Open Raceway from Attic to Crawlspace

[Dennis Alwon]

Dennis, The way I read the NECHandbook 300.21, fpn, and comontarys, the

intent ( regaurding the open ends of the conduit(s) ) is to maintain whatever

rating the conduits pass thru. I'm sure duct tape is not going to help that

much. I remember seeing a film on this subject, there was a shot of a 1/2"

hole thru concrete with about a 3' flame coming thru it and it sounded like

a cutting torch !! The fpn also refers to building codes.

Yes but how long a hole was it? Was it 10 foot or 4". I can see 4" but I don't know about a 10 foot piece of pipe. Perhaps there is a problem-- I just don't know. Certainly a fire can rage with flames larger than 10' but can it get enough air to travel up that pipe? Perhaps, again I don't know and I agree with you --duct tape probably won't get it as a fire stop but it would kill the air into the pipe.

 

[ultramegabob]

I wonder how long it would take for a 10' flame jetting through the PVC pipe to collapse it into a gooey heap.