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Box Volume and Box Fill - NEC Article 314.16



314.16(A) Box Volume Calculations



314.16(A) (Additions to) Box Volume Calculations


How much box volume do you want to add to your box for "plaster rings, domed covers, extention rings, and so forth, that are marked with their volume...?" boxVolumeCalculationsNotes1



314.16(A) (Reduction from) Box Volume Calculations


How much box volume do you want to subtract from your box for "securely installed barriers" that are marked with a volume? boxVolumeCalculationsNotes1_5

How many unmarked METAL barriers are there in the box? boxVolumeCalculationsNotes2

How many unmarked NON-METALLIC barriers are there in the box? boxVolumeCalculationsNotes3 boxVolumeCalculationsNotes4



314.16(B) Box Fill Calculations


314.16(B)(1) Conductor Fill


QTY AWG CONDITION MULT VOLUME SUBTOTAL
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
condition_MT volume_MT subtotal_MT
LABEL totalConductorVolume

Largest Conductor: largestAWG



314.16(B)(2) Clamp Fill


Are there any CLAMPS in the box?

clampFillCalculationsNotes in3 "clamp assembly" volume, described in the 2nd paragraph of 314.16(B)(2), to "be excluded from the box volume as marked in 314.16(A)(2)"? cableClampFillNotes



314.16(B)(3) Support Fill


Is there a STUD in the box? studFillCalculationsNotes

Is there a HICKEY in the box? hickeyFillCalculationsNotes



314.16(B)(4) Device or Equipment Fill (Single "Gang" Devices)


How many devices on a SINGLE "yoke or strap" are in the box?

What is the LARGEST conductor on device #1 ?

What is the LARGEST conductor on device #2 ?

What is the LARGEST conductor on device #3 ?

What is the LARGEST conductor on device #4 ?

What is the LARGEST conductor on device #5 ?

What is the LARGEST conductor on device #6 ?

What is the LARGEST conductor on device #7 ?

What is the LARGEST conductor on device #8 ?

What is the LARGEST conductor on device #9 ?

What is the LARGEST conductor on device #10 ?




314.16(B)(4) Device or Equipment Fill (Multiple "Gang" Devices)


How many devices, wider than 2" and covering MULTIPLE yokes or straps, are in the box?

What is the LARGEST conductor on device #1?

How many "gangs" are required to mount device #1?

What is the LARGEST conductor on device #2 ?

How many "gangs" are required to mount device #2?

What is the LARGEST conductor on device #3 ?

How many "gangs" are required to mount device #3?

What is the LARGEST conductor on device #4 ?

How many "gangs" are required to mount device #4?

What is the LARGEST conductor on device #5 ?

How many "gangs" are required to mount device #5?

What is the LARGEST conductor on device #6 ?

How many "gangs" are required to mount device #6?

What is the LARGEST conductor on device #7 ?

How many "gangs" are required to mount device #7?

What is the LARGEST conductor on device #8 ?

How many "gangs" are required to mount device #8?

What is the LARGEST conductor on device #9 ?

How many "gangs" are required to mount device #9?

What is the LARGEST conductor on device #10 ?

How many "gangs" are required to mount device #10?



314.16(B)(5) Equipment Grounding Conductor Fill


How many EQUIPMENT GROUNDING conductors are in the box?

What is the LARGEST equipment grounding conductor in the box? equipmentGroundNote






Summary of NEC Table 314.6(A) Metal Boxes
Box Trade Size Description Volume, in3
(4 x 1 ¼) round/octagonal 12.5
(4 x 1 ½) round/octagonal 15.5
(4 x 2 ⅛) round/octagonal 21.5
(4 x 1 ¼) square 18.0
(4 x 1 ½) square 21.0
(4 x 2 ⅛) square 30.3
(4-11/16 x 1 ¼) square 25.5
(4-11/16 x 2 ½) square 29.5
(4-11/16 x 2 ⅛) square 42.0
(3 x 2 x 1 ½) device 7.5
(3 x 2 x 2) device 10
(3 x 2 x 2 ¼) device 10.5
(3 x 2 x 2 ½) device 12.5
(3 x 2 x 2 ¾) device 14.0
(3 x 2 x 3 ½) device 18.0
(4 x 2 ⅛ x 1 ½) device 10.3
(4 x 2 ⅛ x 1 ⅞) device 13.0
(4 x 2 ⅛ x 2 ⅛) device 14.5
(3 ¾ x 2 x 2 ½) masonry box / gang 14.0
(3 ¾ x 2 x 3 ½) masonry box / gang 21.0
FS single cover / gang (1 ¾) 13.5
FD single cover / gang (2 ⅜) 18.0
FS multiple cover / gang (1 ¾) 18.0
FD multiple cover / gang (2 ⅜) 24.0