Purge/Pressurization - power supply disconnect location

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nhee2

Senior Member
Location
NH
A client is adding a purge to an existing cabinet in a Class I, Div 2 location - intent is for the system to provide Type Z protection.

In a manufacturer document (Hoffmann/nvent) (https://hoffman.nvent.com/sites/g/files/hdkjer316/files/acquiadam/2020-12/87571946.pdf) I found on-line it says that the breaker/switch providing power to the protected enclosure must be located within 50 feet of the protected enclosure(s).

I am looking through NFPA 496 and the 2020 NEC article 500, and I do not see this as a requirement of the code - is it just a mfr specific installation requirement? Or am I not looking hard enough in the code? I note the manufacturer document is currently on their website, but is pretty old, referencing the 1999 NEC.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
for the most part disconnecting means are required to be "within sight".

from article 100

In Sight From (Within Sight From, Within Sight). Where this
Code specifies that one equipment shall be “in sight from,”
“within sight from,” or “within sight of,” and so forth, another
equipment, the specified equipment is to be visible and not
more than 15 m (50 ft) distant from the other.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
A client is adding a purge to an existing cabinet in a Class I, Div 2 location - intent is for the system to provide Type Z protection.

In a manufacturer document (Hoffmann/nvent) (https://hoffman.nvent.com/sites/g/files/hdkjer316/files/acquiadam/2020-12/87571946.pdf) I found on-line it says that the breaker/switch providing power to the protected enclosure must be located within 50 feet of the protected enclosure(s).

I am looking through NFPA 496 and the 2020 NEC article 500, and I do not see this as a requirement of the code - is it just a mfr specific installation requirement? Or am I not looking hard enough in the code? I note the manufacturer document is currently on their website, but is pretty old, referencing the 1999 NEC.
This, excerpted from the manual, emphasis added:

The Manual’s parameters encompass a combination of both National Fire Protection Association (NFPA) requirements and Pepperl+Fuchs, Inc. requirements. Pepperl+Fuchs therefore acknowledges the use of NFPA 496 as a guideline, that we have enhanced certain NFPA requirements and that additional information has been compiled to complete this document. The Manual is intended as a complete guide and must be considered, unless specifically stated otherwise, that all directives contained herein are requirements for safe, practical and efficient use of this product.

Instructions are part of the system's listing and have to be followed.
 

nhee2

Senior Member
Location
NH
for the most part disconnecting means are required to be "within sight".

from article 100
Thanks, agreed, although I don't see a requirement for this particular panel (in Article 409, maybe 508A requires it) to have a disconnect (not feeding motor loads). It's required to have OCPD by 409.21 which it would have had.

Instructions are part of the system's listing and have to be followed.
Agreed, mfr instructions will be followed, just trying to verify whether it was a code requirement or above and beyond.

Thanks
 
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