Electrical Issues – 12 Volt

Note to readers…

This section is House 12 Volt, not Chassis 12 Volt, you can find some info on those types of electrical issues here: Chassis Repairs & Fixes

The House 12 Volt system is for the most part separate from the chassis. Most Class A rigs have 2 or more 6 Volt deep cycle batteries, and 1 or more 12 Volt starting batteries. The interconnections are few, the manufacturers like to treat them as separate systems but there are devices that both sets of batteries power…such as the propane leak detector and the CO detector. 

In general, the House 12 V system powers the interior lights, water pump, spark devices to light various propane systems, antenna amplifiers, sometimes the retractable step (this is often wired to the chassis battery), and many other devices that come as options in a big RV. This section of the blog will cover only issues with the house 12 Volt system.


Transfer switch info – No repair required

Here’s where my automatic transfer switch is, in that box on the back of the 120 Volt Circuit Breaker and 12 Volt fuse box. See the large red wires above a bundle of smaller variously colored wires? Take off that side panel and the ATS is there. I have not opened it yet, but since it is working, I’ll leave it alone.

For those unfamiliar with large RV’s, most have this transfer switch that protects the equipment on board if you’re both plugged into shore power and start the Generator (Genset). The switch only connects to one source at a time, either shore power OR genset, not both. Fire would be a likely result if they were connected together. It’s really just a large relay.

Edit – Sept. 2011

I had an electrical issue that required pulling the box shown above so while I had it out anyway, I opened the Transfer Switch section and checked it all out. Tightened the screws on the relay. Wiring and connections all looked good.


Closet Light fixture…Dec. 2011

The light fixture in the double closet in my bedroom started to crumble with age and melt from the heat of the 8 watt 12V bulb. I pulled it apart earlier in the year and did my best magic on it to get me a few more months of life but it was capute now. The actuator shaft wouldn’t stay in position so I’d have trouble closing the closet door. Plus the electrical switch wouldn’t turn on the light every time. So it was time to find a replacement if I could.

After a couple hours online, I discovered that my fixture wasn’t available anywhere. There were some similar at Camping World but I really don’t like buying from them plus they wanted over $30 for something that ‘might’ work. Other sources had LED type and at this time all LED stuff was really expensive. OK, I’ll make my own.

Checked my parts bins and came up with a 12V bulb socket, and a lever actuated microswitch. A few wiring connections, a screw or two, and I had a new door actuated closet light. I tried to figure a way to save the old assembly but it was just too far gone. Tossed it in the trash.


It’s out of the way so there’s never been the occasion of bumping into it or anything. The light fills both sides of the closet, and the lever is easily actuated by the metal hinge there to the left of my finger so it will last a long time. It’s not as pretty as the original plastic housed setup, but it works fine.