Does a dashed line mean "when energized"?
I'm not well-versed in schematics, but I'm under the impression, that the dotted vertical line means "when energized"?


Dashed line means that there is a mechanical connection. Used in switches and relays in your diagrams.

In effect it means, that when the essential bus 1 relay is energized (current flows from X1 to X2) relay pulls the switches A and B into the down-position (marked with triangle).

So, when the relay is not energized, you have connection between A2 and A3, and B2 and B3. When relay is energized, there is connection between A2 and A1, and B2 and B1.

It is important to note that unless otherwise told in the drawing, they are drawn in not energized / off state.

And for the switch S70003 (Avionic Master) dashed line just indicates that it is a switch.


  Does that mean the Avionic Buses cannot be powered unless the MASTER CB is popped? 


According to the diagram you provided, avionic bus is powered whenever essential bus 1 relay and shed bus 1 relay are not energized. So if you pull the master cb, you are powering avionic bus and render avionic master switch useless.