Master switch - single point of failure?

[lithium366]

As I am planning my avionics upgrade (Dynon) in a 66E I am thinking of the situation when both standby instrument (EFIS) and PFD can turn off if both poles (Battery and generator) in a single master switch fail. Perhaps I am concerned with both poles being in a single enclosure. Thoughts?

[Ragsf15e]

You’ll have a battery backup as well, right?

But yes, there are lots of different “single points” of failure.  

If you are getting rid of the vacuum system I definitely recommend thinking through electrical failure emergencies and what will happen.  Then make sure you have a solid attitude backup that won’t be affected (battery backup) and is always visible.  
 

I have 2xg5s and test their batteries.  Having an ipad up with a portable ahrs is another option.

[Yetti]

I think you will find that they suggest one of the screen is turned on by the Master switch so you have engine instruments when engine starts.   Then the other screen(s) can come on with the Com Master.  The EMS box and the other things on the DB9 network are supplied with 5v from the Screen.   So you will want to make sure the 5v going to the Engine bay comes from the screen that is turned on with the master.

[Yetti]

As far as failure there are batteries on each screen you install and then a battery in the D10A which is your back up should the HDX go inop.