Fiber optic cable in Class 1 Division 1 area

[beale]

I am working on a gas station site that has a set of direct buried fiber optic cables running under our fuel dispenser island.

According to the electrician contractor we will be in violation of NEC code once fuel is delivered.

I understand the danger of cooper communication lines that do not have conduit and EY?s at the termination/start points but this fiber line runs through the site and has a heavy plastic insulation.

My question is:

Does this fiber cable put the site in violation of any NEC code once fuel (gasoline & diesel) is delivered?

I appreciate your replies.


Thank you,

Steve

Edited to remove personal Info

[ January 19, 2005, 04:38 PM: Message edited by: rbalex ]

 

[dereckbc]

Re: Fiber optic cable in Class 1 Division 1 area

I think that is a stretch. Possible if the fiber has a metalic stregnth member, shield, or locating wire built into it. Sorry do not know any specific NEC rule.

 

[petersonra]

Re: Fiber optic cable in Class 1 Division 1 area

I ran into this one time. It seems there is some concern that vapors might be transmitted from a hazardous area to a non-hazradous area through the sheath.

I seem to recall that you can get FO cable that is made so vapors cannot be transmitted in this way.

 

[rbalex]

Re: Fiber optic cable in Class 1 Division 1 area

500.8(E) Fiber Optic Cable Assembly. Where a fiber optic cable assembly contains conductors that are capable of carrying current, the fiber optic cable assembly shall be installed in accordance with the requirements of Articles 500, 501, 502, or 503, as applicable.

Above is the "basic" rule. Table 770.53 lists cables suitable for classified locations.

The contractor is probably referring to 514.8; however, there are still too many open questions in your description to give a more definitive response. Ask the contractor what the specific violation is.

 

[beale]

Re: Fiber optic cable in Class 1 Division 1 area

First off thank you for all your replies.

The contractor in question is in a cellular dead area and I can not get a hold of him.

The construction site has 3 direct buried fiber optic cables that are approx ?? thick, they run through the site without ?day lighting? in a trench that is 2.5? deep. All of the FO cables are the same with a 08956M: printed on the insulation.

The cables are approx 2 miles long, one end terminates in a building 1 ? miles from the site and the other end goes into another building for the remaining distance.

The fear is as petersonra pointed out: that somehow the insulation will get compromised and vapor will travel via the sheath into the buildings. It would take some pretty extraordinary events to make this happen though, the insulation on FP cable, as I understand it, is bonded to the insulation so without some kind of driving force or pump this scenario just isn?t possible.

I am not an electrician but I?m sure there must be a governing authority that could lay this issue to bed one way or the other. Do any of you know of such an authority?

Thank you again for your time and advice,

Steve

 

[charlie]

Re: Fiber optic cable in Class 1 Division 1 area

Steve, if he is concerned about fiber optic cable, then why wouldn't he be concerned about the interstices in the power conductors?

 

[rbalex]

Re: Fiber optic cable in Class 1 Division 1 area

Originally posted by charlie:
Steve, if he is concerned about fiber optic cable, then why wouldn't he be concerned about the interstices in the power conductors?

In theory he should be - see my favorite FPN (not) :

501.5...FPN No. 2: Gas or vapor leakage and propagation of flames may occur through the interstices between the strands of standard stranded conductors larger than 2 AWG. Special conductor constructions, for example, compacted strands or sealing of the individual strands, are means of reducing leakage and preventing the propagation of flames.

To address Steve?s question, if the fiber optic cables are indeed 2.5? below grade, they?re a non-issue, they are out of the mandated underground Division 1 location. (See Figure 514.3)

 

[charlie]

Re: Fiber optic cable in Class 1 Division 1 area

To address Steve?s question, if the fiber optic cables are indeed 2.5? below grade, they?re a non-issue, they are out of the mandated underground Division 1 location. (See Figure 514.3)

Bob, how do address the second sentence in 514.8?

 

[rbalex]

Re: Fiber optic cable in Class 1 Division 1 area

Originally posted by charlie:
...Bob, how do [you] address the second sentence in 514.8?

As I said in my first response, it's the Section the contractor is most likely referring to.

Basically it and an analogous Section for bulk storage (515.8) are based on ?spillage? rather then ?leakage.?

?Spillage? is considered incidental and creates ?contaminated? soil; ?leakage? is considered catastrophic and creates ?hazardous? soil.

When contaminated soil is recovered through excavation it is generally treated as a hazardous product; however, under most environmental regulations, unexcavated contaminated soil may be left in place. Hazardous soil, once breached by excavation, must be totally recovered. I?ve seen tank farms where the soil could almost be refined itself from the leakage . Refineries avoid underground work like the plague in those areas. I?ve also seen gasoline-fueling stations where site storage leaks create hazardous soil.

Both ?spillage? and ?leakage? for new installations are tightly controlled by today?s environmental regulations.

I don't hold a "China syndrome" view of 514.8. If we treated them by the strictest definitions those little spills we all have occasionally would be Division 1 [See 500.5(A)(1)(1)], but Figure 514.3 does not indicate that; nor does it indicate that the entire area under the Division 2, location is Division 1 as an absolute reading of 515.8 might suggest. A maximum Division 1 depth of 18? is more than adequate for incidental spills. NOTE: While "pits" and "depressions" below Division 2 areas are commonly classified Division 1, it is NOT a general requirement to classify the underground.

I don?t know what the alphanumeric ?08956M? means. But, unless there are conductors in the assembly, 500.8(E) would indicate there is no requirement beyond Art 770 that applies.

I really didn?t want to write an essay.

 

[charlie]

Re: Fiber optic cable in Class 1 Division 1 area

Bob, you write such good essays.

 

[msd]

Re: Fiber optic cable in Class 1 Division 1 area

from 2005 NEC

514.8 Underground Wiring.
Underground wiring shall be installed in threaded rigid metal conduit or threaded steel intermediate metal conduit. Any portion of electrical wiring that is below the surface of a Class I, Division 1, or a Class I, Division 2, location [as classified in Table 514.3(B)(1) and Table 514.3(B)(2)] shall be sealed within 3.05 m (10 ft) of the point of emergence above grade. Except for listed explosionproof reducers at the conduit seal, there shall be no union, coupling, box, or fitting between the conduit seal and the point of emergence above grade. Refer to Table 300.5.
Exception No. 1: Type MI cable shall be permitted where it is installed in accordance with Article 332.
Exception No. 2: Rigid nonmetallic conduit shall be permitted where buried under not less than 600 mm (2 ft) of cover. Where rigid nonmetallic conduit is used, threaded rigid metal conduit or threaded steel intermediate metal conduit shall be used for the last 600 mm (2 ft) of the underground run to emergence or to the point of connection to the aboveground raceway, and an equipment grounding conductor shall be included to provide electrical continuity of the raceway system and for grounding of non?current-carrying metal parts.

 

[mhulbert]

Re: Fiber optic cable in Class 1 Division 1 area

"I don?t know what the alphanumeric ?08956M? means"


Just a guess, but maybe it's a sequential length marking in meters? ie 8,956 meters... That would be a large spool of cable, but given the range of fiber optics, it's possible.

 

[prewrathrap]

Re: Fiber optic cable in Class 1 Division 1 area

the numbers on the cable may be the type of cable also. Was a manufacturer listed on outside of cable also - if yes call manufacturer and find out what numbers indicate