unfortunately, the kitchen wiring in our new condo is severely outdated. Just two circuits; one 15amp for lights and one 20amp for fridge, microwave, gas stove and oven, garbage disposal, dishwasher and countertop outlets. Surprisingly, the 20 amp only tripped once. But it's time to think about an upgrade.
We have a EMT conduit from the basement to the third floor currently with 3 circuits (2x 15amp, 1x 20amp) and one additional pair of wires for future use. I would like to add additional wires to the conduit. I researched this pretty thoroughly but it would be great to get confirmation and address some questions)
Wheatland EMT Tube, about 30' long. I think it is the 3/4'' size (outside 0.922''/ inside 0.824''). See picture with junction box below.
Current wires: 4x THWN 12 AWG, 4x THWN 14 AWG, ground wire (for 3 circuits and one unused wire pair)
Proposed additional wires for 4 additional circuits: 6x THWN 12 AWG, 2x THWN 14 AWG
Total wires: 10x THWN 12 AWG, 6x THWN 14 AWG, ground wire
Based on this calculator, the additional wires should fit in the conduit and be code compliant.
Is this calculation correct? Can I add 8 additional wires to the conduit?
Do I have to worry about the ground? I am not sure what gauge the ground wire is. But is it an issue with all the additional circuits or does the grounding work through the conduit anyways?
I will also have to use larger junction boxes in the third floor and basement. Based on my own calculation, it should be 130 cubic inches. Any suggestions for junction boxes in that size with cut-outs in the back to put the wires in the wall?