It was common practice for Bell companies to lay their cable directly into the slab in the 1960's. Be really careful when chipping out the concrete because that cable loops back out to other outlets in the apartment. If it's not long enough to reach the wall, which appears to be the case, you might want to consider some kind of floor box to contain the splice.
As for the horizontal panel, my guess is that he didn't think that it was wide enough to contain the existing conduits in the bottom. As for the question about tandem breakers, that's all up to the panel's manufacturer. The diagram should indicate which poles are rated for tandems and should have the CTL notching. From the diagram, it appears that all pole spaces are approved for tandem breakers.
Last edited by EV607797; 03/06/08 11:57 AM.
