I've often wondered why so many resi EC's (around me at least) use 30 circuit loadcenters with stabs allowing twin breakers, then use the twins to fill the last 10 spaces to get all their circuits in. The loadcenter isn't that much cheaper than a 40 circuit, and the use of twins run their cost over what a 40 with standard breakers would be. One day I'll get brave and ask one of them at the supply house why. I mean really, just how cheap and bottom line can we get?
We also often trace under-used circuits down to tie together, so that we have a available space for an added 20 amp circuit. It's either that, or the sub-panel route, which takes finding TWO spaces just to add the breaker feeding the sub.
