Zone Crossing

[abusaleh]

As per 505(c)(1), crossing from class 1 zone 2 to an unclassified area, sealing fittings are required on the boundary (not more than 10 ft away), I read the exception and had an understanding that if the run is fully in threaded conduit system with no fittings or conduit bodies, the sealing fittings are not required? Is this correct.

If the run was direct buried, can we install the sealing fitting on the other end (the unclassified area side)?

Also, in exception 4 or 5 to this point, boxes containing splices or terminations were highlighted to be explosion proof (or this is the way I understood it), is the reason these being heat generation point if getting loose or open?

Best Regards

 

[rbalex]

Re: Zone Crossing

Originally posted by abusaleh:
As per 505(c)(1), crossing from class 1 zone 2 to an unclassified area, sealing fittings are required on the boundary (not more than 10 ft away), I read the exception and had an understanding that if the run is fully in threaded conduit system with no fittings or conduit bodies, the sealing fittings are not required? Is this correct.

If the run was direct buried, can we install the sealing fitting on the other end (the unclassified area side)?

Also, in exception 4 or 5 to this point, boxes containing splices or terminations were highlighted to be explosion proof (or this is the way I understood it), is the reason these being heat generation point if getting loose or open?

Best Regards

I?m having trouble with your citations. I assume your are referring to Section 505.16(C)(1)(b), There are four Exceptions, not five, and each Exception as a whole is ?stand alone? in application. You appear to be referring to either Exception 1 or Exception 4, subparts 4 and 5. If it is Exception 4, all subparts apply to the whole Exception. You also appear to be referring to the 2005 NEC.

Exception 1 applies only where both ends of the conduit run terminate in unclassified locations. Theoretically, this would limit most such ?runs? to be 8? through the classified location for ?standard? conduit lengths of 10?. (This "standard" length is actually the basis for the 10? limit in the main text) However, UL listed RMC can be of any length and I have seen manufactured lengths up to 25?. The most common application for Exception 1 is for ?stub-ups? that pass entirely through an 18-24? high Zone 2 at grade from an ?unclassified? underground to an ?unclassified? area aboveground. .

Note: This is a general application; some specific standards such as NFPA 30A treat the location below a classified location as Zone 1/Division 1. See Figure 514.3.

Exception 4 has no underground application. See the first statementof the main text ("Segments of aboveground conduit systems...") and subpart (3).

[ May 02, 2005, 11:43 AM: Message edited by: rbalex ]