Class 1 hazardous location

[Deke12754]

I have a diesel fuel tank that needs power ran to it. The fuel tank is above ground and is located on the end of 200'x 80' steel building. The fuel company placed the tank 8'-9' away from the 480 volt 200 amp disconect installed on the building. The conduit system is going to go down the side of the building and underground over to the tank's pump using the appropriate seal offs and the E-stop.
My question is how far away does the edge of the tank need to be from the disconnect? Also how far off the building does the tank need to be?

 

[ryan_618]

Re: Class 1 hazardous location

Diesel fuel is not within the scope of Article 500 or 501. The area you discuss can be wired with romex, and the disconnect placed on the tank.

 

[rcwilson]

Re: Class 1 hazardous location

I agree. Diesel fuel by itself is not a reason to classify an area for electrical purposes. A fire or insurance inspector may want the disconnect or service entrance outside of the diesel fuel containment basin to prevent collateral damage from a large fire, but there is no electrical code requirement. (That?s MHO.)

(Edited for spelling errors.)

[ October 19, 2005, 05:27 PM: Message edited by: rcwilson ]

 

[rbalex]

Re: Class 1 hazardous location

Ryan,

I got "dibs" on this being one of my five NEC questions

I also concur with the above two statements. Diesel storage alone is not the basis for any electrical area classification.

 

[hardworkingstiff]

Re: Class 1 hazardous location

If you are in Pennsylvania, contact your local fire marshal before you commence to work!

They make you install around diesel as if you are in a Flammable liquid location.

 

[john m. caloggero]

Re: Class 1 hazardous location

Article 500, 501 address "flammable liquids". Flammable liquids are liquids that give of vapos below 37.8 degrees C (100 degrees F). Where diesel fuel is handled or transferred into containers in temperatures in excess of 100 degrees F, where vapors might escape, the space would be considered a hazardous (classified) location in the vicinity of the handling of the fuel transfer.

 

[ryan_618]

Re: Class 1 hazardous location

Two things:

1) When does the fuel ever reach 100 degrees? I would think in an underground storage tank, the temperature would be closer to 50. In an aboveground tank, the tank will (probably) be double lines, and the liquid would be closer to room temperature, even in a warm/hot climate.

2) Just out of curioisity...has anyone ever heard of an explosion or accident involving diesel fuel?

 

[dadeo]

Re: Class 1 hazardous location

I know at our plat we burn some really CRUDE oil. Thick stuff so thick it has to be heated don't know the viscosity but i guess its like tar Don't know the temp they heat it at but if you wish i can find this out?

 

[ryan_618]

Re: Class 1 hazardous location

If you don't mind, that would be great. Thanks.

 

[don_resqcapt19]

Re: Class 1 hazardous location

John,
While I agree that the area should be classified based on both the ambient temperature and the flash point of the product, I don't think that idea is supported by the rule in 514.3(A). It says that you only consider the flash point of the product. It does not say that if you are handling a liquid with a flash point of 100?F and with an ambient of over 100?F, that the area must be classified. Probably a good idea, but I don't see where the NEC say that.
Don

 

[john m. caloggero]

Re: Class 1 hazardous location

Gentlemen: The clue to my earlier answer pertaining to Diesel fuel dispensing can be found in Section 500.1, Scope and Section 500.5. It is very clear where it states Articles 500 - 504 cover the requirements in locations where fire or explosion hazards exist due to FLAMMABLE gases or vapors.... 500.5 .....and the likelihood that may be present.... Diesel fuel has a flash point above 100 degrees F. Transfer of fuel in an ambient of 115 degrees causes vapors to be emitted which are flammable. The Code does not say that the material has to be classified, but that it exists as a flammable material.

 

[don_resqcapt19]

Re: Class 1 hazardous location

John,

The Code does not say that the material has to be classified, but that it exists as a flammable material.

Does mean that there is no reason for section 514.3(A)? That section says that for a "Motor Fuel Dispensing Facility", areas handling fuels with a flash point above 100?F "shall not be required to be classified. I don't see where rules in 500 or 501 change this. Again, I think that you should classify if you are handling fuels above their flash point, but I don't see a code rule that says this for a Motor Fuel Dispensing Facility.
Don