Gas Meter A Hazardous Location

[Francis Vineyard]

An engineer from the city’s natural gas supplier who contends that the electrical inspector has the authority enforce their clearance distance of the main disconnect from the outdoor gas meter regulator under article 500; class 1, division 1 hazard. Begin with the IRC scoping “Electrical systems, equipment or components not specifically covered in the chapter shall comply with the applicable provisions of the NFPA 70."



Your thoughts and has anyone heard of applying this to residential gas meters?



500.5 Classifications of Locations.

(A) Classifications of Locations. Locations shall be classified depending on the properties of the flammable gas, flammable liquid-produced vapor, combustible-liquid produced vapors, combustible dusts, or fibers/flyings that may be present, and the likelihood that a flammable or combustible concentration or quantity is present. Where pyrophoric materials are the only materials used or handled, these locations shall not be classified. Each room, section, or area shall be considered individually in determining its classification.

Informational Note: Through the exercise of ingenuity in the layout of electrical installations for hazardous (classified) locations, it is frequently possible to locate much of the equipment in a reduced level of classification or in an unclassified location and, thus, to reduce the amount of special equipment required.

Rooms and areas containing ammonia refrigeration systems that are equipped with adequate mechanical ventilation may be classified as “unclassified” locations.

The NEC does not classify specific Class I, II, and III locations. NFPA technical committees and the American Petroleum Institute (API), among other organizations with experience and expertise in working with flammable liquids, gases, vapors, dusts, fibers and flyings inherent to a process or present under abnormal conditions of operation, determine the parameters, distances, and degrees of hazard associated with classified locations. Some of this information has been extracted from other NFPA and API documents and is included in Articles 511through 517 of the Code.

In some facilities, an expert or team of experts, which may include a process engineer, a mechanical engineer, a safety engineer, and operations personnel, will use the information developed in those NFPA standards and apply it to their specific equipment and process and, depending on the materials and physical equipment and locations (for example, possible leaks at flanges, machinery seals), decide on the area classification, and produce the hazardous area diagram. See the commentary for 500.4(A). Common sense and good judgment must prevail in classifying an area that is likely to become hazardous and in determining those portions of the premises to be classified Division 1 or Division 2.



Francis

 

[Francis Vineyard]

I know this horse will continue to be beaten to death. The situation is there are hundreds if not thousands in our area that are existing where the gas regulator and electrical meter and disconnect are in violation with each other. State law allows replacement of disconnect to be not less safe; however the gas supplier has at its own discretion to shut off the gas until correction. Yet they could just as easily connect piping to vent regulator further away.

A reading of NFPA 497 did not help in clarification; but the 3 ft. distance from the regulator must be documented as a hazardous location.

Tip; don't send pictures of these violations to the gas supplier!

Francis

 

[raider1]

As a utility they have the power to enforce their own requirements.

As far as classifying the area around a gas meter as a Class 1 Division 1 location I would have a hard time justifying that that area would have ignitable concentrations of flammable gases during normal operating conditions.

To classify an area there needs to be engineering documentation for the classification. It is not as simple as stating the area within 3 feet of the gas meter is a class 1 division 1 location. There needs to be demarcation between the division 1 location and the division 2 location and unclassified locations.

I would not go down this road to satisfy the local gas company.

As an electrical inspector I would mention that there is a gas company requirement that the electrical service be located at least 3 feet from the gas meter and leave it at that.

Chris

 

[Francis Vineyard]

Chris thanks for your response.

Update: What could have happened was to place the outdoor Main disconnect to the side of the meter base instead of below within the 3 ft. zone of the public utility gas meter vent.

What did happen is the electrician’s greed will now cost the home owner to relocate the gas meter.

The utility representative and I agreed that the 3 ft. zone is an unclassified hazard and would be impossible to keep all sources of ignition away in an outdoor environment.

Francis

 

[Amish Electrici]

Bear with me, as I try to do some new computer magic:

OOPS. Didn't work. We'll have to do it the hard way. Please open this link, and scroll to page 7:

https://www.nvenergy.com/business/newconstruction/newconstructionN/standards/electric_standards/images/SECTION_7/OS0001U.pdf

Now, that's part of the standards from Reno, Nv., where the same utility provides both electric and gas. I just use them as an example; I have seen several other utilities with similar requirements.

The standards do change over time; I've seen Reno standards where the utility encourged you to have the electric meters grouped right over the gas meters. Now, they don't even want conduit within a foot of the regulator vent.

Notice how the 36" distance is measured; a direct line, at any angle, from the regulator vent to any contact, or orther source of a spark. That's a bit differernt from the way electricians usually measure things, and the net effect is that you can get stuff closer than you might think.

The engineer is a bit shaky in his citation, but as an AHJ the utility most certainly can set their own standard.

I'd wager that the sparky would be held responsible for relocating whatever was needed to make his work comply with the rules- if the issue ever came before a judge. He's the pro, and supposed to know these other standards.

 

[Daddy-0-]

I'm with you Francis... Pipe the vent outlet away from the ignition source and for $10 worth of pipe you are done. Bottom line is that the gas company is not required to hook up the service. they cannot make you enforce it either. We only inspect gas installations after the meter. That meter itself is the gas companies baby.