Carlon single gang box claims it holds 4 #12/2's AND a receptacle, but wait...

[Jerramundi]

90.1(A) Practical Safeguarding . . . it's not practical to sweat 0.25 in³? : - )

Cheers, Wayne

Fair, but extremely open to interpretation. What's to say I then can't argue that it's not practical to sweat a complete fill volume of 2 cu in?

 

[480sparky]

Now that I think about it (and correct me if I'm wrong)...

There's NOTHING in the NEC that allows us to go by the # OF CONDUCTORS as allowed by the manufacturer......

110.3.

 

[Dennis Alwon]

Is this not a calculation?

220.5 Calculations.
(A) Voltages. Unless other voltages are specified, for purposes
of calculating branch-circuit and feeder loads, nominal system
voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480,
600Y/347, and 600 volts shall be used.
(B) Fractions of an Ampere. Calculations shall be permitted
to be rounded to the nearest whole ampere, with decimal fractions
smaller than 0.5 dropped.

 

[Jerramundi]

Is this not a calculation?

Yes. Well done. Good to see a code based substantiation for rounding.
But do I dare point out it's for... ampere based calculations? *ducks behind nearest solid object*

Why do I foresee a debate about volume being relevant to amperage, lol.

 

[Dennis Alwon]

Yes. Well done. Good to see a code based substantiation for rounding.
But do I dare point out it's for... ampere based calculations? *ducks behind nearest solid object*

Why do I foresee a debate about volume being relevant to amperage, lol.

That would actually be a good thing to propose for 2023
-- which may be too late... Usually it is NOV....

It was over in Sept 10, 2020-- darn I missed it this year....LOL

 

[LarryFine]

*ducks behind nearest solid object*

Here ya' go:

 

[don_resqcapt19]

There are a couple of specific "rounding" rules, but none actually apply to box fill calculations. As currently written, the box fill rules are absolute with no rounding permitted.

 

[don_resqcapt19]

110.3.

110.3(B) cannot change a code rule.

 

[James L]

https://rexel-cdn.com/Products/AlliedMoulded/P-241QT.pdf?i=B24CAAEA-A8D2-4517-B1D2-FBA684237154

https://rexel-cdn.com/Products/AlliedMoulded/SB-1.pdf?i=73C9BB20-ACC9-4D31-BC5E-D1B73EE9B7BD

Switch to these and you can get a couple more Cu.in

Would like a single gang at 26 or 28 cu.in have not found any

Almost forgot about this 30cu.in. option

Carlon 1-Gang 30 cu. in. PVC New Work Electrical Box RD30-6R - The Home Depot

The 1-Gang New-Work Dryer-Outlet Box is intended for use as an outlet box for dryers in new work applications . The outlet box is intended for indoor use and has a non-metallic, plastic construction. This item is fire rated and UL listed for safety.

www.homedepot.com

 

[480sparky]

110.3(B) cannot change a code rule.

I never said it could.

 

[Dennis Alwon]

There are a couple of specific "rounding" rules, but none actually apply to box fill calculations. As currently written, the box fill rules are absolute with no rounding permitted.

Agreed but it is there for amps and it is there for pipe fill (.8). I bet it is just an oversite

 

[don_resqcapt19]

Agreed but it is there for amps and it is there for pipe fill (.8). I bet it is just an oversite

I am not so sure. UL 514 permits the marked volume to be rounded to the nearest 1/4 cubic inch. Not sure there is an intent to permit rounding for conductors. If you can round 0.51 to one, that is a much larger rounding in cubic inches than what is permitted for the volume marking on the box.

Even if rounding is intended to be permitted for box fill, would you use 0.5 like in 220.5 or 0.8 as in Chapter 9 notes?

 

[Dennis Alwon]

I am not so sure. UL 514 permits the marked volume to be rounded to the nearest 1/4 cubic inch. Not sure there is an intent to permit rounding for conductors. If you can round 0.51 to one, that is a much larger rounding in cubic inches than what is permitted for the volume marking on the box.

Even if rounding is intended to be permitted for box fill, would you use 0.5 like in 220.5 or 0.8 as in Chapter 9 notes?

IMO, it would .8 but that is all it is--my opinion-- not worth much. I wish I didn't miss the proposal this go around... Oh well if I make it to next one I'll try and remember

 

[HEYDOG]

Carlon B125AB
these boxes are pretty cool:
>single gang with steel stud mount or wood stud nails
>convertible from new construction to remodeler box
>internal provisions for drywall screw mounting - both vertically and horizontally
>best of all, the box nub is set to 1/2" unlike other carlon boxes that are set at 3/8"
>claims wire volume for 11 #12's. That's ground shattering for a single gang box i feel

Inside the box is stamped this:
24.5 cubic inches
12 #14
11 #12
10 #10

So my understanding of conduit wire fill and box wire fill is that the .8 remainder rule of rounding up doesn't apply to boxes, only conduits. Correct me if I'm wrong or something, but how can the manufacturer divide 2.25 (fill allowance for #12) into 24.5 (box cubic volume) and not get 10.8? Wouldn't you need to drop the .8 and be left with 10 #12's; not the manufacturer's claim of 11 #12's?

Looking at the 12 #14 shows that the remainder of .25 correctly got dropped. But looking at the 10 #10 shows the same .8 again got rounded up. Does anyone have insight to what is going on here?

If you go to Carlon Website. It say’s that the second and third number...in the catalog number....designates the cubic inches. Thus 25 is 25 cubic inches. I realize that it is stamped 24.5.

 

[HEYDOG]

https://carlonsales.com/techinfo/brochures/electrical/Zip%20Boxes_2B1.pdf

 

[don_resqcapt19]

If you go to Carlon Website. It say’s that the second and third number...in the catalog number....designates the cubic inches. Thus 25 is 25 cubic inches. I realize that it is stamped 24.5.

Unless it is one of the standard boxes with the volume shown in the code itself, the stamped marking on the box is what applies. Nothing in a catalog or other document changes that.

 

[HEYDOG]

Okay! Which stamp 24.5 cubic inches or 11 # 12 conductors. ?

 

[nizak]

Okay! Which stamp 24.5 cubic inches or 11 # 12 conductors. ?

Just think of the millions of homes and businesses built in the 60’s and 70’s that have 3 #12 NM cables and a device and 2 red wirenuts in a 3”x2” x2 metal box.

Or the 3 1/2” x 1 1/2”metal octagon ceiling box with 4/5 #14 black cloth romex wires and a fixture hickey.

Amazes me how they ever got the wires in there.

 

[don_resqcapt19]

Okay! Which stamp 24.5 cubic inches or 11 # 12 conductors. ?

The UL standard requires the volume to be marked on the inside of the box and the code requires that you use that volume for the wire fill calculations.

 

[LarryFine]

Or the 3 1/2” x 1 1/2”metal octagon ceiling box with 4/5 #14 black cloth romex wires and a fixture hickey.

Amazes me how they ever got the wires in there.

Or BX-wired homes where every receptacle in the room was fed from the ceiling box, along with the feed in and out, and a switch leg (or two). Add to that soldered joints with rubber and friction tapes.

Sometimes, there seemed to be no empty space left, as if the wires had been hammered into place.