Camper Trailers Tech Tips

12volt lighting switch box




12volt lighting
switch box

12volt switch box 

If you have several 12volt camp lights, each with their own switch around the camper trailer, it is very handy to have a central location to operate them from to avoid fumbling in the dark. While cigarette sockets & plugs are fine for what we use them for around camp, they do have a tendency to break contact through road vibration while driving. Hella/Merit style plugs & sockets or Anderson connectors are best suited in this situation as they provide a more positive fit.

bits & pieces

It seems whenever I do a 12volt project I need to run around to at least a half dozen shops, however in this case Jaycar had everything I required so it was just a one stop shop.

As the switch box is only going to be used to operate our LED lighting with a very low power draw, a cigarette plug with an inbuilt 3amp fuse was all that was needed. 

You could set the box up as a 12volt power point to run your laptop 12volt power supply, 12volt battery charger for a phone or camera if needed. In that case you may need a heavier cable depending on what accessories you want to run & also take the distance from the main outlet into account. Narva make a suitable 15amp fused cigarette plug with wires connected via screw clamps - part number 82110BL.

The Solar Wind online calculator is an easy way to work out what size cable to use by placing the amp draw of the accessory & cable length Solar Wind has given permission to reproduce the cable size calculator found on their website.

There are plenty of on/off switches to choose from. I liked the LED illuminated rocker switches rated at 30amps mainly because the buttons do not poke out to be broken off rattling around in the camper when travelling & they have a screw fitting to keep them in place, rather than just push fit. 

The 15amp wire twin core auto cable was more than enough for the job. I mainly went for this as the two cables are sheathed. A wiring diagram can be found below.

The red insulated crimp terminals are suited to the 15amp auto wire, but need a blue insulated crimp terminal for two wires. Alternately you could use a red piggy back insulated crimp terminal that has a male as well as a female terminal on the one fitting.

I used a red insulated crimp eye terminal for connection to the cigarette socket positive by simply unscrewing the nut. Make sure the insulation washer is properly seated before retightening as it can earth on the socket body blowing a fuse. The cigarette socket has a negative male tab for the earth wire connection with an insulated female spade terminal. 

Luckily there were two screws on the stone guard in the right position so I made slots in the back of the jiffy box to mount it from in camp.

parts wiring diagram
30amp switch switch wiring narva 15amp plug



one wire & two wires positive connection mounting slots

parts list

part number number description cost
HB6012 1 jiffy box - 197 x 113 x 63mm $6.95
WH3079 2 metres -15amp wire twin core auto cable $2.60
PS2002 3 fused cigarette socket $6.95
 PP2001 1 cigarette plug $6.95
SK0955 3 15amp rocker switch $4.95
PT4607 7 insulated female spade terminals - blue - of pack 8 $2.75
PT4507 3 insulated female spade terminals - red - of pack 8 $2.75
PT4614 3 insulated eye terminals - red - pack of 8 $2.75




Article by Rob



april 2013