NFPA Definition of "Structure" and Ruling

[milwaukeebob]

Hello,
I have a question regarding the NFPA definition of a structure. I know in the 2017 Code the definition of a "Structure" was changed. The definition now states "That which is built or constructed, other than equipment. (CMP-1)". They added the reference to equipment for clarity.

I am working on the construction of a new small power plant. Part of the installed design includes a back-up mobile gas generator which has a rating of ~1.5MW. This is a packaged generator that is in a very large movable ~35' container with a hard flex-piped connection to a natural gas supply and a hard-wired electrical connection to the facility via cable tray. This is a pre-packaged unit built off-site but then hard-piped/wired into the facility. Would NFPA rule this a "Structure"?

The same question applies to the hard flex-piped connection and associated gas piping stub-up coming out of the ground and cable-tray network that was built on site. Would NFPA rules these "Structures".

Thanks for any guidance on this.

MB

 

[cdafd]

Is this located in the USA?

I would call it a piece of equipment,,, even before the code change

Some reading::

https://www.electricallicenserenewa...ation-Courses/NEC-Content.php?sectionID=211.0

 

[milwaukeebob]

Thanks cdafd. Appreciate the feedback. Yes the project is in the U.S. Also, thanks for the link...I've seen this before.

My question is ultimately related to NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants…) Chapter 5 (General Plant Design) section 5.1.4 (Outdoor Oil Filled Transformers) and associated table 5.1.4.3 defines the separation criteria for oil filled transformers “from adjacent 'structures' and from each other by firewalls, spatial separation, or other approved means for the purpose of limiting the damage and potential spread of fire from a transformer failure”.

This natural gas powered back-up mobile generator is well within the "separation criteria" as defined by NFPA 850. My concern is not only collateral damage to the generator because of a large transformer fire but also the proximity to natural gas source. My experience suggests much greater separation between a large transformer and other components of the facility like this.

 

[cdafd]

Codes are normally minimum requirement,, can always go beyond

Anything in 850 for separation of oil transformers to fuel fired equipment??

If so meet or exceed that, if not you can always advise for greater distance,,, or build a wall???

Gas should be mostly underground. Add another above ground shut off valve, away from the transformers

 

[milwaukeebob]

Thanks cdafd. Understood. I need to take a deeper dive into NFPA 850. Yes - the building of a wall (or in this case extending one) would be the correct choice. Unfortunately, there's some challenges associated with that. Again, I appreciate all your feedback.

 

[ProSafPlant1]

NFPA Glossary of terms:

https://www.nfpa.org/~/media/Files/Codes and standards/Glossary of terms/glossary_of_terms_2021.ashx

I would say the container meets the definition of a "building", which is a subset of a "structure".