INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login




Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

TGHNylon (Chemical) (OP)
24 Jan 05 12:23
I have an area classified as Class 2, Div 2, Group G for occasional dust.  We have plenty of TEFC motors in this area, but no XP motors.  Is this appropriate?  The only guidance I can find says TEFC motors are suited to dusty environments and that XP motors are only needed in Class 1 environments.  Class 2 is termed Dust Ignition Resistant.  
Then again, I have read that TEFC motors are not suitable in hazardous locations.  Am I OK with plain, generic TEFC?

Also, am I good to use a NEMA 4 enclosure, knowing that it is not suited in 'hazardous' locations, but is dustproof?  Do I need to go with NEMA 9 which is used for Class 2 Div 1 Group G even though I am in Div 2?

Thanks for your helpful response.
Helpful Member!  aolalde (Electrical)
24 Jan 05 16:43
If you r location is Class-II, Division 2 ( not dust blanketed) you are allowed to use TEFC motors.

The USA NEC States for Motors and Generators; “Section 502-8(b). In Class II, Division 2 locations, motors, generators and other rotating electrical equipment shall be totally enclosed nonventilated, totally enclosed pipe ventilated, totally enclosed fan cooled or dust-ignition-proof for which maximum full-load external temperature shall be in accordance with Section 500-3(d) for normal operation when operating in free air (not dust blanketed) and shall have no external openings.”
“NEC Section 500-3(d) states: “ Class-I I  Temperature. The surface temperature marking specified in (b) above shall be less than the ignition temperature of the specific dust and in no case shall it be higher than the temperature given below for Groups E,F and G. ( See Clasification of Gases, Vapors, and Dusts for Electrical Equipment in Hazardous(classified) Locations NFPA 497M for minimum ignition temperatures of specific dusts.) “
jraef (Electrical)
24 Jan 05 21:26
That is about as good an answer as you are going to get. Bravo.

"Venditori de oleum-vipera non vigere excordis populi"


TGHNylon (Chemical) (OP)
25 Jan 05 8:22
Thanks, aolalde.  That is quite helpful.    Can I use NEMA 4 enclosure?
rbalex (Electrical)
25 Jan 05 18:07
First, aolade's response is solid. For what it's worth UL began listing motors specifically for Division 2 (Both Class I and II) sometime last year - they are NOT XP, Essentially, they are TEFCs that they have tested.

More info here:
http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=PTHE.GuideInfo&;ccnshorttitle=Motors,+Division+2+for+Use+in+Hazardous+Locations&objid=1074049147&cfgid=1073741824&;version=versionless&parent_id=1073991469&sequence=1

Click on the "View Listings" in the upper left-hand corner for a list of the manufactures.
aolalde (Electrical)
25 Jan 05 18:11
My personal opinion is that enclosures must be “Dust tight” not only NEMA 4.

The National Electric Code Section 502-6(b) “In Class-IÍ,  Division 2 locations, enclosures for fuses, switches, circuit breakers, and motor controllers, including pushbuttons, relays, and similar devices, shall be DUSTTIGHT.”

NEMA 250-2003 defines Enclosures Type 4 as “to provide a degree of protection against falling dirt, rain, sleet, snow, windblown dust, splashing water, and hose-directed water; and that will be undamaged by the external formation of ice on the enclosure.”

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close