How do you do work in a classified area?

[factoryrat]

I am working in a room where a coal belt runs. The coal belt feeds 5 or 6 coal bins below it. The coal is used to fire some industrial boilers. The coal bins are closed off to the room I am working in at the present time.

The room is rated Class II division II. At this time the area has not run in about two weeks (summer shut down). A lot of work is being done to update the controls and other systems. The room has been cleaned. There is no coal dust in the air although there is some on the floors and everywhere else. My question is this. When not running the coal belt and all the other associated equipment is this room still rated Class II Division II? We are being told by some people it is. Some of us argue, in the room?s present state, it is not. If it is still rated Class II Division II this makes drilling holes in concrete for anchors and in steal almost impossible along with a lot of other task associated with making possible sparks. We also have two roof vents (4? x 6?) open and two doors that go to the outside open. Can we use 120 volt drill and saw motors without violating the NEC and endangering anyone?s life? There is a lot of fresh air available. I would like to hear some of the other opinions out there. Thanks.

 

[Rockyd]

Need Rbalex to swing by for a fair opinion. Would think the plant would have an engineer, who is qualified, to make an evaluation. Would think that it is not hazardous atmosphere post cleaning. To further reduce hazard, would get some sucker, and pusher fans, with elephant trunks if neccesary to move air in, and out.

Also, is this a confined space by legal definition?

Is everyone there a "qualified person" to be on the project?

Are masks provided?

Do you have meters for gas detection?

Is it that "sixth sense" bell going off in the back of your head?


We used to replace bottoms of 250,000 barrel tanks for the crude oil tanks in Valdez, Alaska. As long as all reasonable precautions, and risks are reduced, or eliminated, work can commence, and you can get the project behind you. The atmoshere doesn't have to be pretty, just safe.

 

[rbalex]

What concerns me most is that what you have described has only been Classified Division 2. The Standard of Classifying, Class II locations is NFPA 499. Section 3-1 States:

3-1 Division 1 Classified Areas.
3-1.1
If a dust cloud is likely to be present under normal conditions, the area should be classified as Division 1.
3-1.2
If a dust layer greater than 1/8 in. thick is present under normal conditions, the area should be classified as Division 1.
3-1.3
“Normal” does not necessarily mean the situation that prevails when everything is working properly. For instance, if a bucket elevator requires frequent maintenance and repair, this repair should be viewed as normal. If quantities of ignitable dust are released as a result of the maintenance, the area is Division 1. However, if that elevator is replaced and now repairs are not usually required between turnarounds, the need for repairs is considered abnormal. The classification of the area, therefore, is related to equipment maintenance, both procedures and frequencies. Similarly, if the problem is the buildup of dust layers without the presence of visible dust suspensions, good and frequent cleaning procedures or the lack thereof will influence the classification of the area.

Something else from NFPA 499 to consider:

2-2.1.2
While a dust cloud will ignite and explode readily in the presence of an open ignition source, dust layers, if undisturbed and not in direct contact with the ignition source, will not explode. However, if a small amount of dust is dispersed in the air at the ignition source, a small explosion will occur. The pressure wave from this explosion blows the dust layer into the air, and a larger explosion then takes place. It is often this secondary explosion that does the most damage.

Your location appears to actually be Division 1 from your current description.

That said, basically whatever classification is documented is still in place until new “proper” documentation is created – typically a “hot work” permit. See NEC Section 500.4(A). While you are in turn-around, with “good housekeeping” (getting the floor laden dust cleaned up) you can issue a permit to allow use of the drills.

 

[factoryrat]

Want to do job correctly

Want to do job correctly

I think you are right ? Class II Div 1. But I have no documentation.

I have little experience with classified areas. I just found out the company had a representative from the insurance company come out to look at job and help classify it. This guy came out after some of the other plant electricians expressed concerns on how the renovations were being installed. An example - we were running RMC with regular, nonclassified, condulet tees where we were adding new coal level sensors. The old, original stuff had tee-box fittings rated for classified areas. There were also sealoffs installed in the original installation. We are now adding sealoffs to the new install. Anyways the company insurance representative and the plant safety dept. said to mimic the original existing installation.

The trouble with this is no classification was given to this area.

Shouldn?t this area have a definite classification?

Can you drill into the side of an existing explosion proof enclosure (box) for a new conduit run? We did this and then we used a Myers Hub. Is this safe and is it legal?

Is there such a thing as an explosion proof Erickson? We used a regular one in a conduit run and some people questioned if the fitting was appropriate for Class II environment.

Can lengths of sealtight be used in the Class II area? I think it can ? What do you say?

I hope I convey my thoughts clearly and thank you for responses.

 

[rbalex]

First, you must have the area classification properly documented; it?s an NEC requirement and a serious OSHA fine without it. See 500.4 (A) again.

Second, having the insurer review it is excellent. I?m surprised they didn?t require documentation.

Coal is basically Group F, so fittings, boxes, etc. only need to be dusttight; even those that contain ?taps, joints, or terminal connections.? See 502. 10(A) (1) (4). Identified is a defined term and does NOT necessarily mean listed, labeled or even ?marked.? Your insurer should be able to make a good judgment.

