Class 1 Division 1 conduit entry

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kentirwin

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Norfolk, VA
In dealing with a new installation in a class 1 div 1 location, I have a listed class 1 div 1 enclosure housing pushbutton operators with no
threaded conduit entry provided. The enclosure will be pressurized. Is it permissable to "punch out" the enclosure and use a Myers hub fitting for the 1" conduit entry? Thanks for any help.
 
Re: Class 1 Division 1 conduit entry

I'm not really sure just what you have there but I am guessing you have a pressurized enclsoure with an appropriate controller on it.

You can punch new holes to your hearts content in the pressurized sheet metal enclosure as long as (at least in most cases) you put seals on them.
 
Re: Class 1 Division 1 conduit entry

In general, enclosures already listed for Class I are not suitable for field modifications and a UL qualified shop should make all drilling/taps to maintain the listing.

I confess, if you are using "Type X" pressurizing (NFPA 496) it probably would be a "safe" installation because there are so many other operating restrictions. And, as the "other" Bob pointed out, you could have used a general purpose enclosure in the first place.

The field modification you proposed would be unsuitable for "Type Y" pressurization, since it would not be suitable for Division 2 in the "unpressurized" state.
 
Re: Class 1 Division 1 conduit entry

Bob,

Can you clarify your statement re:; Type Y enclosures? Wouldn't a general purpose box, with internal components listed for Div. 2, and field drilled penetrations, be suitable for Div. 2 in the non-pressurized state?

Admittedly, I don't do much with Purged systems. Maybe I'm missing something.
 
Re: Class 1 Division 1 conduit entry

I am taking the stand with my associates that the myers hub is not legal in this installation based on 501.4 (3) - listed fittings, boxes ,etc. Crouse Hinds (who I understand bought Myers) lists the Myers hub for class 1 div 2 use but NOT div 1. But I'm still wondering if there is some exception I haven't seen.
 
Re: Class 1 Division 1 conduit entry

nhee,

I've been trying to figure out how to answer your question without being too convoluted.

As kentirwin described the enclosure, it was already listed for Class I. I assumed it was explosionproof. Why? Section 501.3(A) recognizes explosionproof and purged-pressurized enclosures for this application in Class I, Division 1. However, only explosionproof enclosures are "listed" for Class I. Purged-pressurized enclosures are "identified" as suitable.

I also assumed the internal equipment was not inherently suitable for Division 1 or 2. That may be a false assumption. However, if it is correct, then field modifying the enclosure voids the listing and it is no longer suitable for use in Division 2 as required by 501.3(B)(1)'s reference back to 501.3(A).

"Type Y" Pressurization permits using an installation initially suitable only for Division 2 in a Division 1 location. Since the field modification contemplated by kentirwin rendered the installation not suitable for Division 2, "Type Y" would not be appropriate.

That being said, if my assumption about the internal equipment were incorrect, then "Type Y" may be suitable.
 
Re: Class 1 Division 1 conduit entry

Bob,

I had assumed a General Purpose, Hoffman-style box with purge. Is there a situation where purge of a box that is already listed as explosion-proof would be required? Also, kentirwin mentioned "puch-out" of the enclosure, which led me rule-out a big explosion-proof box.

Also, OZ Gedney supplies field-drilling instructions with their explosion-proof Type YE junction boxes. Are you saying that if this field drilling is performed by someone other than a UL shop, the box is no longer listed?

KentIrwin, would an OZG style EYH "sealing hub" work for you? It is listed for Cl 1 Div 1.
 
Re: Class 1 Division 1 conduit entry

Originally posted by nhee:
Bob,
...
Also, OZ Gedney supplies field-drilling instructions with their explosion-proof Type YE junction boxes. Are you saying that if this field drilling is performed by someone other than a UL shop, the box is no longer listed?
...
Click to expand...
Yes, drilling per manufacture's instructions would be acceptable. I should add the drilling should have been done prior to installation of other equipment in the box. It's possible the entire assembly is listed.

[ January 05, 2005, 04:13 PM: Message edited by: rbalex ]
 
Re: Class 1 Division 1 conduit entry

The problem is not just the drilling but the tapping. Its very difficult to do in the field without the right equipment.

I'm not sure what Bob is referring to as a UL shop in this context.
 
Re: Class 1 Division 1 conduit entry

Originally posted by petersonra:
...
I'm not sure what Bob is referring to as a UL shop in this context.
Click to expand...
In this particular case it would be a shop,"...with the right equipment," authorized to modify the equipment per manufacture's instructions. There are shops out there beyond 508 and 347. A few refineries have them. Some are authorized to do their own "inhouse" xp motor rewinds too.

As you pointed out very few field operations have the ability.
 
Re: Class 1 Division 1 conduit entry

Trying to solve this problem via this Web site is not the way that I would want to go when you are in a classified hazardous area. T have worked for many years in a chemical plant doing classified work. There are many things to take into consideration, and trying this on a Web site is not the way that I would go.
 
Re: Class 1 Division 1 conduit entry

Thanks for the comments and suggestions all. The dilemma was solved when it was decided to take to a qualified shop to have a threaded hub installed.
Nhee - Thanks for the tip on the OZG sealing hub. Was not aware of it's existence. It is suitable for bottom entry only. I actually have one on the way in case the panel shop modification got nixed.
 
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