# Subpanel capacity

I will be installing a 125A subpanel using a #2 Cu THHN via 2" x 3"(L) conduit secured with four 2-in conduit locknuts (inside and outside of panels). The sub-panel shut-off will be a Q2125 125-Amp Double Pole Type QP.

The first photo shows the current configuration with a small, 8 circuit subpanel that will be replaced with a 20/20 125A box. I will further be adding 40A 240V (oven/micro combo), and 50A 240V (induction cooktop), as well as two 20A circuits, one for a dishwasher and another perhaps for an island outlet with beverage fridge (no sink or stove on the island).

I am trying to calculate the maximum capacity I can put on this subpanel, and whether I can just add the new circuits I mentioned above, or whether I need to rebalance with the main panel.

• Can you provide us information about what the GFCI circuit serves, as well as the wattage of the cooktop and the oven/microwave combo? Also, why are you using copper for a 125A feeder? Commented Sep 3, 2020 at 22:53
• @ThreePhaseEel, yes, the GFCI is for kitchen counter but after posting I realized that I already have plenty of GFCI circuits in there that I can use (4x). I added a diagram in the original question of what the two panels look like now (except sub is currently is small 8 circuit). I will be adding a 40A 240V (oven), and 50A 240V (induction cooktop), as well as 1 or two 20A circuits one for a dishwasher and another perhaps for an island (no sink or stove on the island). I have a new 125A 2020/panel that will be replacing the small one. Commented Sep 4, 2020 at 18:10
• @ThreePhaseEel Edited the original question to better reflect what I am trying to do. Commented Sep 4, 2020 at 18:48
• We don’t worry about double pole breakers when balancing by load, on the single pole you try to distribute the total on the odd breakers with the total on the even breakers for example we know 20’s can Cary more if they are all on even breakers L2 would normally be loaded heavier. Without the connected loads that would be your best guess at balancing getting as close to even numbers of 15 or 20 on the odd breakers as the even breakers. Pros use amp clamp meters and Measure with different things turned on to balance the loads. Commented Sep 4, 2020 at 19:37
• That is reasonable and probably what I would do small loads are easier to to move around. Commented Sep 4, 2020 at 20:39