Seals are not a big issue in Class II. In fact, with proper layout, you generally don?t need them at all ? even when you do they don?t need to be explosion proof. See 502.15.

Generally, field modifying an explosionproof box is prohibited. As I said, it is a generality; consult with the manufacturer.

I have no idea what an Erickson is.

Liquidtight flexible metal conduit with listed fittings (?Sealtight?) is permitted when properly applied. See 502.10 (A)(2)(2).

 

[rbalex]

BTW, is it possible the location is also Class I? That is not unusual with coal since there may be significant entrapped volatiles (basically the definition of Group F).

 

[factoryrat]

"I have no idea what an Erickson is."

Rbalex an Erickson is just a coupling (union). Used when you do not have room to screw conduit together.

Thanks for references and info.

 

[don_resqcapt19]

This is an erickson as opposed to a UNY or UNF (explosionproof union) shown here.
Don

 

[factoryrat]

Good info - thanks

Good info - thanks

Don,
Thanks for web pages and now I know an explosion proof union exist. Can you use an erickson in a Class II Division 1 area?

 

[rbalex]

"Ericksons" are simply in a subcategory of threaded rigid metal conduit, or threaded steel intermediate metal conduit; they are acceptable in both Division 1 and 2. See 502.10(A)(1)(1) and 502.10(B)(1)(1)

 

[factoryrat]

Thanks Bob for info/response.

 

[factoryrat]

One more question.

One more question.

Can you drill into the side of an existing explosion proof enclosure (box) for a new conduit run? I did this and then I used a Myers Hub. Is this safe and is it legal?


502.10 (A) (1) (4) of NEC says:

?Fittings and boxes shall be provided with threaded bosses for connection to conduit or cable terminations and shall be dust tight. Fittings and boxes in which taps, joints, or terminal connections are made, or that are used in Group E locations, shall be identified for Class II locations.?


I have a hard understanding this language. After reading the above code section - can I or can?t I? A little more help please.

 

[tom baker]

Identified means according to the mfg instructions (look up art 100 definition of identified), its done however they require.

 

[rbalex]

Can you drill into the side of an existing explosion proof enclosure (box) for a new conduit run? I did this and then I used a Myers Hub. Is this safe and is it legal?.

In general no, but consult with the manufacturer.

502.10 (A) (1) (4) of NEC says:

“Fittings and boxes shall be provided with threaded bosses for connection to conduit or cable terminations and shall be dust tight. Fittings and boxes in which taps, joints, or terminal connections are made, or that are used in Group E locations, shall be identified for Class II locations.”.

I have a hard understanding this language. After reading the above code section - can I or can’t I? A little more help please.

From Art 100:

Identified (as applied to equipment). Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code requirement.
FPN: Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation.

​

Note the definition says listing and labeling are ome examples of ways; but they are not the only way. As Tom pointed out, the manufacturer's instructions may come into play. They may specify locations on the enclosure where field modifications are acceptable or suitable connection methods. In some cases, the AHJ (the insurer may be an AHJ) may simply "recognize" an application oe installation is suitable. In hazardous locations this may not be too common.

 

[megloff11x]

Hazloc work is tough. I just saw where Fluke was offering my $300 Model 87 DMM in a hazloc listed version for over a $1000.

If you ever had to access live connections, you'd have to get all the dust and fumes out first, which is usually impossible. You also have to worry about personal tools like DMMs, flashlights, or even sparks from metal on metal tools.

One good thing to do is a hazard review before you start. Analyze the area. Identify hazards. Identify what to do and what not to. Make a plan to proceed. If you find yourself needing to deviate from the plan, stop and do another review to insure that your new plan is safe.

A few buckets of coal aren't worth the consequences.

Matt

 

[petersonra]

Can you drill into the side of an existing explosion proof enclosure (box) for a new conduit run? I did this and then I used a Myers Hub. Is this safe and is it legal?


502.10 (A) (1) (4) of NEC says:

“Fittings and boxes shall be provided with threaded bosses for connection to conduit or cable terminations and shall be dust tight. Fittings and boxes in which taps, joints, or terminal connections are made, or that are used in Group E locations, shall be identified for Class II locations.”


I have a hard understanding this language. After reading the above code section - can I or can’t I? A little more help please.

I am not sure you cannot field drill and tap a box to add conduit entries to an existing XP box. Since you indicated you only drilled, but not tapped, I am guessing you did not tap. Even if you did, I don't know if a myers hub is suitable for this application.

 

[Rich Elec.]

I am going to agree with petersonra, I don't think that drilling a hole and using a myers hub is acceptable.
I know that T&B makes XP boxes with holes out of the top/bottom/side.

 

[petersonra]

I have always bought XP boxes with the tapped holes already in them, but I seem to recall they came with instructions on where, how many, and what size holes could be drilled and tapped in the enclosure walls. That is why I think maybe you can make your own tapped holes. But, it has been a long while since I have used any so maybe the rules have changed.

I am pretty sure they have to be tapped.