NEC 514.11 Circuit Disconnects - Diesel

M

makoester12

Member
Location
Indiana
Occupation
Electrical Engineer
Good Afternoon,
I am working on an application that strictly contains (2) above ground diesel fuel tanks with motor operated pumps mounted on top. The area has been considered unclassified since only diesel (combustible liquid) is in the area and the flash point of particular blend is ~140 degrees F. My question deals with whether the circuit disconnect requirements within 514.11 still apply or not? Essentially, if the area is considered unclassified, can the remainder of Article 514 be ignored? Within the handbook commentary, it is stated that "Article 514 encompasses all locations where volatile flammable liquids or gases are dispensed into the fuel tanks of self-propelled vehicles or other approved fuel tanks." While this is only commentary, does this provide indication of the intent of Article 514? Additionally, 514.11 seems to indicate that the area surrounding the dispenser is deemed classified ("and to all other electrical equipment in the hazardous (classified) locations surrounding the fuel dispensing devices").

Thanks for your input.
 
In my opinion all of the rules in 514 apply except those related to the classified areas, which you do not have.
The handbook commentary does not match up with the scope of the article, and the scope is code, the commentary is not.
 
Don,
Thank you very much for the feedback. It does seem advantageous to have a remote emergency disconnect to shutoff the pumps in the event of a spill or other potential issue.

Would 514.9 apply as well then? Per 514.9, "A listed seal shall be provided in each conduit run entering or leaving a dispenser or any cavities or enclosures in direct communication therewith." While this section does not particularly reference a classified area, it does not seem necessary when the area is unclassified and no conduit runs pass through a classified area.

Thanks again.
 
makoester12 said:
Don,
Thank you very much for the feedback. It does seem advantageous to have a remote emergency disconnect to shutoff the pumps in the event of a spill or other potential issue.

Would 514.9 apply as well then? Per 514.9, "A listed seal shall be provided in each conduit run entering or leaving a dispenser or any cavities or enclosures in direct communication therewith." While this section does not particularly reference a classified area, it does not seem necessary when the area is unclassified and no conduit runs pass through a classified area.

Thanks again.
Click to expand...
Again, while I do see some advantages of the emergency disconnect, I am still trying to understand the main purpose of it from a code perspective. If it is to strictly stop the flow of fuel, it would appear to make sense. However, reading 514.11 as well as NFPA 30A, it appears the main purpose is to remove a potential ignition source. Since this area is not classified, no other circuits at the pumps will require disconnection. Additionally, within 514.11 (which corresponds to NFPA 30A), it states that "Intrinsically safe systems shall not be required to meet this requirement." Wouldn't this only make sense if the area was considered classified?

Again, I really appreciate your feedback.
 
makoester12 said:
Again, while I do see some advantages of the emergency disconnect, I am still trying to understand the main purpose of it from a code perspective. If it is to strictly stop the flow of fuel, it would appear to make sense. However, reading 514.11 as well as NFPA 30A, it appears the main purpose is to remove a potential ignition source. Since this area is not classified, no other circuits at the pumps will require disconnection. Additionally, within 514.11 (which corresponds to NFPA 30A), it states that "Intrinsically safe systems shall not be required to meet this requirement." Wouldn't this only make sense if the area was considered classified?

Again, I really appreciate your feedback.
Click to expand...
Since the normal activation of the emergency shutdown is after the ignition, spill, or leak has already happened, it is my opinion that the main reason is to stop the flow of fuel. In the case of a leak or spill, the emergency shutdown will also remove any electrical ignition sources that are related to the dispensing system. If there has already been an ignition, the removal of electrical ignition sources in the area of the dispensing equipment does not change anything. Note that the vehicles in the area are also potential ignition sources.

In the NEC this disconnect has the additional purpose of removing all power to prevent any ignition when the system is being worked on. That is why the NEC requires the disconnect to also disconnect the grounded conductor and NFPA 30A does not require the grounded conductor to be disconnected.

However, the only real answer would be from your Authority Having Jurisdiction. In my area that would be the State Fire Marshal's office.
 
Thanks for your feedback Don. Are you under the assumption that the 514.9 sealing requirements do not apply to unclassified areas?
 
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