Class 1 Div 1 Group A

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bnd

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I have school job I'm bidding. Its a Ag. shop and it has a welding room that is being classed as a Class 1 Div 1 Group A location.It has welding stations with exhaust fans over them for both gas and arc welding.
Now I look at this as a Class 1 Div 1 Zone 2 area and would like to keep outlets above vapor plane, put can't find vapor plane for Group A gas.
Also it seems strange to have a welding class room a Class 1 Div 1 location.Welding is an ignition source.
BND
 

rbalex

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Re: Class 1 Div 1 Group A

The tendency to over-classify is enormous and then everyone spends too much energy attempting to avoid the implications of the classification. It is best to classify properly in the first place.

As you have described it, the entire room is classified and you must install outlets listed for Class I, Group A - there is NO "vapor plane."

Group A is especially difficult to deal with. The choice of "approved" equipment is extremely limited.

I doubt I would have classified the room at all, but it is not my call.

BTW there is no such thing as Class 1 Division 1 Zone 2.
 

bnd

Member
Re: Class 1 Div 1 Group A

Bob,
If its a Group A how can they weld in there ?
Sorry its Class 1 Zone 2 ( 505.5/3 ).
BND
 

rbalex

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Re: Class 1 Div 1 Group A

Originally posted by bnd:
...
If its a Group A how can they weld in there ?
...
BND
Good question. As I said in my original reply, I believe the room is over classified.

Even a Division 2 or Zone 2 location would require listed Class I, Group A receptacle outlets. So would lighting fixtures and any other "arcing, sparking, or heat producing" ELECTRICAL equipment. In theory, gas welding is not covered by the NEC, but arc welding is.

Since 1999 the NEC has required "proper documentation" for Classified locations. [500.4(A)] FedOSHA has required it for Process Safety Management since the mid - 1980's. Assuming the "shop teacher" is a school employee OSHA could require it now. It is retroactively enforceable even if it were not required when the shop was originally classified.

I doubt much of the equipment in the room is actually suitable for Group A.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Class 1 Div 1 Group A

Originally posted by bnd:
Bob,
If its a Group A how can they weld in there ?
Sorry its Class 1 Zone 2 ( 505.5/3 ).
BND
The same way you weld anywhere else. You plug in the welder and go to it.

:)

Normally in most plants when you need to weld in a classified area you need a hot work permit, a fire watcher, and a gas detector.

You first get the permit describing the work to be done and what safety precautions are to be taken. someone trained to use the gas detector goes out to the area being welded in and determines it is safe to do so. then some kind of warning is put in place (tape or a flashing beacon are common), then you weld. the fire watch guy stands by with an extinguisher just in case.
 

jtester

Senior Member
Location
Las Cruces N.M.
Re: Class 1 Div 1 Group A

quote by Bob
Normally in most plants when you need to weld in a classified area you need a hot work permit, a fire watcher, and a gas detector.

I've designed vo-ag shops for a number of high schools in this area. They want to weld in wood shops, in auto repair shops, etc., and without restriction. When I bring up the requirements for welding in a classified location, they look at me like I speak in a foreign language.

I agree, that the welding shop by itself probably shouldn't be classified. That is great, because in my experience there is little or no hope that the shop teacher will have a system available to issue hot work permits.
Jim T
 

rbalex

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Re: Class 1 Div 1 Group A

One of my favorite quotes from NFPA 497:
3.4.4 When classifying buildings, careful evaluation of prior experience with the same or similar installations should be made. It is not enough to merely identify a potential source of the combustible material within the building and proceed immediately to defining the extent of either the Class I, Division 1 or Division 2; or Class I, Zone 1 or Zone 2 classified areas. Where experience indicates that a particular design concept is sound, a more hazardous classification for similar installations may not be justified. Furthermore, it is conceivable that an area might be reclassified from either Class I, Division 1 to Division 2, or from Class I, Division 2 to unclassified or from Class I, Zone 1 to Zone 2, or from Class I, Zone 2 to unclassified based on experience.
There's a similar statement in API RP500 - and that covers installations that generally are classified properly :D
 

bnd

Member
Re: Class 1 Div 1 Group A

Bob
None of the equipment is Group A suitable.Is the school then required to get new equipment or do they just change cord caps on their old welders and go for it.This all seems real off the wall to me, how do we this problem ?
Thanks every one for the input.
BND
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Class 1 Div 1 Group A

