Classifications

mannyb

Senior Member
we have customer that stores flammable liquids some of the materials are stored in doors. They also have an area where they mix batches of products in totes with flammable liquids and nothing I asked them if the area was a Classified Area and they couldnt tell me yes or no. I was wondering who decided if area is to be designated a hazardous classification. I am not sure how to proceed. Im kinda worried about doing electrical in that area without proper instruction. I do know that if I mix Aluminum with Ammonium Phosphate that it will start a fire in that area.
 

wandwwonly

Member
Location
US
Occupation
electrician
we have customer that stores flammable liquids some of the materials are stored in doors. They also have an area where they mix batches of products in totes with flammable liquids and nothing I asked them if the area was a Classified Area and they couldnt tell me yes or no. I was wondering who decided if area is to be designated a hazardous classification. I am not sure how to proceed. Im kinda worried about doing electrical in that area without proper instruction. I do know that if I mix Aluminum with Ammonium Phosphate that it will start a fire in that area.
A good start is NEC 500.5

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rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
A better start is Section 500.4; especially Section 500.4(B) IN No, 2. An unqualified person attempting to classify from Section 500.5 will get it wrong.
 

kwired

Electron manager
Location
NE Nebraska
I must agree get someone qualified to do the classification or assume the worst possible classification.

storage in sealed containers often doesn't trigger any classification. Once you open containers or release contents in some manner you open the door for classification.

Go to a paint store, that they may have many cans of paint but no classification exists except at/near workstations where they do mixing activities with flammable type paints.
 

powerpete69

Senior Member
Location
Northeast, Ohio
Occupation
Professional Electrical Engineer
Qualified people will struggle as well, even that one "professional engineering firm" you know and trust.
Actual "area classification" drawings need to be done by one of these firms before you get started.

The reason I say these firms struggle, is because 4 different "qualified" guys will have 4 different opinions on the proper area classification and they will fight over it causing the area classification drawings to have to be re-created over and over, essentially throwing 100 hours of billable work out the window.

That being said, these are still the people you want to do the work because they at least have some clue. And perhaps having a few people challenging ideas is a good thing.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Qualified people will struggle as well, even that one "professional engineering firm" you know and trust.
Actual "area classification" drawings need to be done by one of these firms before you get started.

The reason I say these firms struggle, is because 4 different "qualified" guys will have 4 different opinions on the proper area classification and they will fight over it causing the area classification drawings to have to be re-created over and over, essentially throwing 100 hours of billable work out the window.

That being said, these are still the people you want to do the work because they at least have some clue. And perhaps having a few people challenging ideas is a good thing.
I don't have a lot of faith in average PEs to get these kind of things right. It's a specialty and needs a specialist taking a look at it. Just like you would not go to your family practitioner to have brain surgery done.
 
From experience, I can say that the "average" PE has no experience in area classifications. ;-)

Not a knock on them - there is no reason why they would. I don't have any experience in utilities - doesn't mean I'm dumb (though I frequently am), just means I don't have that experience. It's a specialty, just like area classification.

Unfortunately, it's not exactly an exact science. Differences of opinion can come up; the standards don't cover everything.

Still, the application you mentioned doesn't sound like rocket science. (Unless they're mixing up rocket fuel in those tubs, which I hope they're not.)


Anyway, I usually start with NFPA 497 and work my way out.

(I can say that since 500.4 IN Note 2 references that, so it's in the Code!)

At the risk of incurring forum wrath, there are also a lot of other standards that can provide some really good guidance. Only some of which are mentioned in IN Note 2.
 
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