ON-OFF. How hard can 12V switch wiring be... right? Well, I remember being completely baffled when I wired my first campervan switch panel. Unfortunately campervan switch panel wiring can be a little tricky to understand at first! So in this guide I will seek to enlighten you in the ways of the 12v rocker switch! We will look at simple 2 pin switches, all the way up to 5 pin gang rocker switch panels with USB chargers, and battery monitors. We will examine some 12v switch panel wiring diagrams, as well as how to wire a rocker switch to a fuse box.
I'm Shane, I've been teaching people to convert campervans for years; I'm the author of Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan, writer of The Van Conversion Newsletter, instructor of The Van Conversion Course over at Udemy. And full-time vanlifer for 4 years!
Now let's jump in and have a look at some 12V switch wiring and campervan switch panel wiring!
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Note: Before we hop in, you will definitely want to grab yourself a wiring diagram which you can get for free by signing up to The Van Conversion Newsletter.
Supplies list 🛒
What is a Switch?
A switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit. On command it can break a circuit, thus turning an appliance off. In campervans, we commonly use switches to control the lights in our van - among other appliances.
The most common types of switches in campervans are:
Rocker switch (left)
Isolator switch (middle)
Inline circuit breakers - can also be used as switches (Right)
Isolator switches are large and bulky; they are normally reserved for the leisure batteries and the inverter.
Inline circuit breakers are used to protect electrical components like your solar charge controller.
In this chapter we will focus on rocker switches, as these are what we commonly use to control our 12V DC appliances. They can be installed individually or in a group (switch panel).
12v Rocker Switch Positions: Poles and Throws
There are four types of rocker switch:
Single Pole, Single Throw (SPST)
Single Pole, Double Throw (SPDT)
Double Pole, Single Throw (DPST)
Double Pole, Double Throw DPDT)
Let's examine the terminology:
Pole: Poles refer to the number of separate circuits the switch controls. If a rocker controls just one circuit, it is a single-pole rocker switch. If it controls two separate circuits, it is a double pole switch.
Throw: Throws refer to the number of ON positions the switch can move between. A simple on-off switch, is known as a single throw switch. If it has two ON positions - eg. OFF, low, and high - it is a double-throw switch.
Let’s look at some examples …
Single Pole Single Throw - SPST
A rocker switch that just controls a simple LED light (ON-OFF) is SPST.
Single Pole Double Throw - SPDT
A rocker switch that controls an LED light with a high and low brightness (OFF-LOW-HIGH) is SPDT.
Double Pole Single Throw - DPST
A rocker switch that controls two simple LED lights (one turns ON when the other is OFF and vice versa) is DPST.
Double Pole Double Throw - DPDT
A rocker switch that controls two LED lights (one turns ON when the other is OFF) with a high and low brightness (OFF-LOW-HIGH) is DPDT.
12V Rocker switch terminals/pins
A 12V rocker switch can have between two and eight metal terminals/pins on the underside into which we wire.
Note: When a rocker switch has a built-in LED lamp (to indicate whether it is on or not), we generally add one extra pin (ground/negative) for the light itself. Rocker switches with lamps are very common in campervans.
12V switch wiring: How to wire a 2 pin 12V rocker switch
The 2 pin rocker switch (SPST) is the simplest rocker switch to wire up. As you might remember from physics class in school, this switch is simply wired between the battery source and the appliance - it turns it on and off.
In a van conversion, we must fuse our appliances to protect them; so we install a 12V fuse box to help with that. We install the switch between the fuse and the appliance.
How to attach a wire to a rocker switch
The pins on the underside of the rocker switch are male blade terminals. We can connect a wire to these pins using a female 'quick disconnect' crimp connector. Learn about crimp connecting in this guide.
