “dispensing equipment, including equipment for remote pumping systems.”
You’ll often find dispensing pumps remotely located from the actual fuel dispenser. Note: This rule applies to at least one disconnect in the circuit (location not specified), not every disconnect. However, in the case of a self-service station, be sure the emergency disconnects specified in Sec. 514-5(b) and -5(c) meet this requirement.
For attended stations [covered in Sec. 514-5(b)], you also have to set a Sec. 514-5(a)-compliant disconnecting means within 100 ft of the dispensers, in a location acceptable to the inspector. As the reader noted, more stringent rules apply to unattended self service stations.
Unattended stations, covered in Sec. 514-5(c), also include a minimum distance to the emergency switch of 20 ft. In addition to the disconnect requirement, be sure there are additional emergency controls on each group of dispensers or on the outdoor equipment used to control the dispensers. This means at each island. These controls must shut off all power to all dispensing equipment at the station. You also have to arrange these controls so they manually reset only in a manner approved by the inspector.
Although the main emergency disconnects must be across-the-line devices that qualify under Sec. 514-5(a) [notice Sec. 4-1.2 in NFPA 30A uses the phrase “easily accessible switch(es) or circuit breaker(s)”], the literal text allows remote control devices for the additional controls that are restricted in their ability to be manually reset.
Q. I’ve always treated sewer lift-station wet-wells as hazardous locations, and wired them in compliance with Chapter 5 of the NEC. However, maintenance personnel complained about the sealing fittings when pumps or floats required removal. After pump change-outs, they wouldn’t bother with sealing the fittings again. I couldn’t find justification for classifying the wet-wells as hazardous locations. Are sewer lift-station wet-wells classified locations or not?
A. The best answer is sometimes. The NEC doesn’t make this kind of area classification. In this case, consult NFPA 820, Standard for Fire Protection in Wastewater Treatment and Collection Facilities. The NFPA Standards Council is releasing a new edition. It depends on the nature of the waste and whether it is multifamily, etc. For example, Table 2 in that standard specifically declares “pumping units” serving one to five dwelling units to be unclassified. On the other hand, many portions of larger systems carry strong Class I Div. 1 Group D classifications.
Q. I work for a listed shop under the UL industrial controls shop program (that allows us to apply UL labels to the industrial control panels). Recently, we found out we’ll have to mark our control enclosures showing the ampere interrupting current rating (AIC rating) of the equipment per UL 508. Does this follow some specific change in the NEC? How do we make these calculations?
A. The UL requirement probably follows the change in Sec. 110-22 some time ago requiring this information where series combination ratings are relied upon for protection. Industrial control equipment panels usually include overcurrent protective devices. Many times installers connect this equipment and forget it—as if it were a “black box.” It typically contains branch-circuit and feeder devices that are essential elements of a complete electrical circuit. So you must install and inspect it in accordance with NEC rules.