Question about Class I Diviision II

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ammklq143

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Iowa
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Electrician
I have a customer that's considering updating one room in the plant to Class I Division II and wants me to give him a cost estimate. As of now he has EMT conduit with set screw fittings and normal J boxes with knockouts, etc. I have a few questions.

Does all of the conduit need to be changed to IMC or RGS with threaded couplings?

Do the boxes need to be changed from the regular steel J boxes?

There are a couple GFCI receptacles that are flush mounted in nail on boxes inside the wall so the wiring for them is also inside the wall. I don't know if it's NM or what. Should I disconnect them and run conduit to new ones or can I leave them in place with a certain type of cover on it or....?

They have a mixer with an open blade disconnect on one of the machines which also has a couple motors mounted on it. Does that disconnect need to be rated Class I Division II? Are those motors going to be ok in this environment? I think the code book defined this area as an area with contained flammables or something so I may be going overboard with my thinking.

Any help or information would be greatly appreciated.

Thank you.
 
EMT is not permitted in a Class I, Division 2 area. Standard boxes are ok if there are no arc producing devices. Standard GFCIs are not permitted in that type of area. If the mixers have single phase motors, they will need to be explosion proof motors.

There are a lot of details for the electrical installation in classified areas. if you have not worked on that type of installation in the past, you should see if you can partner up with someone who has.
 
I guess I would start with how someone decided this was a Class 1 division 2 area. It seems to me if there's an open tank with a mixer in it the immediate area around that tank might well be Division 1.
 
petersonra said:
I guess I would start with how someone decided this was a Class 1 division 2 area. It seems to me if there's an open tank with a mixer in it the immediate area around that tank might well be Division 1.
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The owner said he a safety auditor told him it was Class I Division II. The mixer has a top that closes on it when mixing. It didn't appear to be a sealed lid. More of a lid that closes to prevent splashing possibly.
 
don_resqcapt19 said:
EMT is not permitted in a Class I, Division 2 area. Standard boxes are ok if there are no arc producing devices. Standard GFCIs are not permitted in that type of area. If the mixers have single phase motors, they will need to be explosion proof motors.

There are a lot of details for the electrical installation in classified areas. if you have not worked on that type of installation in the past, you should see if you can partner up with someone who has.
Click to expand...

Thanks for the info. That's the impression I got from looking at the code book too. So.....all of the EMT conduit would have to be replaced with IMC or RGS. What type of GFCI is suitable?

Thanks again.
 
ammklq143 said:
Thanks for the info. That's the impression I got from looking at the code book too. So.....all of the EMT conduit would have to be replaced with IMC or RGS. What type of GFCI is suitable?

Thanks again.
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A very expensive one listed for use in Class I areas.
 
It sounds like the owner is saying "you tell me what I need to make this area compliant if it is class 1, div 2." That is a loaded question.

To this i would ask the following question, what are the limits of classification? IMPO, answering that question is the job of a engineer regularly involved in applying NFPA to industrial installations. Maybe I am being alarmist or paranoid, but it seems unfair to expect an electrician to do it. The limits will have a significant impact on the cost of bringing the area up to current NFPA code.

Consider speaking with the local AHJ (electrical inspector and fire marshall) to see what they normally expect to see in terms of fire protection in such an installation (The NFPA code might require a fire alarm system(!!!), combustible detection with annunciation) because it needs to be taken into consideration before submitting a price.

That being said, NFPA isn't really a hard and fast code unless it is a new facility. We run into problems all the time when an rehabilitating an existing facility that is changing classifions. We try to keep as much as we can out of the classified area so regular equipment can be used-not always possible. Most of the time changing the classification of an existing facility results in exorbitant cost without much increase in fire protection. The AHJ should be satisfied that "reasonable means to prevent fires" are implemented for existing facilities.

ammklq143 said:
Does all of the conduit need to be changed to IMC or RGS with threaded couplings?
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Yes, in addition-you need to install seal offs whenever you transition from one classification area to another. they need to be filled with chico after the wires are pulled. Meaning, if you transition from class 1 div 1 to class 1 div 2, you have to seal off. If you transition from class 1 div 2 to unclassified you have to seal off. The seal off has to be before any type of fitting. The thought process in sealing off is to prevent explosive concentrations of gas from propagating through the conduit system.

ammklq143 said:
Do the boxes need to be changed from the regular steel J boxes?
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Not if you do not make any terminations inside the boxes. The moment you have anything capable of producing a spark, it must be NEMA 7.

ammklq143 said:
There are a couple GFCI receptacles that are flush mounted in nail on boxes inside the wall so the wiring for them is also inside the wall. I don't know if it's NM or what. Should I disconnect them and run conduit to new ones or can I leave them in place with a certain type of cover on it or....?
Click to expand...

Put a pull box, then route to a seal off, then a receptacle listed for use in class 1, div 2 areas. Or consider removing the receptacles altogether and locate new ones outside the classified area. Tell the owner to get a 100 ft extension cable. It will be far cheaper.

ammklq143 said:
They have a mixer with an open blade disconnect on one of the machines which also has a couple motors mounted on it. Does that disconnect need to be rated Class I Division II? Are those motors going to be ok in this environment? I think the code book defined this area as an area with contained flammables or something so I may be going overboard with my thinking.
Click to expand...

Disconnect must be NEMA 7. Motors must be explosion proof. Is there any instrumentation & control that needs to be upgraded to class 1, div 2?

ammklq143 said:
What type of GFCI is suitable?
Click to expand...

This type

TLDR; More questions need to be asked. Someone needs interpret the applicable NFPA code and identify the limits (volume) of classification and the requirements (Fire alarm, gas detection, etc.). Only then can you figure out what materials and methods you will use. It should be up to an engineer, not an electrician.

Additional reading - Class and Division: Don't Break Rank on Your Next Installation by Mike Holt, 2006
 
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GoldDigger said:
That takes care of the receptacle, now what about the OP's question on a GFCI? Does it have to be remotely located or are there any that can go in a classified area?
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Try this one.

Heh, I got so caught up in everything else I did not see it was GFCI..

OP please be aware you need special cords to plug into these bad boys. It is generally not recommended to be operating power tools in a classified area, but that is up to owner's O&M to make determination on. There is a UL book about plug in and battery powered devices for use in classified spaces.

Fine Print:
Each receptacle's contacts are deep recessed to avoid accidental contact and will accept standard non explosion proof plugs that are NEMA 5-20R, or 6-20R compatible although explosion proof plugs must be used to preserve explosion proof approval in hazardous environments. Ordinary location plugs will NOT activate this cord's explosion proof receptacles.

Inter-Compatibility: These cords use T style plugs and will work with non-explosion proof standard receptacles and plugs (NEMA 5-15R, 5-20R, or 6-20R) but will not work with standard 120V wall outlets. The included plugs and receptacles are cross-interchangeable with Crouse Hind™ part# ENP5201 plugs and receptacles and Hubble-Killiark part# UGP-20231 ACCEPTOR® plugs and receptacles. Any equipment requiring these C-H or H-B plugs should work with these cords. Due to possible manufacturer changes we cannot guarantee interchangeability although we have made every effort to ensure cross compatibility correctness.
 
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