Originally posted by bnd:
Bob
None of the equipment is Group A suitable.Is the school then required to get new equipment or do they just change cord caps on their old welders and go for it.This all seems real off the wall to me, how do we this problem ?
Thanks every one for the input.
BND
it seems to me the answer is to get an engineer with experience in this field to review the situation and possibly reclassify the area.
 

rbalex

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Professional Electrical Engineer
Re: Class 1 Div 1 Group A

Originally posted by bnd:
Bob
None of the equipment is Group A suitable.Is the school then required to get new equipment or do they just change cord caps on their old welders and go for it.This all seems real off the wall to me, how do we this problem ?
Thanks every one for the input.
BND
Basically I concur with the "other" Bob. You are in the unfortunate position of telling the school that the entire room is non-compliant - however, the "fix" is fairly straightforward and will save them a lot of money. If the classification is left ?as-is,? ALL electrical equipment in the room should be upgraded. With regard to the shop, the NEC does not give specific instructions on how to classify it; however, once classified, the NEC is very specific about the installation and currently the room is non-compliant.

Done correctly, part of the "proper documentation" I keep harping about is a reference to an appropriate standard for determining the electrical area classification. In this case, NFPA 497 is probably the best choice since it is the most general document.

Somehow you were told that the room was Class I, Division 1, Group A and, in theory at least, that was based on someone's educated evaluation. I believe it would be reasonable to have a qualified engineer reclassify the room as ?unclassified? with this proviso: Part of the ?shop training? is teaching the proper handling and connection of the Acetylene bottles.

If the shop is ?unclassified,? it can be done on the basis of NFPA 497, Section 3.4.4. I?ve already cited it above, but the engineer should review the whole document and operating regime of the shop before making the final decision.
 

bnd

Member
Re: Class 1 Div 1 Group A

New twist!!!!
Just got the long awaited " ADDENDUM ", they changed the classification to Class 1 Div 2 Group A.Big deal.Can't see where that changes a thing.
Also in that room they had exits & emg. lighting that were not vapor tight. I noted that in my RFI, so part of the addendum read " Provide 12v battery pack for exit and emergency lighting mounted adjacent to panel B & feed from existing emg. lighting CCT. 12v DC conduit from battery pack shall be sealed within 18" of hazardous boundary and shall feed emg. fixtures in hazardous area.
First doesn't the 10' rule for seal apply ? Second does the voltage change mean that the fixture inclosure doesn't need to meet Class 1 Div 1 Group A spec's.
BND
 

rbalex

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Re: Class 1 Div 1 Group A

If they have gone to the trouble of reclassifying, they should now have an electrical area classification document [500.4(A)] that defines all the boundaries. You have a right to it as an ?installer.? Without it the overall design is still noncompliant.

Division 2 does ease things up a bit. It gives you a wider choice of wiring methods and your fittings don?t need to be listed for Class I.

Acetylene is nasty stuff. It has a ?Group? all to itself. It is ignitable over virtually its entire flammability range (2.5% to 99.9%) and has an almost infinitesimal Minimum Ignition Energy (0.017 milli Joule) and Minimum Experimental Safe Gap(0.25mm).

One redeeming quality is that it has a reasonably high Auto Ignition Temperature (305C) and a fairly reasonable ?T Class.? (T2C). I still doubt the emergency lights can make that although they may have a shot with a remote battery charger. Other fixtures have a better chance and they don?t actually have to be explosionproof. See 501.9(B)(2) in general and 500.8(B) Exception 2 for fixtures specifically listed for Division 2.

The receptacles will still need to be listed for Class I, Group A. As a general statement, anything that is arcing, sparking, or heat producing (ASH) in its normal operation will need attention.

The 10? rule would normally apply [501.4(B) (2)] in absence of a Specified requirement. The engineer can specify less than 10'. The voltage change is irrelevant ? the reclassification is what mattered.
 

don_resqcapt19

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Illinois
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retired electrician
Re: Class 1 Div 1 Group A

Bob,
This doesn't make any sense to me. How can a room where you are normally using electric and gas welding equipment be a classified area? If I am the fire marshall or insurance company, I would not permit any welding operations in this room unless a safe work permit system is used, including the continuous use of combustible gas detectors.
Don
 

rbalex

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Re: Class 1 Div 1 Group A

Don,

You are right - it doesn't make sense.

I think I've pretty well established the idea that I would not have classified the room at all - but it is not my call, I'm not the Engineer of Record. I also said in my first post that the tendency of the inexperienced is to over classify and then attempt to somehow get around actually installing per the classification.

