Box Fill worksheet

1. Volume required: 19.25 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $5\times 2.25$$=11.25\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 8 AWG allowance

   $1\times 3$$=3\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 2.5$$=5\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $11.25+3+5$$=19.25\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $13-19.25$$=\mathrm{-6.25}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{19.25}{13}\times 100$$=\mathrm{148.08\%}$

2. Volume required: 26.95 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $4\times 2.25+3\times 1.4$$=13.2\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 8 AWG allowance

   $1\times 3$$=3\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 2$$=4\text{\hspace{0.17em}in³}$

4. Fixture studs and hickeys: one allowance each at the largest wire (NEC 314.16(B)(3))

   $3\times 2.25$$=6.75\text{\hspace{0.17em}in³}$

5. Add up every item to get the total volume the box must have

   $13.2+3+4+6.75$$=26.95\text{\hspace{0.17em}in³}$

6. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $18-26.95$$=\mathrm{-8.95}\text{\hspace{0.17em}in³}$

7. Share of the box volume used, which shows how crowded the box will be

   $\frac{26.95}{18}\times 100$$=\mathrm{149.72\%}$

3. Volume required: 28.25 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $5\times 2.25$$=11.25\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for all of them (NEC 314.16(B)(5), editions before 2020), at the 6 AWG allowance

   $1\times 5$$=5\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 2\times 3$$=12\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $11.25+5+12$$=28.25\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $14-28.25$$=\mathrm{-14.25}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{28.25}{14}\times 100$$=\mathrm{201.79\%}$

4. Volume required: 31.5 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $4\times 2.25+2\times 5$$=19\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for all of them (NEC 314.16(B)(5), editions before 2020), at the 10 AWG allowance

   $1\times 2.5$$=2.5\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 5$$=10\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $19+2.5+10$$=31.5\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $18-31.5$$=\mathrm{-13.5}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{31.5}{18}\times 100$$=\mathrm{175\%}$

5. Volume required: 29 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $1\times 2+4\times 2.25+1\times 3$$=14\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for all of them (NEC 314.16(B)(5), editions before 2020), at the 6 AWG allowance

   $1\times 5$$=5\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 5$$=10\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $14+5+10$$=29\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $24-29$$=\mathrm{-5}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{29}{24}\times 100$$=\mathrm{120.83\%}$

6. Volume required: 33.2 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $1\times 2+5\times 2.25+1\times 2.5+1\times 2.2$$=17.95\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 12 AWG allowance

   $1\times 2.25$$=2.25\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 2\times 2$$=8\text{\hspace{0.17em}in³}$

4. Fixture studs and hickeys: one allowance each at the largest wire (NEC 314.16(B)(3))

   $2\times 2.5$$=5\text{\hspace{0.17em}in³}$

5. Add up every item to get the total volume the box must have

   $17.95+2.25+8+5$$=33.2\text{\hspace{0.17em}in³}$

6. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $15-33.2$$=\mathrm{-18.2}\text{\hspace{0.17em}in³}$

7. Share of the box volume used, which shows how crowded the box will be

   $\frac{33.2}{15}\times 100$$=\mathrm{221.33\%}$

7. Volume required: 28.5 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $4\times 2.25+1\times 5$$=14\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for all of them (NEC 314.16(B)(5), editions before 2020), at the 6 AWG allowance

   $1\times 5$$=5\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 2.25$$=4.5\text{\hspace{0.17em}in³}$

4. Fixture studs and hickeys: one allowance each at the largest wire (NEC 314.16(B)(3))

   $1\times 5$$=5\text{\hspace{0.17em}in³}$

5. Add up every item to get the total volume the box must have

   $14+5+4.5+5$$=28.5\text{\hspace{0.17em}in³}$

6. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $16-28.5$$=\mathrm{-12.5}\text{\hspace{0.17em}in³}$

7. Share of the box volume used, which shows how crowded the box will be

   $\frac{28.5}{16}\times 100$$=\mathrm{178.13\%}$

8. Volume required: 18.75 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $5\times 2.25$$=11.25\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 8 AWG allowance

   $1\times 3$$=3\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 2.25$$=4.5\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $11.25+3+4.5$$=18.75\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $15-18.75$$=\mathrm{-3.75}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{18.75}{15}\times 100$$=\mathrm{125\%}$

9. Volume required: 38.25 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $5\times 2.25+3\times 5$$=26.25\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 14 AWG allowance

   $1\times 2$$=2\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 5$$=10\text{\hspace{0.17em}in³}$

4. Add up every item to get the total volume the box must have

   $26.25+2+10$$=38.25\text{\hspace{0.17em}in³}$

5. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $15-38.25$$=\mathrm{-23.25}\text{\hspace{0.17em}in³}$

6. Share of the box volume used, which shows how crowded the box will be

   $\frac{38.25}{15}\times 100$$=\mathrm{255\%}$

10. Volume required: 58.75 in³

1. Conductors: each counts once at the allowance for its size (NEC 314.16(B)(1))

   $2\times 2+5\times 2.25+1\times 2.5+3\times 5$$=32.75\text{\hspace{0.17em}in³}$

2. Grounding wires: one allowance for up to four, plus a quarter for each extra (NEC 314.16(B)(5), 2020 and later), at the 6 AWG allowance

   $1\times 5$$=5\text{\hspace{0.17em}in³}$

3. Devices: two allowances per yoke or strap, at the largest wire connected to it (NEC 314.16(B)(4))

   $2\times 1\times 3$$=6\text{\hspace{0.17em}in³}$

4. Fixture studs and hickeys: one allowance each at the largest wire (NEC 314.16(B)(3))

   $3\times 5$$=15\text{\hspace{0.17em}in³}$

5. Add up every item to get the total volume the box must have

   $32.75+5+6+15$$=58.75\text{\hspace{0.17em}in³}$

6. Subtract the required volume from the space available: there is a shortfall, so the box is too small

   $16-58.75$$=\mathrm{-42.75}\text{\hspace{0.17em}in³}$

7. Share of the box volume used, which shows how crowded the box will be

   $\frac{58.75}{16}\times 100$$=\mathrm{367.19\%}$