Class I Div 2 Grp. B

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scott minter

Member
Location
Kennedy Space Center, Florida
Occupation
Associate Engineer
Good Afternoon

I have an area that has been classified Class I Div 2 group B

Does a panel installed in this area need to be explosion-proof ?

I am using the 2014 NEC and and looking at 501.115 (B)(1) and
I do not meet any of the 1-4 exceptions.

Thank you for your help. Scott
 

rbalex

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Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Of course it depends on what's in the panel but, since you are referring to Section 501.115(B) with none of the "exceptions" applying, I'm assuming there is a switching or current interrupting device of some kind. If that be the case, then an enclosure identified for Class I, Division 1 must be used.

NOTE: Explosionproof is not the only protection technique identified for Class I, Division 1 [See Section 500.7] but it is the most common and, in my opinion, the most reliable. Further note, if you do use an explosionproof enclosure, it must also be specifically suitable for Group B. [500.8(B)]
 

Ragin Cajun

Senior Member
Location
Upstate S.C.
A panelboard in a classified area is EXPEN$IVE AND DIFFICULT TO WORK ON.

I have worked in various industrial plants and it at all possible, put the panelboard OUTside the classified area.

If it HAS to go in the classified area, there are some newer style panelboards for classified areas that have the breaker in a factory sealed area with the wiring in a separate compartment. That's the way to go.


RC
 

scott minter

Member
Location
Kennedy Space Center, Florida
Occupation
Associate Engineer
Thank you for the help.
The panels were already in place when the area
changed classification .

The panels are 4X gasketed and well maintained
i put seal offs on the conduits leaving and
entering the panels . We are considering purge
and pressuratizion.
Any thoughts.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Thank you for the help.
The panels were already in place when the area
changed classification .

The panels are 4X gasketed and well maintained
i put seal offs on the conduits leaving and
entering the panels . We are considering purge
and pressuratizion.
Any thoughts.

That would seem to be one option. Keep in mind it will suck up a lot of air and compressed air is not cheap.

Another option would be to install the whole thing inside of an XP enclosure.

Really the best answer is to see if you can move it. It might also be possible to have a knowledgeable person look very closely at how the area came to be classified this way and see if maybe there is justification to unclassify where the panel is located.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
That would seem to be one option. Keep in mind it will suck up a lot of air and compressed air is not cheap.

Another option would be to install the whole thing inside of an XP enclosure.

Really the best answer is to see if you can move it. It might also be possible to have a knowledgeable person look very closely at how the area came to be classified this way and see if maybe there is justification to unclassify where the panel is located.
Pressurizing is probably your best overall option, keeping petersonra's comments in mind.

I would also note that simply sealing without pressurizing a non-explosionproof enclosure is useless; it only guarantees that you will blow the doors off and ignite the surrounding location if an internal explosion occurs.

I very much concur with reviewing how the location was reclassified in the first place. Over-classifying is a very common problem when it is done "just to be safe".

Relocating and/or reviewing the classification can cause additional problems with boundary seals.
 

scott minter

Member
Location
Kennedy Space Center, Florida
Occupation
Associate Engineer
Thank you for all the help.

https://www.youtube.com/watch?v=J1wvdA56bks

These are umbilicales we test.

The classification was made early on and now has shifted, the determination is made with the AHJ.

Now electrical equipment I had outside classified areas have fallen inside due to new piping, flowing LH2.

We have plenty of GN2.

The the system we are going to install : Pepperl+Fuchs 1000 series type Z purge system.

I think this would "fix" the panel issues ?

I also have a well maintained, gasketed SS splice/pull box. Also now in class I div 2 grp. b area.

Am I correct that I do not have to do anything with this box if no conduits leaving the box leave the area?

Thank you again. Scott
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Cool animation.

