314.17(C) What does this mean? Part 2

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Little Bill

Little Bill

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Since Rob closed his thread, I'm opening up a part 2 for further discussion.
Do the plastic grips inside a plastic box count as a cable clamp? If not, how do we use more than a single gang box and be code compliant?:?
 
Little Bill said:
Since Rob closed his thread, I'm opening up a part 2 for further discussion.
Do the plastic grips inside a plastic box count as a cable clamp? If not, how do we use more than a single gang box and be code compliant?:?
Click to expand...

Of course they count as a clamp. That is why you can use a 2 gang, etc box. I have heard inspectors turn down jobs when the electricians pry the clamp so far that they do not grip. This is why I don't like certain boxes. The clamps don't seem to hold whereas p&S boxes have very good clamps.
 
What kind of clamps are you referring to? The ones in these boxes do not count towards conductor fill.

B232A-UPC.jpg


101C16297EDC484BBDB97B7780C3394A.ashx
 
Dennis Alwon said:
Of course they count as a clamp. That is why you can use a 2 gang, etc box. I have heard inspectors turn down jobs when the electricians pry the clamp so far that they do not grip. This is why I don't like certain boxes. The clamps don't seem to hold whereas p&S boxes have very good clamps.
Click to expand...

I have found that where you can, that stripping the sheathing before I put it in the box and use the wire to open the clamp, works better than opening the clamp with a screwdriver. The screwdriver (or it's user) sometimes opens the clamp too far and it doesn't hold good then. But you're right, some of the blue boxes have weak clamps no matter how you open them. I think the "super Blue" ones have a better clamp than the regular ones.
 
Little Bill said:
I have found that where you can, that stripping the sheathing before I put it in the box and use the wire to open the clamp, works better than opening the clamp with a screwdriver. But you're right, some of the blue boxes have weak clamps no matter how you open them. I think the "super Blue" ones have a better clamp than the regular ones.
Click to expand...

I always use super blues from CARLON because of they rigidity and their clamps do not break off that easily. for me it is easier to strip the jacket then
install the cable in the box.
 
I do strip my NM before I put it in the box. Always have done that.

I wasn't taking about box fill either. I do not like the blue carlon box clamps at all.

I don't count them either-- if you look inside the box it tells you how many wires are allowed. If you calculate it without clamps it comes to the same.
 
Dennis Alwon said:
I don't count them either-- if you look inside the box it tells you how many wires are allowed. If you calculate it without clamps it comes to the same.
Click to expand...

Dennis, I'd like to see something definitive about that. AFAIK, you should count the clamps. Since the factory does not know what size conductors the end user will install in the box, it makes sense that the cubic inch rating and the conductor numbers would match - they wouldn't know what to value their clamps at, at the factory.
 
I never count them either and I thought I remember a long decision about it quite a while ago. I think it had something to do with the clamp being integral to the wall of the box, if the clamp is molded as part of the box wall can it said to be "inside" the box. ???
IDK. Would like some clarification.

Also I too always strip the sheath and jam the wires first into the clamp and never felt they were difficult to use.
 
__

Hmmmm......


_____________________________________________________________
9-41 Log #3910 NEC-P09 Final Action: Reject
(314.16(B)(2))
_______________________________________________________________
Submitter: Andrew Darois, David Kramer Electric
Recommendation: Revise text as follows:
Clamps in molded plastic boxes that are built in shall not be counted.
Substantiation: These boxes are made with the clamps. Their volume is
calculated taking into account the clamps. Some inspectors will have you count
the clamps.
Panel Meeting Action: Reject
Panel Statement: The submitter?s substantiation is inaccurate. The total cubic
inches for nonmetallic boxes is determined with the internal cable clamps
removed prior to the determination by the third-party testing agency. The
requirement to take a single volume allowance for cable clamps is based on the
fact that the clamps reduce the usable volume in the box when the box is wired.
A molded clamp will reduce the usable volume when it is employed.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
_______________________________________________________________
 
jumper said:
__

Hmmmm......


_____________________________________________________________
9-41 Log #3910 NEC-P09 Final Action: Reject
(314.16(B)(2))
_______________________________________________________________
Submitter: Andrew Darois, David Kramer Electric
Recommendation: Revise text as follows:
Clamps in molded plastic boxes that are built in shall not be counted.
Substantiation: These boxes are made with the clamps. Their volume is
calculated taking into account the clamps. Some inspectors will have you count
the clamps.
Panel Meeting Action: Reject
Panel Statement: The submitter’s substantiation is inaccurate. The total cubic
inches for nonmetallic boxes is determined with the internal cable clamps
removed prior to the determination by the third-party testing agency. The
requirement to take a single volume allowance for cable clamps is based on the
fact that the clamps reduce the usable volume in the box when the box is wired.
A molded clamp will reduce the usable volume when it is employed.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
_______________________________________________________________
Click to expand...

According to that panel comment they're speaking specifically about boxes where the clamps can be removed.
 
infinity said:
According to that panel comment they're speaking specifically about boxes where the clamps can be removed.
Click to expand...

Mebbe.

Here is what Carlon says:

The volume inside an outlet box does not include any deductions for integral
clamps. The clamps are removed from the box when the volume is determined
by UL. Therefore a single deduction in the NEC is required for the space the
clamps take up inside the box. A B520A is 18 cubic inches after the clamp
deduction for #14 wire.
This procedure was determined by IAEI and UL. Not everybody agrees to this.

http://www.carlon.com/FAQs/FAQ-ZipBoxes.pdf

B520A

roundbox.jpg
 
jumper said:
Mebbe.

Here is what Carlon says:

The volume inside an outlet box does not include any deductions for integral
clamps. The clamps are removed from the box when the volume is determined
by UL. Therefore a single deduction in the NEC is required for the space the
clamps take up inside the box. A B520A is 18 cubic inches after the clamp
deduction for #14 wire.
This procedure was determined by IAEI and UL. Not everybody agrees to this.

http://www.carlon.com/FAQs/FAQ-ZipBoxes.pdf

B520A

roundbox.jpg
Click to expand...

Are you sure that what you've posted is for the box in the photo? How would you remove those clamps?
 
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