There are other versions of this question, but as each panel is distinct it requires that I ask for this particular panel. The panel is of unknown age and the house is from 1926, with remnants knob and tube wiring that were still energized when I moved in.
It's a Cutler-Hammer CH Loadcenter. I can't find a model number of any sort, like a G3040 that would mean '30 slots with 40 circuits'. There's nothing like that. It has a 200 AMP main breaker (CSR2200) and 32 full size breaker slots in it. My best guess is it's an older version of the CH32B200J Loadcenter.
Based on the lack of labeling it seems to predates the Circuit Total Limitation (CTL) rules and the 2008 NEC that dropped the hard limit on slots. So that puts in squarely into the "42" rule as best I can tell. Based on that, and using the formula that I found:
(AMPs * Number of Poles) / 10 = number of circuits
Mine: (200 * 2) = 400, and 400 / 10 = 40
So, can I have up to 40 (or 42) circuits in my 32 physical slots? Is something like the Eaton CHT2020CS (Type CH 20-Amp 1-Pole Tandem Circuit Breaker) going to just click in here without an issue?
I think that CHT is CH-Tandem, thus because the Branch Breaker CH Type column in the attached image label includes type CHT, that I am allowed to use these tandem breakers. But I don't see the little extra tabs that the CHTs expect to stabilize them (image of the bottom of my panel, red arrow).
If I CAN do this, and my panel doesn't have any restrictive design (those little tabs) that constrains the physical slot the tandem breaker goes into, is there a preference for where to place them, like at the bottom of the panel, or does it not matter at all? If they are stabilized against other breakers so they don't 'flop around' without the tab are they okay?
And finally, is this panel so old that I shouldn't stress it out? It seems mechanically okay, doesn't look like it's falling apart. Should I be looking at replacing the panel instead of testing its limits with tandem breakers? This is the start of essentially a complete rewire of the house and adding a sub panel in the garage to power some shop equipment. So I don't want to stress this panel out on step #1 if it's not made for it. I'd like to only wince once, only do this one time.
Thanks in advance! Aaron