How to wire a 12V switch with LED (3-pin)
3 pin rocker switches are very common in campervans. They have 3 pins because they have a small LED lamp which needs ground/negative. Here is a diagram of how to wire a 12V switch with LED:
One of the three pins on the rocker switch should have a brassy colour - this is the negative of the LED lamp. We can wire this pin to the negative bus bar of the fuse box.
Of course, we must make sure our fuse box is grounded to handle this. The fuse box is grounded through the common negative bus bar.
12V switch wiring: How to wire a 3 pin switch panel
When we are installing many 12V rocker switches, we typically bunch them together in a switch panel. Switch panel wiring can be a little tricky, so let's dive in and have a look at how to deal with it.
One of the most common switch panels is the one shown in the photo below. It has the Positive IN and LED Negative OUT already wired up and ready for connection to the fuse box. All that is left to do is wire the appliance into the middle pin.
However, there is a problem with the out-of-the-box wiring of this panel... Notice that all the Positive INs are daisy chained together. Where does the fuse go? We have two options of dealing with this:
Option #1 :Inline fuse
Our first option is to insert an inline fuse on the wire running to the appliance (from the middle pin).
Option #2: Fuse box
Our second option is to rewire all the daisy-chained Positive INs to run to the 12V fuse box (ie. remove the daisy chains). Each switch will have an individual blade fuse in the fuse box. The negatives can stay daisy chained (negative is just common ground in DC systems.
12v switch panel wiring diagram
The above 12V switch panel wiring diagram shows you how to wire a simple rocker switch panel to a fuse box. Wiring the switch panel to the fuse box is a very neat way to keep all your fuses in one place (rather than a bunch of inline fuses).
12V switch wiring: How to wire a panel of 3 pin rocker switches with USB chargers
Another very popular type of rocker switch panel is the one shown in the following image; it has USB chargers, a cigarette lighter, and a battery monitor.
The wiring for this type of panel will be much the same as a standard 3 pin rocker switch panel. Notice how we run into the same problem as before with the out-of-the-box wiring of this panel... All the Positive INs are daisy-chained together. The USB socket, cigarette lighter, and battery monitor aren't even fused!
So we can choose to use the inline blade fuse method discussed previously (the blade fuse holders are already wired up).
Or we can choose to wire everything back to our 12V fuse box, in which case we will need to rewire all the daisy-chained Positive INs to run to the fuse box (ie. remove the daisy chains). We will also need to also remove the wires with the inline fuses.
12V switch wiring: How to wire a 5 pin gang rocker switch panel
We're getting into more tricky territory now. Some people buy 5 pin switch panels and then nearly lose their minds trying to wire them. Each rocker switch has FIVE pins on the back. Each switch has a dim backlight that always remains ON, it also has a main LED lamp that turns on when the switch is turned ON.
Why the heck are there five pins?
Positive IN for LED backlights (always on)
Negative OUT for LED backlights (always on)
Positive IN for appliance
Positive OUT for appliance
Negative OUT for LED lamp (Turn ON when switched)
However, once again the lovely people who supply the switch panels have daisy-chained the positive appliance INs together for us. This is fine if we are going to use inline fuses on the way to our appliances. However, if we want to fuse everything from our 12V fuse box, once again we will need to remove the daisy-chains and wire each switch individually.
Note: If you are installing 12V cigarette lighter sockets in your van, make sure you label them with their max ratings.
Here is an excellent video from a guy who wires up (and even customizes) a 5 pin gang rocker switch panel. He shows excellently how to wire a rocker switch to a fuse box.
And there we have it! Everything you need to know (and probably more) about 12v campervan switch panel wiring! I found these switch panels confusing when I first came across them, so I hope you found this article useful!
Don't forget to subscribe to The Van Conversion Newsletter for everything you need to get started with your own van conversion (I'll send you a free wiring diagram when you join).
If you're looking for some guidance with your van conversion, you might be interested in Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan. In the 380-page book (or ebook), you'll learn directly from me how to convert a van into your dream home - no prior experience needed!
Until next time,