Micro Minnie - Tongue wiring issue

[backtrack15]

I was poking around under my Micro Minnie and looking at the wiring to see where the factory tied-in the pre-installed wiring for the solar controller. As part of that, I noticed what seems to be an excessive amount of wiring that is unprotected (from the trailer batteries) should a short occur. The relevant portions of the factory wiring look something like this:



Would it not be better to have more of this wiring on the protected side of the 30 amp breaker as shown below?



I elected to keep the breakaway switch on the unprotected side in that schematic. For those that are interested, the +12V line from the solar controller is unfused (from the factory) and also connects on the unprotected side of the breaker (not shown).

[DavidM]

Fault protection (fuses and breakers) is a total mess on RVs, particularly trailers. Some have no protection from the battery.

In your case if the wire you want to protect is 10 gauge or greater, then hook it up to the load side of that breaker. If it is less than 10 gauge, it needs an inline fuse.

David

[backtrack15]

It's interesting to look around for sure. Each project has a way of provoking secondary projects as discoveries are made. I'm guessing I'll end up reworking the wiring to get as much as possible on the load side of that breaker.

[Morich]

On the other hand have you improved the safety or only adding more trouble if some wire does get damaged?

Doesn't the jack wiring already have protection from the inline fuse? Same with the +12 from the truck which likely has a fuse in the truck!
By adding load to the 30 amp, are you not also making it more likely to trip and you may then need to find two problems instead of one and the 30 amp breaker is most likely to high for the wire size used.

I see the main thing may be that if you trip the 30 amp as well as the inline, you may not be able to lift it to disconnect to go for parts! Also when the 30 amp is tripped, what powers the breakaway? Think of what happens if the 30 amp trips while driving and the brakes suddenly go on. Not a happy thought if you are in traffic.

[Old Navy]

The jack should have it's own inline fuse. On my Minnie there is an inline 30A ATC fuse. On most of the trailers I've looked at, the jack was wired directly to the battery.

For the 12V from the truck, the fuse is on the truck near the battery, to protect the truck wiring.

The breakaway switch is fed by the RV battery, not the truck 12v, as during a breakaway event, the trailer wiring to the truck will be destroyed, possibly causing shorts while doing so.

[backtrack15]

Originally Posted by Morich

On the other hand have you improved the safety or only adding more trouble if some wire does get damaged?

Doesn't the jack wiring already have protection from the inline fuse? Same with the +12 from the truck which likely has a fuse in the truck!
By adding load to the 30 amp, are you not also making it more likely to trip and you may then need to find two problems instead of one and the 30 amp breaker is most likely to high for the wire size used.

I see the main thing may be that if you trip the 30 amp as well as the inline, you may not be able to lift it to disconnect to go for parts! Also when the 30 amp is tripped, what powers the breakaway? Think of what happens if the 30 amp trips while driving and the brakes suddenly go on. Not a happy thought if you are in traffic.

My motto is always "first, do no harm." That's part of the reason I posted this question. I'm not an expert at all, I just thought it was a bit odd when looking at it.

I believe the system has two potential sources of unregulated current, the truck batteries/alternators and the trailer batteries. The truck has a fuse under the hood. That fuse provides protection of the wiring from the "truck-side." The remaining 13-feet of truck wiring may not have any protection from the trailer batteries if it somehow shorted within the truck (connection came loose, wire insulation frayed due to rubbing). There's also the section of wiring on the trailer from the tongue to the junction box and back to the breaker. That's why I proposed moving that connection to the load-side of the trailer's 30-amp breaker. The truck shouldn't add load to the breaker, other than the modest charging current back to the trailer batteries due to charging.

The proposed wiring for the breakaway switch is basically unchanged. It gets power directly from the trailer battery regardless of the breaker's status.

The tongue jack has an in-line fuse. Moving it to the load-side technically isn't required. By doing so I only gain protection for the 18-inches of wiring "upstream" of the in-line fuse.

The solar controller wire is interesting as it currently goes from the battery side of the breaker directly into the front wall of the trailer and across the width of the trailer before appearing in the storage compartment. My first thought was that it would have been safer for them to connect it on the load-side of the 30-amp breaker (10 awg wire). Maybe they were thinking solar charging might trip the breaker in reverse? Or maybe they thought of the solar as a "source" that the rest of the trailer needed protection from? Since it has a source on both ends and may well rub on anything inside the wall as the trailer bounces down the road, I may end up putting a fuse on both ends. I'm just thinking out loud.

Edit - Probably a fuse on the "battery" end of the 10-awg solar wire is the only real need. I forget sometimes that the short-circuit current of the solar system is modest and no problem for a 30-amp wire. Also, if anyone is interested, I believe the link below is a good representation of the wiring at the front of my trailer. https://www.winnieowners.com/forums/...icture2004.jpg