I am going to have to disagree here.
I have an older copy of the NEC, so forgive me if my information is not up to date.
In the RV section (551-11) of my older copy of the NEC, which by the way only consists of a few pages, there is only a mention that RVs shall have a distribution panel board with circuit breaker or fuse protection with an insulated (not grounded) neutral. It does not state anything about a prohibition of a switched neutral.
The only place in the NEC where I found a prohibition on circuit breakers was in the general requirements; Section 380-2, where it states that switches or breakers shall not disconnect the GROUNDED conductor. Note that the requirement is for the GROUNDED, and does not mention NEUTRAL conductors.
Remember, in a RV, the ground connection is made at the shorepower pedestal, so potentially either the BLACK or WHITE wire in the RV could become the hot side (depending on whether or not the pedestal is mis-wired). So which side is truly neutral? Neutral can be either wire, depending on the correct or miswired shorepower wiring.
There is also an exception in the NEC (Exception1) in section 380-2 that states a circuit breaker on the GROUNDED connection is permissible if all conductors are disconnected with a switch or circuit breaker simultaneously. So then, Exception 1 explicitly permits a circuit breaker on the neutral side.
Exception 1 is commonly done in boats as the hot and neutral connectors are connected together with a bail, so that if one side of the breaker is flipped, then both sides get flipped.
Like this:
(the top two breakers are the hot and neutral side of the main breaker)
In fact, there are actually 2 pole breakers available explicitly for this purpose (breakering both hot and neutral simultaneously). I had one in my last boat.
So in my view, it is certainly indeed permissible in a RV according to the NEC to have both hot and neutral breakers as long as they are tied together so they simultaneously trip.
Since I am retired, I don't have the funds to buy a current copy of the NEC, so my references are for the older version, which admittedly is outdated. I would be interested to see where newer versions of the NEC might differ.
In the boating world (which for purposes of this discussion is a parallel to the RV world as the same unsafe conditions can occur):
USCG Regulation (which is actually federal law) 33CFR183.455 requires that all ungrounded circuits be overcurrent protected. It is also backed up by the ABYC (American Boat and Yacht Council E11.7.2.2.1.1), which is the marine industry's version of the RVIA.
Again, the reference is to UNGROUNDED and not Hot/neutral.
So then, we have one industry that is complying with industry and gov't standards (boats) that uses a dual breaker, and another industry (RV) that uses a single breaker for the same safety condition.
So why the difference?
I can only conclude that the RV industry is interpreting the NEC differently than the marine industry. Perhaps the RV industry is meeting minimum standards, but not sufficiently to ensure safety in my view, and certainly not best practices.
So, are boats built better/safer than RV's? I know my answer to that. In my RV at least, there are plenty of examples of shoddy wiring - both in design and execution - that are far from "best practices".
In conclusion, ask yourself the following:
1. are their shorepower pedestals in campgrounds that are mis-wired (hot and neutral reversed)?
2. is it an unsafe condition to operate a RV in this situation whereby the potential exists that you have an ungrounded current carrying conductor that is not protected with a breaker?
3. does the NEC permit wiring techniques (by breakering hot and neutral) to prevent such a safety issue (see NEC 380-2 Exception 1)?
This is still a huge safety issue in my view. At minimum, I encourage all of my RV brethren to invest in a device to check the state of the shorepower connector prior to connecting your RV to it.
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