Working space in existing buildings

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ryan_618

ryan_618

Senior Member
Location
Salt Lake City, Utah
I am working on a power-point presentation about working clearance, and I have run into something that I can't quite figure.

110.26(A)(1)(c) gives allowances for existing buildings to comply with condition 2 of the table when condition 3 would normally apply. I am assuming that perhaps condition 3 didn't exist in some earlier editions of the code? Could anyone tell me if my thoughts are right on this? Thanks in advance.
 
C

ccha9219

Senior Member
Re: Working space in existing buildings

the original code documents printed in 1897 I'm almost sure did not address condition three.
If you look at 70-1 it gives you a brief history of the code...
I hope this helps your project
ccha9219 :D
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: Working space in existing buildings

Ryan,
The section that you are asking about was originally Exception #3 to 110.16 and first appeared in the code in 1996. The proposal (1-156 in the 95ROP) asked for the exception to apply to all installations, both new and replacement, of this type in industrial occupancies. The substantiation stated that aisle type installations have been made for many years using the "condition 2" work space without any safety problems. The submitter also stated that many AHJs permit the use of "condition 2" work space for this application. CMP 1 accepted the proposal in principle and made a wording change so that the exception only applied to the replacement of existing equipment. The panel made it clear that aisle type installations, even where the live parts are behind metal covers, is a "condition 3" installation. As far as when condition 3 first appeared in the code, I don't know. My oldest code book is 1978 and it is in that one.
Don
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: Working space in existing buildings

Condition 1 ? Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating materials. Insulated wire or insulated busbars operating at not over 300 volts to ground shall not be considered live parts.
Condition 2 ? Exposed live parts on one side and grounded parts on the other side. Concrete, brick, or tile walls shall be considered as grounded.
Condition 3 ? Exposed live parts on both sides of the work space (not guarded as provided in Condition 1) with the operator between.
Click to expand...
I think this is a very good example of the code wording not even coming close to matching the panel's intent. How can anyone be expected to know that motor control centers with no exposed energized parts fall under "condition 3" if installed in a aisle type layout?????
Don
 
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