Junction Box Grounding with 6AWG Splice
I am running power to a barn from the service panel in the garage. It will be a 40-amp service.
I will be running copper wire to a junction box inside the garage switching to aluminum.
An electrician at the supply house pointed me to the clear taps shown in the picture to splice the aluminum to copper.
My question is now I have to ground the steel junction box and how to do it.
Maybe I should return it and get a plastic box (it's 8X8) if there is such a thing.
I'm familiar with crimping on a pigtail with a ferrule with 10-14 AWG.
Must the grounding wire be the same size as the feed wires, correct? In this case 6AWG.
Bottom line what materials and techniques should I use. Regarding the tap in the picture, is it permitted to put two wires under one screw.