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Question regarding generator placement for NFPA 37

Question asked by bruehlt on Aug 3, 2019
Latest reply on Sep 29, 2020 by brianbaughman

Hi - I am looking to install a whole home standby generator (Cummins RS22) and I've read the forums here about Section 4.1.4 of NFPA 37, but there are a couple of items that are not clear to me.  The text states a 5 foot rule.  Is the 5 foot rule measured directly from the opening or combustible wall?  For example - if the opening is 10 feet off of the ground, would I measure 5 feet from the wall, or 5 feet directly from the bottom of the opening?


Also - what is considered combustible regarding a wall?  My house is concrete block.  The height of the soffit is about 8 feet off of the ground, give or take.  Is the concrete block wall considered combustible or not?  What about the soffit?  It appears there is a lot of leeway for the local authority to make the call in some cases.


To further the confusion, the manual for the Cummins states 5 feet from the exhaust of the generator from any combustible wall or opening.


I've attached a photo of the location I am looking at.  The distance to from the wall to the farthest flag is about 125 inches (12 feet).  The window on the left opens, the window on the right is fixed and does not open.  The generator itself is 71" in length, 34" wide, and 45" high.  I'd like to place the exhaust side out towards the lawn, but place it as close to both walls as I can by code standards.  So far I've had 3 different companies come out and it seems they all have differing answers about how they would install.