Bit of background before I start.
My Neo NAMR, build thread here was ordered with a 30amp package (AC) and a fan, LED strips inside, loading light side door and ramp door(DC). The AC has the earth (not ground) tie into the frame of the trailer. The DC, which is currently feed by the trailer (7pin) wiring as the ground (common) also connected to the frame. All the none trailer related DC share a single feed (black wire) and all DC (trailer and trailer lights (stop, turn,etc)) use the frame as a common.
NOTE: from this point on, I will only use common referring to DC and earth referring to AC.
I am puzzled as to why the AC earth and the DC common are shared. Would that not pose an issue if both AC and DC were energized at the same? I don't plan for this condition to happen often if I run the generator while the trailer is still hooked up to the TV.
The DC electrical will happen in two phases.
Phase 1: Leave everything the way it is until we have a better understanding of our desired layout but gain the ability to run the DC when not connected to the trailer (black wire is not energized unless engine is running) via either a battery or a converter hooked up the AC when shore power (or generator) is available.
Phase 2: Will probably included a PD4045 (need provision for my GFI outlet), radio, USB for charging, 12v socket, extra lights and maybe solar and maybe maybe maybe a DC fridge.
For phase 1, I see a couple of options:
Option A: Leave everything as is, do not isolate DC trailer lights and DC trailer. Connect 12v + source by tapping into feed (black) and connecting 12v - to the common (frame) would throw a fuse for good measure. This has me worried that if trailer was connected to TV and 12v source was energized at the same time bad things would happen.
Option B: Do not isolate DC trailer lights and DC trailer. Cut feed from trailer harness. Feed DC trailer from 12v source like option A. I have the same concerns as option B where the common is shared.
Options C: Isolate DC trailer from DC trailer lights by running separate common and cutting feed (black) from trailer harness. Feed 12v same way as Option A.
Option D: Same as option C but use fused distribution block and run dedicated feed for all appliances (LED strips, fan, flood lights). Run dedicated but shared common. This looks like the safest option.
Option E: Same as option D but run dedicated common wire. Note sure if necessary, doubles the work and supplies.
Any disadvantages to running a single common?
Do I plan to have LED strips, fan, side and rear floods at the same time? Not really but it could possibly happen. Do I know how the amp draw when everything is on? Not yet, I'd have to disconnect the DC ground from the trailer harness and hook it up to my multimeter while connected to the TV with it's engine running.
Thanks for your thoughts!