I would like to use flexible metal conduit as a chase through which to pull NM cable. My question is, does the 2008 NEC permit me to do this?
Assuming anyone is tempted to offer an answer, it may help to know some further details, so please read on.
I am in the process of roughing in outlet boxes in the exterior walls of the first floor of a house that is undergoing renovation. The boxes are 4-square steel, conduit type boxes. The finishes on the first floor walls have been removed. The construction is conventional wood frame. The first floor sits over a full basement. The basement is unfinished and will most likely remain so after remodeling is done. The outlet boxes (on the first floor) sit approximately 12 inches about the finished floor.
I would like to run short lengths of empty flex conduit (?" or ?", depending on fill requirements) from one or more of these boxes through the bottom plate and down into the joist bays in ceiling of the basement. From the basement, and through the flex conduit, my plan would be to later pull NM cable to supply the boxes.
Where the NM cable is exposed in the basement, I would be stapling and supporting it according to Code (as best as I can understand it!). Where the cable enters the flex (at the basement end), I would like to use some kind of flex-to-NM connector that would clamp onto the NM cable and prevent it from sliding freely back and forth through the flex and possibly being abraded if it were later disturbed. I would be anchoring the flex to the framing in close proximity to the boxes and where it passes up through the subfloor and bottom plate. If there is no such flex-to-NM connector, I suppose I could connect the flex to a (very) short length of EMT, then pull the NM cable into the EMT. I have seen NM-to-EMT and EMT-to-flex and connectors.
From reviewing the Code and many helpful posts on this site, I understand that pulling NM through conduit is (now) permitted in order to protect it from physical damage. But is it permitted to use flex as a "chase" for NM in at least short runs like this?
Why do I want to do this, I will probably be asked? There are a lot of unknowns yet to be resolved. I do not know yet how many circuits I will be running from the first floor and into the basement, from which boxes it will be best to make the home runs to the main panel, or what paths I will use to get them there. I would like to have the option though of using NM cable when the time comes. I would also like to avoid cluttering up the basement ceiling with a lot of flex and junction boxes. Lastly, installing chases at key boxes would give me the flexibility later to use NM cable to supply the boxes or to splice on more flex and pull in conductors in the conventional way (and, yes, clutter up the ceiling with a bunch conduit and boxes!).
Again, I am using the 2008 NEC. Any help would be greatly appreciated.
Thank you in advance.
-ENeophyte
Assuming anyone is tempted to offer an answer, it may help to know some further details, so please read on.
I am in the process of roughing in outlet boxes in the exterior walls of the first floor of a house that is undergoing renovation. The boxes are 4-square steel, conduit type boxes. The finishes on the first floor walls have been removed. The construction is conventional wood frame. The first floor sits over a full basement. The basement is unfinished and will most likely remain so after remodeling is done. The outlet boxes (on the first floor) sit approximately 12 inches about the finished floor.
I would like to run short lengths of empty flex conduit (?" or ?", depending on fill requirements) from one or more of these boxes through the bottom plate and down into the joist bays in ceiling of the basement. From the basement, and through the flex conduit, my plan would be to later pull NM cable to supply the boxes.
Where the NM cable is exposed in the basement, I would be stapling and supporting it according to Code (as best as I can understand it!). Where the cable enters the flex (at the basement end), I would like to use some kind of flex-to-NM connector that would clamp onto the NM cable and prevent it from sliding freely back and forth through the flex and possibly being abraded if it were later disturbed. I would be anchoring the flex to the framing in close proximity to the boxes and where it passes up through the subfloor and bottom plate. If there is no such flex-to-NM connector, I suppose I could connect the flex to a (very) short length of EMT, then pull the NM cable into the EMT. I have seen NM-to-EMT and EMT-to-flex and connectors.
From reviewing the Code and many helpful posts on this site, I understand that pulling NM through conduit is (now) permitted in order to protect it from physical damage. But is it permitted to use flex as a "chase" for NM in at least short runs like this?
Why do I want to do this, I will probably be asked? There are a lot of unknowns yet to be resolved. I do not know yet how many circuits I will be running from the first floor and into the basement, from which boxes it will be best to make the home runs to the main panel, or what paths I will use to get them there. I would like to have the option though of using NM cable when the time comes. I would also like to avoid cluttering up the basement ceiling with a lot of flex and junction boxes. Lastly, installing chases at key boxes would give me the flexibility later to use NM cable to supply the boxes or to splice on more flex and pull in conductors in the conventional way (and, yes, clutter up the ceiling with a bunch conduit and boxes!).
Again, I am using the 2008 NEC. Any help would be greatly appreciated.
Thank you in advance.
-ENeophyte
