Paul Estes

[Paul Estes]

I attended Mr. Holt's Florida EC licensing program circa 1983. Am and have been registered PE since, State EC license 614, inactive since 1986.
Situation- Landfill has Methane recovery serving 2- 500KW M/G sets, secondary voltage 4160. Oil pump failed, causing total burnout. Replacement is under way. All wiring within covered steel building is Nema 1, combination of RGC and EMT, some PVC, all Nema 1 devices.
Reading NEC 500, it identifies Methane as Class I Div II Group D. I don't see this as a hazardous area, but can't find a way to substantiate it. 500/501/502 don't leave any 'outs' for airflow, ventilation, or exposure.
Methane is .6 specific gravity, so putting outlets low is a good thing, but do they need to be installed and wired to Class I standards? Also, lighting within that cavity needs to be replaced, Existing facility has been operating since 1996 with no electrical issues.
Your thoughts, please. Giles Electric is my client in this case.
Thanks,
Paul Estes, P.E.

 

[CWillcox]

Nfpa 497?

Nfpa 497?

Maybe the referanced NFPA document will help. This is for chemical processing add you are processing Methane so could apply.

 

[kameele]

Since this is an existing plant, there should have been a hazardous area classification done prior to the original installation (in an ideal world, of course :roll there is some likelihood that the generator room is not classified and therefore the wiring methods would be allowed. It would certainly make sense that whoever laid out the plant would try to avoid putting it in a classified area.

Until the hazardous area classification is done by a qualified person, anything we might say would be guesswork. If there's any more information you can offer, I'd be happy to add as much more as I can.

ETA: BTW, Welcome to the forum. I still a newbie here, but it's a great place to get answers and increase your knowledge.

 

[nakulak]

the NEC provides guidelines, but is a poor substitute for proper engineering. who is the ahj (state DOT ?). you might contact them and ask them for their drawings showing the locations of the classified areas, and you might also consider writing them to CYA ?

 

[rbalex]

Until 2005, this would have been a fairly straightforward question.

Before 2005, NFPA 850,Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations cited NFPA 37, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines, which said (and still says):

4.5.2 Engine rooms or other locations shall not be classified as hazardous locations as defined in Article 500 of NFPA 70, National Electrical Code, solely by reason of the engine fuel, lubricating oil, orhydraulic fluid.

Since 2005, NFPA 850, Section 8.5.1 still cites NFPA 37 but now adds the proviso, “… except as modified by Section 8.5.” Section 8.5 is now greatly expanded over analogous Sections in previous editions with respect to potential fire hazards; however, it still doesn’t actually mandate electrical area classification.

In my opinion, the key is how the fuel is delivered. Several factors such as pressure, flow-rate, ventilation, location of valves and flanges, etc., need to be considered. That is when you need to consult NFPA 497 especially Section 5.4.3; but the whole document is relevant. In addition, your outdoor facilities may need review, especially any gas compressors.

The truth is, in Division 2 the odds are in your favor with most otherwise properly installed wiring methods; but if you ever do have a problem, it will be a big one.

My preferred counsel is the insurer. In any case DOCUMENT it [500.4(A)]