How to wire switch for 12v dc fridge

If you are unsure you should have professional wire it. Truck fires are very common and usually caused by improper wiring. That said, if you want to tackle it here is how you should do it.

12 gauge stranded automotive wire will be fine, although 10 ga. is better as it reduces voltage drop. Both the 12v+ and 12v- wires should be the same size.

The ground wire (green) on that fridge is for use in RVs that also are connected to shore power (120v) system to allow for drain/discharge of excess current. You do not need to worry about the ground (green) terminal in your application in your truck unless your inverter has 120v shore power pass thru where you can plug your truck into your house or another 120v power supply to keep the batteries and such charged.

Starting at your 12v+ (red) battery terminal install a 20 amp inline fuse holder, weather proof, and using either 10 or12 ga. wire run that wire to one terminal on the toggle switch you wish to use to turn the fridge power supply on/off. Coming out of the other terminal on the SPST toggle switch run the same size wire to the #1 terminal (orange/12v+) terminal on the back of your fridge. This will provide the 12v+ supply to the fridge and allow you to remotely interrupt it with the toggle switch. DO not go directly to factory dash mounted switches as they usually are not designed for full current draw and only switch relays somewhere else to tie into. The above instructions assume you are installing a dedicated 12v/20A rated toggle switch!

Then from the fridge take another 10 or12 ga. wire (same size as you used for the 12v+) from terminal #2 (the black wire) down to chassis ground. The best place for this to to run back to the battery negative (-/black) terminal or one of the ground lug points provided by the chassis maker for adding accessories. This line does not need to be fused as it is the negative/ground return.

Make sure these wires are protected from rubbing, chaffing and are secure. Split loom tubing is great for protection. 12 ga. stranded automotive is the best choice as it has an oil resistant jacket whereas wire for buildings such as THHN does not. Do not use solid wire as the vibration will cause the connections to come loose and eventually build up heat, which will result in a fire.

 

Think I'd wire it up so the negative is on the switch. otherwise everything else the person above said.. or use a relay but that's more complicated, slightly

 

I don’t have a fridge in my truck since I’m local, BUT….. aren’t inverters made for this ?……. Just curious

 

Some say switching the negative side of a DC circuit is safer but really there is little difference. Perhaps a little less heat at the switch terminals, but not really significant.

If you did want to switch the negative (chassis ground) just run the 12v+ from the fuse output directly to your 12v+ in on the fridge, then run the - wire up to the switch, the the other terminal on the switch to a good chassis ground or the negative terminal on the battery.

8 ga. wire is a good bit of extra safety and will reduce voltage drop so you get the best possible performance.