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Box Fill Calculator

NEC 314.16 conductor count and cubic inch box fill calculation

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Box Selection

Box volume: 18 cu in

Conductors

Count each conductor that enters and terminates in the box.

6.75 inΒ³

Other Fill Items

1= 4.50 cu in

Fill Results

Total Fill Used

13.50 inΒ³

Box capacity: 18 cu in

Conductors6.75 cu in
Devices (1Γ— yoke)4.50 cu in
EGCs (all)2.25 cu in
Total13.50 / 18 cu in

βœ“ Pass β€” 4.50 cu in remaining

NEC 314.16(B) Fill Allowances

Each conductor entering & terminating1Γ— its volume
Each conductor passing through1Γ— its volume
All EGCs combined1Γ— largest conductor
Each device yoke / strap2Γ— largest conductor
All internal clamps combined1Γ— largest conductor
Isolated grounding conductors1Γ— each its own volume
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