Is there any way you can get a shock from the chassis if it is not grounded?
You can use the deck mount as a power supply with the neg DC output going to the neg DC input of whatever is being powered. That thing being powered not being a battery that is "neg grounded". EG an inverter.
The chassis ground lug on the outside is where on the inside the green ground wire of the 120v input goes while the white and black go to the board (the black has a glass fuse there)
The RV is one giant "multiple grounds" collection, so that can't be a no-no. EG:
There was a note years back about using a deck mount instead of the "lower portion" (converter part) of a power centre. It said the lower portion in its metal case is touching the metal case of the power centre, which in turn is grounded to the RV frame via the bare copper wire of the 120v shore cord input that has its black to the Main breaker and white to the N buss. The note said the deck mount would not be touching, so it needed its own chassis ground. I don't know why it would need that.
In that case the lower portion converter 120v input did not have a green wire, just the white and black (eg 7300 converter) The DC fuse panel has 12v negs that also go to the frame eventually. You can put your meter on a pos lug and the neg lug and see 12v or you can put the neg lead on the metal power centre metal chassis instead of the DC panel neg lug and still see the 12v
The RV frame shares being the "ground" for 120v and 12v and there can be complications with some inverters which have GFCI outlets. You can get things from the 12v side tripping the inverter's 120v GFCI doing whole house with shore cord into the inverter.
In the 5er when I had the battery disconnect switch on the neg path near the battery, I still had 12v to the RV. There was a neg path via the inverter internals and its chassis ground that by-passed the battery switch. The shore cord was plugged into the inverter and that is how the 12v got back to the frame and so to the 12v neg so the lights and fans still worked. (Should have stuck with using a disconnect on the pos path in that case)
So multiple "grounds" are how RVs work (or don't work if something is wrong)
