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suitably cut off or effectively cut off for classified spaces.

H

Hyrax4978

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Nov 28, 2016
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Hartford, CT
I am trying to design a solution to the effectively cut off requirement for the separation and door ways between an existing hangar and existing adjacent space.
You can find it in the NEC 70 section 513.3.

I can not find where the term effectively cut off is defined so i know how to achieve this. while i can find on google it appears to be two series of doors, but i would like to have the actual text of where this comes from and i can not find it. The other option is a major electrical modification to the spaces adjacent to the hangar, and that would be an absorbanent cost.

any help would be greatly appreciated.

Thank you,
 
This one must have people stumped. Not even a sarcastic reply!
I searched NFPA for the term suitably cut off and effectively cut off and it comes up for repair garages also. But still can't seem to get a definition to save my life.

Thank you,
 
Hyrax4978 said:
This one must have people stumped. Not even a sarcastic reply!
I searched NFPA for the term suitably cut off and effectively cut off and it comes up for repair garages also. But still can't seem to get a definition to save my life.

Thank you,
Click to expand...
Given the complexity and the fact that a misinterpretation could have safety implications, I'd highly recommend consulting directly with the local AHJ and perhaps even getting a professional engineering consultation for this specific issue. This would not only provide clarity but also might offer alternative solutions that are code-compliant yet cost-effective.
 
513.3(D) Areas Suitably Cut Off and Ventilated. Adjacent areas in which flammable liquids or vapors are not likely to be released,such as stock rooms, electrical control rooms, and other similar locations, shall be unclassified where mechanically ventilated at a rate of four or more air changes per hour, or designed with positive air pressure, or where effectively cut off from the hangar itself by walls or partitions.

Effectively cut off means no doors. Suitably cut off would allow for a door with ventillation of four air changes per hour or designed with positive air pressure.
 
Ice, Thank you for that clarification. Where is it that you find the difference between effectively cut off having no doors, and suitably cut off having doors with ventilation changes?
I am also trying to find where to find a clarification on what the wall construction needs to be. Aside from the typical ratings required elsewhere. Does the wall need to have any specific seals, or meet a minimum design of some sort.
 
I would say nothing special, but the intent is to not allow vapors and liquids to pass in case of discharge, so any solidish wall.....If it wanted air or vapor tight Shirley it would say so...
 
Thanks Steveray,
Most of the separation is existing masonry. It is the area that I'm screwing around with and providing a new door/small amount of sheetrock wall that I'm thinking about. just blows my mind that i can't find anything that says a little more than what exists for something that (IMO) could have a decent hazard if not done correctly.
 
Hyrax4978 said:
Where is it that you find the difference between effectively cut off having no doors, and suitably cut off having doors with ventilation changes?
Click to expand...
Actually, I didn't find it anywhere. The NEC Commentary is no help either. Given that there is nothing to validate my conclusion, please allow me to retract my previous attempt at making sense of the electrical code.

Perhaps the local AHJ can provide an answer.
 
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ICE said:
Actually, I didn't find it anywhere. The NEC Commentary is no help either. Given that there is nothing to validate my conclusion, please allow me to retract my previous attempt at making sense of the electrical code.

Perhaps the local AHJ can provide an answer.
Click to expand...
Any thoughts area always appreciated. Sometimes its someone else's interpretation that helps come to a good conclusion. I am lining up a meeting with them as we speak.
 
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