Well, let's see. Unless the electrical area classification was determined directly from Article 511 to 515, in my nearly 50 years experience, I've never seen a Building Official AHJ classify in any manner other than, "just to be safe." I've seen one or two Fire Marshalls do a credible job. I suspect this location has been overclassified; but I can't tell without knowing the full mechanical set up of the piping. I have done a few launch pads at Vandenberg, but never involving an umbilical assembly.

Nevertheless, a Type "Z" pressurization system sounds fine.

As long as there are only terminals inside the junction box, it may be any "ordinary location" enclosure type that is otherwise appropriate for the location. It doesn't need to be pressurized nor does it require seals. Your raceways will require seals at the boundaries; however, they are not required to be explosion proof.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
WOW! Videos are humbling. Reminds me how small my little inspection world is :)
 

scott minter

Member
Location
Kennedy Space Center, Florida
Occupation
Associate Engineer
Good Afternoon, I was hoping to squeeze one more question in if you don't mind.

In the newly classified area I have described our instrumentation group installed round cover
Class I Div 2 wrong Group. boxes .

Looking at 501.10(B)(4) They could have installed any box, nothing in the box but splice or pull point.
My concern is on the walk down can it be said that these boxes are not rated for the area because they are the wrong group ?

Thank you. Scott
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Good Afternoon, I was hoping to squeeze one more question in if you don't mind.

In the newly classified area I have described our instrumentation group installed round cover
Class I Div 2 wrong Group. boxes .

Looking at 501.10(B)(4) They could have installed any box, nothing in the box but splice or pull point.
My concern is on the walk down can it be said that these boxes are not rated for the area because they are the wrong group ?

Thank you. Scott
Keeping in mind they weren't required to be identified for Division 1, see Section 500.8(C)(6)(a).

Edit add: This may be a bit convoluted, but hazardous location equipment is not necessarily identified for outdoor locations. That is, an enclosure marked for Class I, is only suitable for indoor installations unless it is also marked as an enclosure type that is also suitable for outdoor installations. See Section and Table 110.28.
 
Last edited:

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
Thank you for all the help.

https://www.youtube.com/watch?v=J1wvdA56bks

These are umbilicales we test.

The classification was made early on and now has shifted, the determination is made with the AHJ.

Now electrical equipment I had outside classified areas have fallen inside due to new piping, flowing LH2.

We have plenty of GN2.

The the system we are going to install : Pepperl+Fuchs 1000 series type Z purge system.

I think this would "fix" the panel issues ?

I also have a well maintained, gasketed SS splice/pull box. Also now in class I div 2 grp. b area.

Am I correct that I do not have to do anything with this box if no conduits leaving the box leave the area?

Thank you again. Scott


Could I please come work with you? NASA and space exploration has fascinated me since I was a kid.


SceneryDriver
 

scott minter

Member
Location
Kennedy Space Center, Florida
Occupation
Associate Engineer
Right now I need all the help I can get. I am just an onsite contractor for NASA but I love it and it is a very rewarding place to work.

I have another question please I am attaching a photo of a cable grip I would like to use to seal a position sensor.

I have a valve with two position sensors on each side that in the instruction say seal within 18 inches i am wondering if this would count as sealing

or if it means adding a fitting and pouring. OK i could not attach the photo if you type in this part number it takes you to the cable gland

11691122070 Hummel

Thank you again .
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Right now I need all the help I can get. I am just an onsite contractor for NASA but I love it and it is a very rewarding place to work.

I have another question please I am attaching a photo of a cable grip I would like to use to seal a position sensor.

I have a valve with two position sensors on each side that in the instruction say seal within 18 inches i am wondering if this would count as sealing

or if it means adding a fitting and pouring. OK i could not attach the photo if you type in this part number it takes you to the cable gland

11691122070 Hummel

Thank you again .
I can't find the product you're referencing.

This termination may be used as a seal fitting for most cable-types permitted in classified locations. It may also be fitted with a cable grip.

This is not a product endorsement; several manufacturers make similar products.
 
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