Originally Posted by kenenn
I was instructed that it is ' Ground Wire Off First " I could be corrected but that has always been my understanding.
You are correct, as long as its a negative ground system (the vast majority of things), that's the way it is. Now some vehicles can have a positive ground system, which then makes it all opposite but this is going to be the exception, not the rule.
An RV/travel trailer isn't most likely going to have as much metal near the battery as a vehicle, but it's just a best practice to do it this way to be sure. My propane tanks (which rest on the frame) are in very close proximity to my battery, which I usually remove the propane tank cover to gain more access to the battery box behind it.
Battery and Negative Terminal - How to Disconnect a Battery
How To Remove And Install A Car Or Truck Battery, Cleaning Corroded Terminals
How to Remove and Install a Car Battery - For Dummies
This has kind of been a hijack, but I'm thinking the OP was satisfied and had his question answered judging by his response in post #6.