Updating a house to 100 amps

(Bus bars are the energized metal bars that the circuit breakers connect to.) These panels are often crowded and no longer have ample space to accommodate modern wiring requirements.

Most of the time I find myself recommending to my buyers that they upgrade these panels.

The next picture is of a split bus panel with the cover off—notice how much it looks like the sub-panel picture above (well except for neatness)?

The blue dotted lines are where the power coming into the panel attach to the bus bars.

To recap: In a typical split bus panel found in a residence there will be provision for “6” double pole breakers (or less)—one of which is the disconnect for all the breakers located below the 6 double pole breaker locations.