Devices and device enclosures above class 1 div 2 locations

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What type of devices and device boxes should I use above class 1 division 2 locations more specifically commercial garages. I have started a new commercial garage with an attached showroom. All of my receptacles are above the required 18" but the code in 511.7 states they need to be totally enclosed. I want to use 1900 boxes with rs covers. Is this ok? Also the owner wants floor boxes and this is not allowed unless rated vapor/explosion proof right?
 

kwired

Electron manager
Location
NE Nebraska
What type of devices and device boxes should I use above class 1 division 2 locations more specifically commercial garages. I have started a new commercial garage with an attached showroom. All of my receptacles are above the required 18" but the code in 511.7 states they need to be totally enclosed. I want to use 1900 boxes with rs covers. Is this ok? Also the owner wants floor boxes and this is not allowed unless rated vapor/explosion proof right?

Above 18" is unclassified, IMO 1900 boxes comply. From 511.7:

shall be of the totally enclosed type or constructed so as to prevent the escape of sparks or hot metal particles

It is not real clear, but just how often do you see escaping sparks or hot metal particles escaping from a switch in a 1900 box unless there is something seriously wrong?

They do give us these requirements, and act like we will blow the place up with the smallest infraction of those rules, yet same shop will have welders, torches, grinders, etc. that make a lot of sparks on a regular basis:slaphead:

These days smoking is often not allowed in workplaces, but not too many years ago we also had that kind of activity in the shop quite frequently.
 
Devices and device enclosures above class 1 div 2 locations

Yeah. its not clear. I think i am just going to use 1900 boxes. If you read on it says it does not apply to receptacles only switches and the like (makes a spark). Also the floor boxes would be out of the question in the showroom unless haz loc rated right?
 

kwired

Electron manager
Location
NE Nebraska
Yeah. its not clear. I think i am just going to use 1900 boxes. If you read on it says it does not apply to receptacles only switches and the like (makes a spark). Also the floor boxes would be out of the question in the showroom unless haz loc rated right?

Sorry I had comment on the floor boxes in mind then forgot to post them.

IMO the showroom is not a hazardous location. Your AHJ may want a 1 hr rated wall between the shop and showroom or something like that, but it is not something specifically mentioned in the NEC.

Chances are building codes will require the min 1 hr wall between the shop and showroom anyway.

You need to find out where AHJ is going to call the horizontal boundary of the classified location.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
If someone else answers before I do, I rarely add to a topic. I would like to confirm the following assumptions though: first, this is a minor repair garage. Second, there is adequate ventilation throughout as defined in 511.3(D)(1)(a). If these assumptions are correct, I fully concur with kwired.

An additional thought I seem to be repeating regularly now: the electrical area classification must be properly documented [Section 500.4(A)] This is also a FedOSHA requirement for new facilities.[29CFR1910.307(b)], While Maryland is a "State Plan" State, its OSHA rules are substantially the same as FedOSHA's.

In my experience, AHJs or their representatives are rarely qualified to classify locations although they are usually quite good at inspecting a properly documented location.
 
Lets assume there is not sufficient air flow (4 changes of air per hour) and this would be a major repair garage with lifts and the such attached to a showroom. This is a auto center with enclosed open face paint booths in one area (I know class 1 div 2 within certain measurements of the paint booth) one large general car service area and another area with 5 car lifts with overhead doors in all locations and a car showroom on the first floor. The service areas are on the basement level. All of these areas are attached with a joining walls with doors. There is a stairway that connects the showroom on the first floor and the basement level. There is no solid wall separating any of these areas. All of the areas are accessible to each other. I am assuming everything under 18" is going to be classified haz loc class 1 div 2. I am worried about the stuff mounter above the haz loc. On the prints every device is above 24" even in the showroom except for the floor boxes. For the device mounted above I am worried about 511.7. Also check out 511.2 and 511.7. There are no pits in this facility. If you give me your email I can send you a pdf version of the prints.:cool:
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Well, it's now a major repair garage without adequate ventilation with all the area classification requirements of Section 511.3(A), possibly including the showroom.

As I have told others before on this site, I don't "do" electrical area classifications without a fee. (Sending me the PDFs won't matter) You need to hire a qualified professional to fully document the electrical area classification. Often the facility's insurer can provide assistance.

The 1900 receptacle boxes above 18" are still fine. It isn't clear whether the showroom is classified or not.
 

kwired

Electron manager
Location
NE Nebraska
Lets assume there is not sufficient air flow (4 changes of air per hour) and this would be a major repair garage with lifts and the such attached to a showroom. This is a auto center with enclosed open face paint booths in one area (I know class 1 div 2 within certain measurements of the paint booth) one large general car service area and another area with 5 car lifts with overhead doors in all locations and a car showroom on the first floor. The service areas are on the basement level. All of these areas are attached with a joining walls with doors. There is a stairway that connects the showroom on the first floor and the basement level. There is no solid wall separating any of these areas. All of the areas are accessible to each other. I am assuming everything under 18" is going to be classified haz loc class 1 div 2. I am worried about the stuff mounter above the haz loc. On the prints every device is above 24" even in the showroom except for the floor boxes. For the device mounted above I am worried about 511.7. Also check out 511.2 and 511.7. There are no pits in this facility. If you give me your email I can send you a pdf version of the prints.:cool:

You have me a little confused, I think the service area is at the basement level, and the showroom is on first floor? If there is no major repairs going on at the first floor level then if there is a classified area it should only be at the basement level where the major repair center is, and of course there is a classified area associated with the paint booth, but you gave no details on that and I get the feeling it is all that much of a concern to you as far as topic of this thread goes.
 
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