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June 30, 2016 Staff

How-to Determine Electrical Power Needs of a Food Truck

You will almost certainly need electrical energy for your truck, unless you plan on vending from a hot dog cart. Even then, if you want to do anything cool you’ll want to upgrade so you have power. How much power exactly will you need for your truck? That is tricky and depends entirely on the Wattage of your equipment. Let’s do a quick introduction to the physics of electricity so you understand the terminology. When we start the build process, we work with customers to determine how much power they’ll need to operate they’re specific type of business.

Understanding Watts and Volts

electric sparkWatts (W for short) are a measure of electrical power. Electrical energy is measured in units of Volts (V for short) and electrical current is measured in Amps (A for short). Electrons carry electrical charge. So current, is a gauge of the flow of electrons. Voltage is basically a measure of the electrical energy between two points. So a AA battery has 1.5 V of energy between the two poles (the top and the bottom of the battery). Your standard household outlet has 120 V between the two poles (the plug holes, bonus points if you can quote the line from Seinfeld).

Electrical power (symbolized by P) is defined as:

P=VI

You’ll notice a major discrepancy in your electrical equipment. Your generator’s maximum output is measured in Watts, but your fridge may only list the required voltage and current (or amperage) for operation. Here’s another post from the folks a New Electric that explains this topic even further. 

How Much Power Will You Need?

You’ll need to figure out how much total power you’ll need on your truck/cart. And here is how you do it:

To calculate the required wattage of any appliance, multiply its required voltage by its required current. The current should always be listed somewhere on the equipment itself (near a serial number perhaps). If your equipment is plugged into a normal household outlet you can assume it uses 120V. Otherwise, it may list the required voltage on a label or in the manual. Plugs generally only have certain voltages: 120, 125, 240, or 250 V.

Just multiply the voltage and the amps together and you get Watts. For instance, a refrigerator may plug into a 120V outlet and need 10 Amps of current. Doing the math, you should get 1200 W of power needed to operate your fridge. So you now know that you need at least a 1200 W generator. To get the total max output needed, just add up all the wattages of all the equipment on board.

Homework: Let’s say your hot water heater needs 15 amps and plugs into a normal outlet. You also have a 3000 W fridge, and an air conditioner that needs 250 V and 10 Amps. What is the total wattage of the equipment on board your truck?

When considering how much power you’ll need, you will also need to take any other removable equipment into consideration. In this case, I am talking about stuff like mixers, electric tabletop deep fryers, portable griddles, etc.

When planning your power needs definitely overshoot. A lot of food trucks could operate at 6500 W to power our onboard equipment. Still understanding that heating equipment (like tabletop fryers) eat a lot of power and that you may want to expand your menu offerings later, investing in a 10,000 W generator early on can safe a lot of money and hassle in the long run.
Pro Tip: No matter what your wattage requirement, the most current you’ll be able to draw is 50 Amps. Make sure that your main power line is rated for 50 A. You do not want it to be rated for less because the heat produced if you accidentally draw more than your power cable is capable will melt your cord and your connections.

Now you may be asking what is the cost of buying a generator? You have some options.

Solar panel generators are an option, although they do become cost prohibitive for many. Generally these systems are on the order of $1500 per kW-h (generally electrical usage is measured by watts used in an hour, here kW means 1000 W).

You can also opt to purchase quiet generators which are roughly triple the price of a standard generator. They are basically packed with tons of insulation, and the parts are rated for a higher heat tolerance, since that sound insulation also makes the engine get hotter.

Finally there are your standard outdoor portable generators. They are fairly inexpensive (depending on brand) and definitely do the job. One example of a work horse is the Generac 10kW generator. These often come with a one year warranty to replace any broken parts.

Where you buy your generator/power supply depends on the type of power supply needed. Most portable generators can be purchased at Home Depot, Lowes, Amazon or any hardware store. Amazon.com is another option to save a lot of money on cost of shipping and taxes. The heavier duty generators and the quiet ones will most likely need to be bought from specialized dealers in your local area. You can also check out RV dealerships and supply stores to see what options are available to you.

In fact, I highly recommend looking in the RV section of any store, or an RV supply store. Many of the products developed for RVs are perfect for food trucks because those items are built to maximize space and utility. Exactly what you’ll need to be efficient in your food truck operation.

lightOutlet Adapters

The final thing I’d like to mention regarding power is this: make sure you have different outlet adapters. I have encountered all different types of outlets. If you know there is going to be power available at any location, make sure you visit the location ahead of time and look at what is available.

I’ve had to make adapters that fit 2, 3, and 4 prong plugs that draw 15, 20, 30, and 50 A. There are so many variations, it gets downright frustrating. But there are a few standard outlets that you can count on:

  • Most generators will have a 4-prong, 50 A receptacle. It is a 14-50R type outlet, so you will need the male end (the side with the prongs) to plug in. You will also find these outlets on walls for industrial purposes. Forward thinking breweries and events will have these outlets as well.
  • Another common generator connector are the twist locking 20 and 30 A outlets. They come in 2 varieties: 3 and 4 prong. The technical standards are NEMA L14-30 and L14-20 (the 30 and 20 refer to the amperage capacity of the connector) for the 4-prong plugs which I’ve needed far more than the 3-prongs.

Most of these outlet types you can find at Home Depot. Make sure you identify if you need a male or female component, and the component type (which is always written right on the plug/receptacle face).

Always consult an electrician or professional like M&R Specialty Trailers and Trucks about your power needs. Powering a food truck is no joke, and mistakes can be costly. You could start a fire or cause serious physical harm to yourself.

Please be careful!

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