Fiber optic cable requirement for CID1 hazardous area.

Srknet

Member
Location
NY
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R&D engineer
Hello,
I am very new to NEC Hazloc installation and certification standard here so I need some expert advise. I am working on a project developing CID1 instrument for the process which includes the fiber optic cable probe and an instrument which would be an explosion proof enclosure with components inside and UL will certify the whole instrument but we are not sure to include the fiber optic probe or not ? since the fiber optic cable will run between the instrument and process pipe and it is only carrying light both ways(sending and receiving) and no electrical conductor at all so I want to learn what are the acceptable methods of protection for such a fiber optic probe that allows us safe installation in hazardous CID1 area and if we go for certifying the fiber optic probe for CID1 then what standard would it will have ? thanks in advance for any suggestion or help.
 

rbalex

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Location
Mission Viejo, CA
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Professional Electrical Engineer
Field wiring for optical fiber installations in Class I, Division 1 are covered in Section 501.10(A)(1)(e) and its cross-references. Section 501.10(A)(1)(e) also describes the cable Types permitted and potential sealing issues. For your application, see Section 501.17 as well. The rest of the installation must be compliant with Article 770 as applicable. In the potential case that grounding/bonding is required see Section 501.30.

Edited to correct reference to Section 501.30
 
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Srknet

Member
Location
NY
Occupation
R&D engineer
hi Bob,
thanks for the response, I looked at these section but since the fiber optic cable isn't the communication or network cable and it is used for the measurement equipment using the optics + fiber optic cable which includes 400/440um-600/660um core diameter with coated jacket and then assembled into either PVC jacket or conduit like stainless steel interlock jacket with PVC sheathing(not MC-HL). NEC section 501.10(A)(1)(e) only specify the fiber used in either plenum or riser application. Our fiber optic probe will be sitting very next to the instrument and running to a measurement point for a short distance(max ~2m) so I was wondering if the non-certified fiber optic cable are ok to run with CID1 approved FMC from Crouse-hinds or ABB with standard rigid conduit fitting with proper sealing material at the enclosure end since the two fiber diameter of 1mm each won't fill the conduit more than 25% ?
 

rbalex

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Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Section 501.10(A)(1)(e) says what Types are permitted, other Types aren't. You may be able to have your NRTL certify your intended installation as an assembly.
 

rbalex

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Location
Mission Viejo, CA
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I note Section 501.10(A)(1)(e) does not limit optical fiber Types to "plenum or riser application" - look again,
 

Srknet

Member
Location
NY
Occupation
R&D engineer
I note Section 501.10(A)(1)(e) does not limit optical fiber Types to "plenum or riser application" - look again,
Hi Bob,
yes, it doesn't say plenum or riser but the type of all those fibers (OFNP, OFCP, OFNR, OFCR, OFNG, OFCG, OFN, and OFC) are for to install in the raceway which is I understand that as an plenum or riser only, isn't it ?. Please attached see the example of the fiber optic cable. Customer prefer it to have CID1 certified but since it is not an electrical cable and carrying only dispersed halogen light, having it in the PMA Ex type conduit or FMC wouldn't be sufficient since the cable itself contained inside the SS interlock jacket ? We have UL involved, I asked UL 2225 but they saying it is only for MC-HL or ITC-MC-HL, the rest fall under UL 1569 so I am kind of back and forth to decide whether do we really need to certify or not because I read in one or other blog that you can even call it as inherently safe if there is no conductive wire. The cable will have UL approved Flame retardant PVC sheathing anyway. All these driving me crazy so I am trying to understand.
 

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rbalex

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Location
Mission Viejo, CA
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Professional Electrical Engineer
Raceway is a defined term in Article 100. It is fairly general and does not necessarily imply or require it to be a plenum or riser.

Under Section 501.10(A)(1)(e), no matter how these cables are listed or labeled, they would still be required to be in a raceway for field installation in Class I, Division 1. Listing them specifically for Class I, Division 1 is not required. Flexibility could be an issue See Section 501.10(A)(2)(a). The cables shown are subject to Section 501.30. Grounding/bonding is a BIG deal in all classified locations.

EDIT ADD:
I read in one or other blog that you can even call it as inherently safe if there is no conductive wire.
I believe they meant Intrinsically Safe. (Article 504) That is a whole other can of worms you probably don't want to get involved with.
 
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Srknet

Member
Location
NY
Occupation
R&D engineer
Raceway is a defined term in Article 100. It is fairly general and does not necessarily imply or require it to be a plenum or riser.

Under Section 501.10(A)(1)(e), no matter how these cables are listed or labeled, they would still be required to be in a raceway for field installation in Class I, Division 1. Listing them specifically for Class I, Division 1 is not required. Flexibility could be an issue See Section 501.10(A)(2)(a). The cables shown are subject to Section 501.30. Grounding/bonding is a BIG deal in all classified locations.

EDIT ADD: I believe they meant Intrinsically Safe. (Article 504) That is a whole other can of worms you probably don't want to get involved with.
Thanks Bob, I will check all you recommended. I am not sure that intrinsically and inherently terms can be interchangeable but I believe intrinsically safe is belongs to limiting electrical energy but when it comes to optical energy, it follows UL/IEC 60079-28, which can be protected by methods like op "is", "pr" and "sh" so I was referring to optical energy since we have a small halogen source inside which doesn't emit any focused or coherent light but just diverged and dispersed light, I thought that we could list it as op "is" and if we do provide mechanical protection to fiber then we could list it op "pr".
I really appreciate your quick feedback and advise.
 

rbalex

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Location
Mission Viejo, CA
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Professional Electrical Engineer
I'm fairly familiar with Intrinsically Safe systems BUT if that isn't what the "other blog" meant; it isn't "inherently safe" either since there is no NEC method to evaluate it. Section 501.10(A)(1)(e) encompasses what is permissible in Class I, Division 1 for Optical Fiber installations.

While I said, "...there is no NEC method to evaluate it."; that isn't absolutely true. I did mention having UL evaluate the installation as an assembly in Post #4. That is more-or-less addressed in Section 500.8(A)(1). Depending on the level of risk you are willing to take, Section 500.8(A)(3) may be an option.
 

Srknet

Member
Location
NY
Occupation
R&D engineer
As you said, there is no term " inherently safe" its all about intrinsically safe, and sure it is very touchy. the light source itself is an intrinsically safe so could be an op "is" but regardless of that we have to follow 501.10(A)(1)(e) guideline. UL also confirmed that the fiber optic cable doesn't need to be listed as CID1 but have to be evaluated as per NEC code you mentioned. thank you very much for shining the light on all these.
 
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