Need clarification repair garage

[loosegoose22]

Looking at the NEC '05 Handbook for 511.3(B)(3)(1) it list aclassified area as up to a level of 18 inches above floor. Then if we look in Article 501.15(B)(2) exception 1 for seals, it states "Metal conduit that contains no unions,couplings,boxes,or fittings, and passes completely through Class I, Div 2 location with no fittings less than 12 inches beyond each boundry, shall not be required to be sealed if the termination points of the unbroken conduit are in an unclassified area." In the commentary diagram it shows a highlighted are as classified (assuming 18 inches) then the bottom of a box greater than or equal to 12 inches. From this do we figure that the bottom of the box, fitting,etc has to be a minimum of 30 inches above floor to meet this exception?
thanks in advance

 

[rbalex]

Your understanding is correct. The Handbook's Exhibit 511.1 is an example of both cited Sections under the 2005 NEC. You may want to review the 2008 NEC Section 511.3. They have significantly changed the overall text. It probably won't affect you but revierw it anyway; especially if there is any dispensing involved.

 

[loosegoose22]

Thanks Bob. Don't have access to an '08 but will keep that in mind. BTW, my situation was conduit inside a grouted masonry wall(unclassified in the '05) terminating into a box the contractor installed 18 inch to center AFF.

 

[rbalex]

Are you saying the raceway NEVER ran through a classified area?

 

[loosegoose22]

Affirmative, the raceway never went through a classified area but the box opening is within 18 inches of finished floor.

 

[rbalex]

If this weren’t a garage, I’d ignore it completely. In truth, I’d ignore it altogether since there are several competing and a bit conflicting philosophies going on. You have to draw the line somewhere and I believe the 12” requirement in 501.15(B)(2) Exception No. 1 effectively moves the Division 2 boundary. But text is text.

Basically the only real concern are Sections 511.4 and 7 and 18” or 30” is irrelevant.

Edit: Added reference to Section 511.4 since I reread the previous comment and realized the box is within the defined classified location. This also brings up other possible boundary issues. Hard to tell from the current description as I understand it.