We are changing a 100 amp service to a 200 amp service with a new 200 amp breaker panel. I need to run a 2" pipe from the new panel to the existing part of the new house and take the wires from the 100 amp panel to a j-box. I will pull 20 20 amp circuts to the new j-box. How many grounds do I need to pull from the new panel to the j-box. Some of the old wiring has no ground.