I am replacing an undersized 35 amp main lug, so the panel, conductors and breaker in the main panel are all being replaced.
The new panel will be 125 amp rated, the new conductors will be #3 THHN, with an ampacity rating of 115, which will be protected by a 100 amp 2 pole breaker in the main panel.
What size does the grounding conductor leading back to the main panel need to be?
This calculator seems to indicate I need a #8 copper conductor, but I'm not sure this is the correct table for me to use.
This project must be done to code for Arapahoe county Colorado (2017 NEC)