On Tuesday evening, Linda flicked on a light switch in our living room. The switch controls some accent rope lights around the bottom of our kitchen peninsula, an LED light in a curio cabinet above our kitchen peninsula, and safety lights at our entry step and on the steps going up into our bedroom. We turn these 12-volt lights on at night as minimal lighting and then turn them off just before crawling into bed (there is a second light switch in the bedroom that controls the lights as well).
When Linda turned the living room switch on, the lights flickered and then went off. She then turned on the switch in the bedroom and the lights came on. She went to bed and I was still up watching basketball. Around 11:00 p.m. the lights went off and I could smell something burning.
Linda wasn't asleep yet, so she hopped up and we both started looking for the problem. We've been through enough RV fire training to know a fire in an RV can get out of hand very quickly.
I went outside and looked in the basement compartment - no flame and no smell there. When I came back in, Linda was on her hands and knees where she had discovered a charred connection to the accent rope lighting. She's our electrical expert, so she quickly popped off the wall switch nearest the rope lights and disconnected all the wires to the switch.
Other 12-volt lights in our bedroom were dim. Hmm.
We have a "power control center" conveniently located in our bathroom above the toilet.
The left side contains the breakers for our 120-volt electrical system and the right side is our fuse panel for the 12-volt electrical system.
Note: I don't want to get "into the weeds" on RV electrical systems here, but after you read all this, you may want to check out our page on RV Electrical Systems where we attempt to explain them in layman's terms from the minimum you need to know to the more complex.
On the inside of the cover for the fuse panel is a listing of what each fuse goes to.
Unfortunately, there is nothing referring to the rope lights and floor lights in question. But we do have a fuse for the bedroom. I replaced that fuse (we always carry spares) and the bedroom lights then worked properly, but the rope lights and step lights did not.
With the power disconnected from the switch, we determined we were safe for the evening and decided to tackle a fix tomorrow.
This morning, I took photos of the burnt rope light connection.
When we are away from the rig at night, we often leave those rope lights and step lights on so we can see when we return. Now, I don't know if this short in the rope light connection would have actually started a fire, but it sure looks like it could have. And that's a scary proposition.
Linda started delving into the electrical issue. Unfortunately, in her rush last evening, she didn't note which wires connected to which poles on the wall switch. She took the other switch (the one in the bedroom) out of the wall to look at how it's wired. That switch is part of a four-switch set-up like this.
We noticed that one wire on that switch was connected to the switch next to it - the one that controls the bedroom lights that dimmed last night. That must be why the original short also caused a problem with the 12-volt bedroom lights.
We ripped out the rope lights last night, and Linda cut the wires to the charred connection so we could cap them off. But she still wanted to be able to use the other lights on the circuit, so we tried to work through that.
The living room switch looks like a pretty typical RV 12-volt rocker switch.
However, we did a little research and found there are all kinds of different switches. Most switches are the ON-OFF variety where the item being powered is OFF when the bottom of the switch is pushed in, and the item is ON when the top is pushed in like in the photo above (assuming the switch is mounted vertically). There are two poles on the back.
But this particular switch is an ON-ON switch meaning the circuit is closed and the lights are ON in either position. There are three poles on the back of the switch and we learned that the 12-volt power goes to the middle pole.
This type of switch is used when the wiring is such that you can turn lights off and on from two places in the RV. It's the second switch in the bedroom that ultimately controls whether power to the lights we're working with is off or on.
So much for thinking "a switch is a switch". There are all kinds of configurations for RV switches. In addition to the ON-OFF and ON-ON, some are MOM switches, meaning "momentary". In MOM switches the item is only ON when the switch is pushed, but then it springs back to OFF when you stop pushing it. There are also illuminated switches which have an extra terminal so the switch lights up when in the ON position. And there are various combinations of all of the above.
It all became very confusing, but we ultimately put our heads together and figured it out. Now, the rope lights are out of the circuit (until we replace them) and the curio light and floor lights work with both switches. It was gratifying to know we can figure this stuff out - it may take awhile, but together we do pretty well.
We have no idea why the rope lights shorted out. Perhaps the mice we had last summer/fall chewed on the wires, or perhaps the connection just loosened with the normal movement of the RV going down the road. All we know, is we're glad it happened while we were home.
The majority of RV fires that occur while an RV is stationary start in the 12-volt electrical system, and I've seen statistics that indicate these electrical fires make up 25% - 35% of all RV fires. With the constant vibration throughout an RV as it goes down the road, many things such as screws, nails, staples, and electrical connections can wiggle loose.
So, how do you prevent something like this from happening? Well, we all should check our battery connections from time to time and it's a good idea to check all the connections to the breaker box and fuse panel at least once a year (or have an RV tech do it when you're in for service or repairs). But it's not practical to think that everyone is going to check every 12-volt connection in the RV. Heck, there will be some that are nearly impossible to get to. And even for the accessible ones, people just aren't going to pop off every switch and look at the wiring behind it, and we certainly won't do it after each move.
Hopefully, a short will blow a fuse and cut off electricity to the offending circuit removing the heat source, but in our case those rope lights certainly got hot enough to have ignited any combustible material that might have been in contact with them.
Of course, fires are rare in RVs, but that's little comfort if one of those rare occurrences happens to you.
Let's at least suggest this. When you get an RV and are testing out your systems, verify and document exactly which breakers and which fuses match up to every light, accessory, appliance, etc. If nothing else, at least you will learn a little bit about your electrical system. :)