Box Fill: Do The "Tongues" Count?
#1
Box Fill: Do The "Tongues" Count?
When figuring box fill for plastic boxes do the plastic "tongues" count as clamps?
#2
Member
Ray - My guess is that they don't. My reasoning is that the tongues seem to clamp in only one direction and that some brands of plastic boxes have break out tabs instead of tongues.
Was the staple distance reduced for plastic boxes?
Was the staple distance reduced for plastic boxes?
#3
Wayne, you brought up my second question. Assuming the cable is stapled if they do count can you break them out to reduce the total box fill.
I was answering a post elsewhere about fill and wasn't sure how to answer when writing about plastic boxes.
I was answering a post elsewhere about fill and wasn't sure how to answer when writing about plastic boxes.
#4
Group Moderator
Ugh. I always assumed they did count as clamps. I never thought about the fact they only clamp in one direction.
#5
Member
I hope they don't count. If they do I probably should go back and redo a box in my kitchen - not.
My thought was always that the clamps used on metal boxes were mostly to provide a protected entrance into the box and the staples secured the cables. Since plastic boxes don't require any special protection no clamps are required.
Then again the tongues do have volume and that's what box fill calcs are all about?
My thought was always that the clamps used on metal boxes were mostly to provide a protected entrance into the box and the staples secured the cables. Since plastic boxes don't require any special protection no clamps are required.
Then again the tongues do have volume and that's what box fill calcs are all about?
#7
On plastic boxes, the manufacturer has already done the calculation and stamped both the cubic inches on the box and the number of wires allowed.
#8
The toungues on plastic multi-gang boxes are clamps. On plastic single gang boxes they are knockout tabs.
Box with no clamp stapled within 8", with a clamp within 12".
Box with no clamp stapled within 8", with a clamp within 12".
#9
Member
Plastic Box Clamps
Carlon addresses this on pages 3 and 4 of the document below. Be aware that this was written in November 2002.
http://www.carlon.com/FAQs/FAQ-ZipBoxes.pdf
http://www.carlon.com/FAQs/FAQ-ZipBoxes.pdf
#10
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Yes the internal clamps count towards box fill. Not only does the Carlon site above state so, but UL and the NFPA CMP have stated it also.
Now, does anyone actually count them, nope.
Now, does anyone actually count them, nope.
#13
Makes you wonder since the clamps are part of a listed assembly. How would UL test for proper cable retention if the clamps were removed or is it two tests?
Sure would be simpler if the volume already had an allowance for the clamp. The clamp volume is the same yet the allowance changes based on conductor size.
Sure would be simpler if the volume already had an allowance for the clamp. The clamp volume is the same yet the allowance changes based on conductor size.