Updated on September 29th, 2020
A van 120-volt electrical system is not a necessity. It’s a luxury. We like luxury. Luxuries such as using a normal dorm fridge instead of a 12-volt model. Not to mention, Andy wanted to use power tools powered by the sun. *Facepalm*
A quick safety note: if you have never done any electrical work before please proceed with caution. 120 volts of electricity is enough to kill you. Always assume a wire is live unless you have tested it with a voltmeter. If you are unsure of anything either contact us or a qualified electrician
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Inverters for Van 120 Volt Systems
Modified Sine Wave vs Pure Sine Wave
Inverters take 12-volt power and convert it to AC current, or 120 volts. Two types of inverters are available, modified sine wave, and pure sine wave.
To understand how an inverter works you must first understand how AC power works. With direct current (DC) the electrons only flow in one direction. You have a positive and a negative. Alternating current (AC) the polarity switches 60 times per second. If you looked at a graph of the voltage you would see a sinusoidal curve, in both the positive and the negative as the current switches directions. The reason we use in houses AC is that it is much more efficient to transmit over long distances.
Modified sine wave inverters do not perfectly match the AC curve that your electronics are expecting. It is closer to a staircase going up and a staircase going down not a smooth curve. A pure sine wave inverter mimics that AC sinusoidal curve very accurately. That doesn’t mean there is anything wrong with the with modified sine wave inverter. They are less expensive and less complicated. Things like laptops, phone chargers, or anything that charges with a “power brick” don’t really care about it at all. Some things do care about the difference. Electric motors, desktop computers, televisions, and refrigerators may not run at all or would run poorly with a modified sine wave inverter.
Choosing an Inverter
We decided to use a normal 120-volt dorm fridge in our van, because of this we needed to have a pure sine wave inverter.
Inverters are also rated as either continuous or surge. Surge current, may say 2000w surge, which may mean that it is only 1000w continuous. You will want to keep that in mind when planning which inverter to purchase. Surge current is designed to allow you to start things like fridges or electric motors that have a high startup current but lower running current.
You should mount Large inverters as close to the batteries as possible to limit wiring length and voltage drop. Because of the heat they product during operation you should also mount them in an area with airflow. We mounted our inverter under the bed. We left the bottom of its compartment open to allow for airflow.
Wiring
Vans are not like houses. They move, flex, and bounce down the road. For that reason, you should only use stranded wire in your van 120-volt system. Solid core wire is not designed for the vibration seen in a van because of this can be subject to work hardening and cracking. A good source of smaller gauge stranded wire is heavy-duty extension cords. They are inexpensive and have a built-in protective jacket.
Our 1000w inverter has a maximum sustained current of 8.3 amps. We chose to use 16 gauge wire which is rated to carry 10 amps.
Van 120-Volt Circuit Protection
Van 120-volt wiring requires protection on each circuit to protect the wiring from overcurrent and prevent fires. You do not want to rely solely on the inverters internal overcurrent protection. Typically circuit protection used in van builds is either fuses or household type circuit breakers. If you choose to use household circuit breakers, make sure they are designed to use with stranded wire.
Since we only have one circuit connected to the inverter and no provisions for shore power, we used a 10 amp inline glass fuse on our system. It didn’t make much sense to mount a big breaker box for only one circuit. It is located as close as possible to the inverter between the inverter and the rest of the 120-volt system.
Van 120-Volt Outlets
The last part of your van 120-volt system is the outlets. Vans can be wet places sometimes and for that reason, it is a good idea to install a ground fault interrupter (GFI). While the job of the fuse is to protect the wiring, the job of a GFI is to protect you. A GFI is a clever little device that monitors the Hot and Neutral sides of the circuit and makes sure the current is balanced on both. When everything is normal current flows between hot and Neutral. If something were to happen, such as dropping a hairdryer into the water a small amount of current would return along the ground instead of the hot or neutral. The GFI would detect the imbalance and cut off the circuit.
Two types of GFI are available, one that is integrated into an outlet and a breaker type that installs into the breaker box. You have probably seen the outlet type in your bathroom or kitchen, it has “test” and “reset” buttons on it. When installed as the first outlet in the string it also protects all the subsequent outlets in the string. The other style simply replaces a standard circuit breaker in your breaker box and protects the entire circuit. This type of out is what you will want to use if you have anything that may be hardwired without plugging into an outlet, but that would be a pretty unusual circumstance.
Since we do not have a fuse box or any hardwired appliances we went with the outlet type GFI. We mounted out at the rear of the van and protects the outlet by the fridge and the one up front behind the driver’s seat.
Electricity can be dangerous. If you are unsure or have any questions do not hesitate to contact us by leaving a comment below or send an email to info@abroadreachtravel.com
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