Outdoor Fuel Dispensing

steve66

Senior Member
Location
Illinois
Occupation
Engineer
I have some new outdoor fuel pumps - both diesel and gasoline that are wired back to the building.

I understand I need seal-offs at both ends of the conduits. That is one seal off where the conduit enters the building, and another at the pumps just before the conduit enters the ground.

Can the sealing fittings be non-explosion proof?

I also have a light pole at the pumps that has 2 conduit entries. Since those conduits go underground under the Class 2 area, I believe it also needs seal-offs.

How to get 2 seal-offs to fit in a pole is my second question? I'm not sure if one would even fit.
 

oldsparky52

Senior Member
Do you have a reference? Everything I have seen says explosion proof isn’t required for class I div 2.
I believe the area around the pumps (the 20' radius) is C1D2 underground and any conduit that passes through that area (with a fitting in that area) will require the x-proof seal. My code books are packed away right now so I can't help with a reference, but there used to be a drawing in the 514 section that depicted this (may have been in my handbook, I don't remember).
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Do you have a reference? Everything I have seen says explosion proof isn’t required for class
Again, this is my opinion only. The problem arises because CMP14 and the NEC Technical Correlating Committee (TCC) do not have original content control of Article 514 or any Article from 511 to 516 where the original content is extracted from another external NFPA document. See the Scopes and Title Informational Notes (IN) of the various Articles; in this case, Article 514 Title IN and Section 514.1 IN. Article 514 is extracted from NFPA 30A.

The NFPA 30A Technical Committee (TC) has had a long and confusing history of classifying below-grade locations. As recent as the 2002 NEC, what has become Figure 514.3 in the current edition specifically indicated below grade was Class I, Division 1. The supporting wording in Section 514.3 and parts of Section 514.8 would sometimes declare in various NEC Editions that below grade may not be Division 1, but it was to be treated like it was anyway. This was because spillage could seep below grade and enter the raceway systems.

On the other hand, CMP14 has tried to justify reducing the sealing requirements of the Division 2/Unclassified boundary for some time. I personally disagree with the current philosophy that the boundary seal does not need to be explosionproof if the CMP is concerned about transmitting vapors/gases. Oddly enough, I believe most Division 2/Unclassified boundaries do not need to be sealed at all. However, those that do need to be sealed should be explosionproof. The current CMP14 reasoning is based on a misapplication of the Intrinsically Safe philosophy that doesn't require an explosionproof seal at the boundaries. [See Section 504.70] For intrinsically safe systems, this is reasonable because there the purpose is to minimize transmitting gases/vapors, BUT there is also no source of ignition in the raceway either. However, that is not a proper application at the Division 2/Unclassified boundary because there is a source of ignition in the raceway if there is a concern of gases/vapors in the raceway.

So, IF one believes that fuels can enter the below-grade raceways, THEN where boundary seals are employed, they should be explosionproof.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Again, this is my opinion only. The problem arises because CMP14 and the NEC Technical Correlating Committee (TCC) do not have original content control of Article 514 or any Article from 511 to 516 where the original content is extracted from another external NFPA document. See the Scopes and Title Informational Notes (IN) of the various Articles; in this case, Article 514 Title IN and Section 514.1 IN. Article 514 is extracted from NFPA 30A.

The NFPA 30A Technical Committee (TC) has had a long and confusing history of classifying below-grade locations. As recent as the 2002 NEC, what has become Figure 514.3 in the current edition specifically indicated below grade was Class I, Division 1. The supporting wording in Section 514.3 and parts of Section 514.8 would sometimes declare in various NEC Editions that below grade may not be Division 1, but it was to be treated like it was anyway. This was because spillage could seep below grade and enter the raceway systems.

On the other hand, CMP14 has tried to justify reducing the sealing requirements of the Division 2/Unclassified boundary for some time. I personally disagree with the current philosophy that the boundary seal does not need to be explosionproof if the CMP is concerned about transmitting vapors/gases. Oddly enough, I believe most Division 2/Unclassified boundaries do not need to be sealed at all. However, those that do need to be sealed should be explosionproof. The current CMP14 reasoning is based on a misapplication of the Intrinsically Safe philosophy that doesn't require an explosionproof seal at the boundaries. [See Section 504.70] For intrinsically safe systems, this is reasonable because there the purpose is to minimize transmitting gases/vapors, BUT there is also no source of ignition in the raceway either. However, that is not a proper application at the Division 2/Unclassified boundary because there is a source of ignition in the raceway if there is a concern of gases/vapors in the raceway.

So, IF one believes that fuels can enter the below-grade raceways, THEN where boundary seals are employed, they should be explosionproof.
Excellent info. Thanks.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
I agree 2 will not fit and one needs to be perfectly installed to be accessible.
Wondering if I can have the contractor leave a hole in the top middle of the base for the seal offs?

Also wondering if a seal off is really necessary where a conduit terminates in a light pole? If the intent is to keep vapor from traveling in the conduit on past the foundation of the light (basically keeping vapors from moving toward the light fixture), its kind of pointless since the conduit ends at the pole anyway, and most poles I've seen have a big air space between the pole and the foundation.

In other words, the conduit terminates in open air above the Division 2 area, so what's the point on having a seal off?
 

oldsparky52

Senior Member
Also wondering if a seal off is really necessary where a conduit terminates in a light pole? If the intent is to keep vapor from traveling in the conduit on past the foundation of the light (basically keeping vapors from moving toward the light fixture), its kind of pointless since the conduit ends at the pole anyway, and most poles I've seen have a big air space between the pole and the foundation.

In other words, the conduit terminates in open air above the Division 2 area, so what's the point on having a seal off?
I agree with your logic, but from what I understand the code to say, you must have that sealoff. Now, if you could find a 30' piece of conduit that stubbed up into the light pole (at a height above the classified location) and got out of the 20' radius before the coupling then I think you would have a case to not have the sealoff.

With the new controls on fuel leaks, the chances of product getting into conduits is near zero.
 
Last edited:

oldsparky52

Senior Member
Wondering if I can have the contractor leave a hole in the top middle of the base for the seal offs?
?? Are you talking about a standard 4x4 pole on a concrete base? For some reason I was thinking about a light pole mounted to a footing poured in the fuel island with the bottom of the pole near the elevation of the fuel island.

Any way you can make this conduit a dead end instead of looping? Another solution (although cosmetically it doesn't look good) is to let the conduits stub up/down outside the pole, then LB into the pole?
 

oldsparky52

Senior Member
With the new controls on fuel leaks, the chances of product getting into conduits is near zero.
This reminded me of something. Circa 1973, I was a green helper for an EC that was doing a gas station. He was in partners or friends with the fuel contractor and I got put on calibration of the dispensers. I was told to just pump the gas into the ground under the dispenser until I got the air out of the line and then check calibration in a test can. I just looked at the guy, dumbfounded.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
This reminded me of something. Circa 1973, I was a green helper for an EC that was doing a gas station. He was in partners or friends with the fuel contractor and I got put on calibration of the dispensers. I was told to just pump the gas into the ground under the dispenser until I got the air out of the line and then check calibration in a test can. I just looked at the guy, dumbfounded.
Couldn't do that today for a couple of reasons. The EPA would have a fit, and with the current price of gas, it would be like pumping money into the ground.
 
Top