Class 1 Division 2 1

[TAMEE]

Would you please direct me to any information we can find on the issue of "What are the steps/determinations that employer need to follow to classify the Electrical Class & Division?"

 

[peebee]

Environmental hazard is typically determined by either the insurance company or a safety engineer. Sometimes NFPA or other codes will also have specific requirements.

Generally, an area is classified hazardous based on the potential concentration of vapor or dusts in the atmosphere. Division 1 means the hazard is normally present, Division 2 means the hazard is usually present only during maintenance or in the event of an accident. Airlocks are often required for entry into Division 1 areas, those airlocks are typically classified Division 2. An entire room need not have the same classification, sometimes the volume located within the specified distance from a piece of equipment is classified. Similarly, if you are dealing with a heavier-than-air vapor, perhaps just the first few feet above the floor need to be classified.

See

http://www.appletonelec.com/Hazardous.htm

and

http://www.crouse-hinds.com/crousehinds/resources/codedigest.cfm

for some great additional information. The Crouse-Hinds link wasn't working at the time of this posting, but it's worth either waiting for the link to restore itself or calling Crouse-Hinds for a paper copy of their Code Digest.

NEC Articles 500 through 504 deal with installation requirements, but do not really address your question regarding when an area needs to be classified hazardous.

Hope this helps.

 

[peebee]

Oops, I just realized this was posted in the IEC forum, so maybe my post was not too relevant.

Similarly, this may not be relevant either, but just in case:

See NFPA 497, Recommended Practice for the Classification of Flammablle Liquids, Gases or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas,
and NFPA 499, Recommended Practice for . . . Dusts . . . .

 

[TAMEE]

Thank you.
The Entry/Exit Door for this area that is classified hazardous (Class 1, Division 2), can it be opened? Is there a requirement that they have to be so how many feet away?

 

[peebee]

The door can certainly be opened, people and equipment move into and out of operational classified areas all the time.

Please understand that my background is purely electrical -- you should check with mechanical engineers to verify if there are any applicable ventillation requirements.

I don't understand your questions "Is there a requirement that they have to be so how many feet away?", please rephrase.

Also, I should remind you once again that my experience almost entirely with US installations. My advice may not be applicable in other countries.

 

[ccaserta]

There is a great chart put out by FM that allows you to classify the area your interested in. Go to

http://www.fmglobal.com

and search for Expert guide to hazardous locations. The chart can be downloaded or you can have them send you one. The chart is easy to follow, good luck. Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360