Box Fill Calculations

[theshockdoc]

NEC 2020 moving forward - When doing box fill calculations, how does an isolated equipment grounding conductor fit in? Is it just another EGC vs. the old interpretation of being an "additional" EGC.

 

[Dennis Alwon]

There is a change in the 2020

(5) Equipment Grounding Conductor Fill.
Where up to four equipment grounding conductors or equipment bonding jumpers enter a box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest equipment grounding conductor or equipment bonding jumper entering the box. A 1⁄4 volume allowance shall be made for each additional equipment grounding conductor or equipment bonding jumper that enters the box, based on the largest equipment grounding conductor or equipment bonding conductor.

 

[Dennis Alwon]

This was the 2017 so you can see the isolated equipment grounding conductor has been removed in 2020.

(5) Equipment Grounding Conductor Fill. Where one or
more equipment grounding conductors or equipment bonding
jumpers enter a box, a single volume allowance in accordance
with Table 314.16(B) shall be made based on the largest equipment
grounding conductor or equipment bonding jumper
present in the box. Where an additional set of equipment
grounding conductors, as permitted by 250.146(D), is present
in the box, an additional volume allowance shall be made
based on the largest equipment grounding conductor in the
additional set.