Two districts set up.
The 2nd CB board was installed for Blocks B-5,6 and all worked great.
I had several DCC engines on the layout including one in District 2.
An induced short in district 1 had no affect on district 2 or the other DCC engines and the command station did not 'beep', which indicates a short, thus the CB is "doing it's job".
The reverse was done shorting out district 2 with the same results.
I can now order 6 more onguard CB's to cover the remaining districts.
I soldered some LED's to the CB to indicate power/short status.