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Separation distance between HV switches and fuel ports

Separation distance between HV switches and fuel ports

Separation distance between HV switches and fuel ports

(OP)
Hi, I like to find out where I can nail down in the code if there is any separation clearance between HV switches (disconnect switches) and enclosure access of generators, power distribution units, and most importantly, the minimum requried separation distance from the fuel port (to the generators).  I am not too familiar with NESC (for high voltage), but I will do more research there.)  All these units are outdoor, and becasue they are co-located in such tight enivronment, the clearance issue was one of those that came to mind.  For example, I have physically measured, the distance between the 5KV switch and the generator fuiel port is only 27cm (or about 10 in).  I could even open the door fully (> 90deg swing) in 5kV switch compartment, much less than to think about why on earth would someone put them so close together.  If anyone know where to reference the code, I would like to take a look.

RE: Separation distance between HV switches and fuel ports

If you are in the U.S., this is typically controlled by the National Electrical Code. Review the articles on hazardous locations. Also, be sure to review applicable local building codes. Many cities and states have amendments and other codes which may be more restrictive.

The NEC articles on hazardous locations are among the most complex sections of the code. I would strongly advise hiring a consultant experienced in these areas.

RE: Separation distance between HV switches and fuel ports

(OP)
Hi Alehman,

Thanks for your advice.  I have checked that a 30-ft minimum distance is required as open clear zone.  Obviously in the situation I have described, the HV switch (5kV generator disconnect switch) does not have intrinisically safe device to protect against potnetial iginition.  That's what I was woriied about.

 

RE: Separation distance between HV switches and fuel ports

Yes, it won't be intrinsically safe. I think the more applicable term you might be wanting there is classified. If installed within an area that is classified as hazardous, the equipment must be rated with the appropriate classification. Class 1, Division 1 and Class 1, Division 2 are the ratings that would apply to areas with flammable vapors. I don't know of any manufacturer that makes classified medium voltage switchgear.

In many jurisdictions, storage and on-site use of light fuel oil (#1 or #2 diesel) does not require classified equipment, unless it is in a recessed area or pit. The situation is very different for gasoline due to its much lower flash point temperature.

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