I'm not trying to design this room either - just reviewing a few salient points about "why" it doesn't make sense. Technically, the arc-welders themselves would need to be listed for Class I. The gas-welders aren't covered by the NEC.

Gas detectors have been recognized by the NEC but this application is not one recognized by 500.7(K).
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Class 1 Div 1 Group A

Originally posted by don_resqcapt19:
Bob,
This doesn't make any sense to me. How can a room where you are normally using electric and gas welding equipment be a classified area? If I am the fire marshall or insurance company, I would not permit any welding operations in this room unless a safe work permit system is used, including the continuous use of combustible gas detectors.
Don
You are probably addressing this to the other Bob, but I agree with you.

Most plants of any size require some kind of work permit to weld anywhere, regardless of area classification EXCEPT in areas designed to safely allow welding to take place.

The key is that if they design the area to be a safe place to weld in, and have the procedures in place, then they can weld.
 

rbalex

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Re: Class 1 Div 1 Group A

Don,

After reading the ?other? Bob?s response it dawned on me that I may have inadvertently accused you of inexperience. That certainly wasn?t my intention.

From NFPA 497:
3-3 Unclassified Areas.
3-3.1 Experience has shown that the release of ignitable mixtures from some operations and apparatus is so infrequent that area classification is not necessary. For example, it is not usually necessary to classify the following areas where combustible materials are processed, stored, or handled:
(a) Areas that have adequate ventilation, where combustible materials are contained within suitable, well maintained, closed piping systems
(b) Areas that lack adequate ventilation, but where piping systems are without valves, fittings, flanges, and similar accessories that may be prone to leaks
(c) Areas where combustible materials are stored in suitable containers

?
3-3.3 Open flames and hot surfaces associated with the operation of certain equipment, such as boilers and fired heaters, provide inherent thermal ignition sources. Electrical classification is not appropriate in the immediate vicinity of these facilities. However, it is prudent to avoid installing electrical equipment that could be a primary ignition source for potential leak sources in pumps, valves, and so forth, or in waste product and fuel feed lines.
While the list from 3-3 are only examples and none of them are specific to the room in question, a proper evaluation of the operation of the shop class would probably lead me to believe ?that the release of ignitable mixtures from some operations and apparatus is so infrequent that area classification is not necessary.

I too have experience with ?hot work? requirements in properly classified Division 1 and 2 locations and the precautions you noted are appropriate. I just don?t believe this room needs to be classified.

[ February 02, 2005, 12:31 PM: Message edited by: rbalex ]
 

don_resqcapt19

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Location
Illinois
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retired electrician
Re: Class 1 Div 1 Group A

Bob,
I too have experience with ?hot work? requirements in properly classified Division 1 and 2 locations and the precautions you noted are appropriate. I just don?t believe this room needs to be classified.
I agree that it shouldn't have been classified. I have the same issue with "repair garages" where the code requires classification, but welding, cutting, grinding and other activities that involve ignition sources are routinely performed with no precautions.
Don
 

bnd

Member
Re: Class 1 Div 1 Group A

What does the " Documentation " consist of and who is responsible for making it available to me.
This whole thing is sad. This is a very small school with little money and someone has taken it upon themselves to create a situation where by classing the schools new welding class room the school may not be able to use that class room at all. I know of no arc or gas welder that would meet requirements.The nature of welding is to cause an igniting arc.
bnd
 

rbalex

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Professional Electrical Engineer
Re: Class 1 Div 1 Group A

Both NFPA 497 (Section 3.7) and API RP500 (don?t have it with me at the moment) outline the process of electrical area classification.

At the end of the process you should have, as a minimum:

1. A plot plan or well-defined narrative that defines the boundaries.
2. The Class, Division or Zone, Group and maximum ?T-Code? for each defined set of boundaries.
3. A reference to the Standard used to determine electrical area classification. (Unless it comes directly from Articles 511 to 516, the NEC itself is not a good reference)

Other items that may be required ?as necessary:?
o Elevations
o Specific sources identified - especially if they create Zone 0, Zone 1 or Division 1.
o Intrinsically safe and nonincendive control drawings.
o A list of other criteria, such as ventilation, gas detection or maintenance expectations, that were used to reduce the ?basic? classification.

I believe this is the responsibility of the design professional, it definitely is if the Zone method is used.
 

bnd

Member
Re: Class 1 Div 1 Group A

Thanks to all for your help.We just went to bid with no change in classification. Oh Will, its just our tax dollars at work.Thanks again-BND
 
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