Making Sense of Electric Cooking Equipment Specifications
When you're shopping for new electric restaurant equipment, it's easy to get confused by the different electrical specifications you'll encounter. Should you order 120-, 208-, or 240-volt equipment? Is your facility serviced by single- or three-phase electricity? What do those numbers mean, and do they impact the performance of the equipment? This guide aims to help answer those questions so you can make more informed buying decisions when you choose electric equipment for your facility.
First, let's strengthen our electricity vocabulary by understanding the difference between volts, amps, and watts. To illustrate how these concepts are related, imagine a current of electricity as a stream of water in a garden hose. The pressure with which that water flows can be compared to voltage. The rate at which the water flows can be compared to electrical current, or amperage, which is measured in amps. Voltage and amperage can be multiplied to give you wattage, which is an expression of how much work a piece of equipment can perform. Wattage is often the most important factor to consider in terms of the performance of electric equipment.
Cooking Equipment Wattage
For context, a typical commercial electric range burner uses around 3000 watts on its highest setting. That wattage could be supplied by equipment connected to 240-volt supply and drawing 12.5 amps, since 240 V x 12.5 A = 3000 W. Similarly, a hot plate powered by 120 volts and drawing a current of 12.5 amps will produce up to 1500 watts of power. The higher a component's wattage, the more work it can perform. In terms of cooking and heating equipment, that means the equipment can produce more heat in a shorter period of time.
It's important to note that in the example above, both types of equipment draw the same number of amps. If the 1500-watt element we described were designed to operate on a 240-volt power supply, it would only draw 6.25 amps of current to do the same work since 240 V x 6.25 A = 1500 W. The fact that higher voltages can produce a higher wattage at a lower amperage can play an important role in how the equipment is installed.
Keep in mind that a piece of electric restaurant equipment's overall wattage and amp ratings describe the equipment when all electrical components are powered on at the highest setting. That means an electric range with several heating elements will rarely operate at the full wattage listed on its nameplate.
Understanding Equipment Amperage
Electrical circuits and the circuit breakers designed to protect them are rated by how much current they can safely handle. Operators and contractors must take into account the existing amp load on a circuit to determine whether new equipment can safely be installed on it. This is where the amperage rating of equipment can make a difference. For the following example, keep in mind that for some applications, electrical codes require that an amperage load not exceed 80 percent of a circuit's rating.
For example, if a 30-amp circuit can be safely loaded with 24 amps' worth of equipment, and the circuit is currently connected to a series of equipment drawing a combined 20 amps, then a piece of 120-volt equipment drawing 6 amps could not be installed since that would take it over the safe limit of 24 amps. However, that same piece of equipment designed for 240 volts and drawing only 3 amps could certainly be installed on that circuit.
Ampacity also comes into play if you need to install another circuit to power new equipment. Circuits with higher amp ratings require thicker cables, which are more expensive than cables designed to carry lower amperage loads. That means that higher-voltage equipment may be cheaper to install if it must be installed on a dedicated circuit.
Always be sure that your electrical circuits can handle any new equipment you connect to them. The danger in overloading a circuit is that the individual wires can overheat and start a fire. That's why building codes are so strict about proper electrical installation.
Kitchen Equipment Voltage Supplies
By now you understand how watts and amps are related, and how the two can have practical implications when it comes to choosing kitchen equipment. The final piece in the electric puzzle is understanding how voltage plays a part in which piece of equipment you should buy. The biggest implication is that a piece of equipment's voltage requirement, along with its rated amp draw, will determine which type of plug it will come with and, in turn, which type of receptacle it can be plugged in to.
Plug and receptacle configurations are standardized according to National Electrical Manufacturers Association (NEMA) guidelines. Below are a few common NEMA configurations. The first number of each plug's name corresponds to the equipment's voltage requirement: 5 for 120 V and 6 for 208/240 V. The number after the hyphen corresponds to the amp rating of the circuit the equipment should be connected to.
All the different types of plugs and corresponding receptacles exist to ensure that equipment can only be installed on power supplies that can safely handle it. Connecting equipment to the wrong power supply could cause it to become damaged or prevent it from working as the manufacturer intends. Not every piece of electric equipment will include a plug and cord. Some need to be hardwired into a circuit by a professional electrician.
Why Do Different Voltages Exist?
Like your home, restaurant kitchens have 120-volt receptacles to power lighter-duty equipment like warmers, lights, and smaller countertop equipment. 120-volt equipment is limited in the power that it can produce because 120-volt circuits are rarely equipped to handle more than 50 amps of electricity. That limitation means that 120-volt equipment can rarely produce more than a few hundred watts of power, significantly less than the power needed to run heavy-duty equipment like electric steamers, ranges, and ovens.
Heavy-duty electric kitchen equipment runs on 208- or 240-volt electrical supplies. These powerful voltages can produce more wattage per amp versus 120-volt equipment, and circuits carrying them are typically equipped to handle greater ampacity, so they can be connected to much more powerful equipment. Whether your building is serviced by 208- or 240-volt power depends on how the electricity is obtained from higher-voltage transmission lines and distributed at your main circuit breaker. You'll likely have access to one or the other, but you should always consult with a certified professional before deciding which equipment to buy.
Single-phase and Three-phase Electricity
In addition to different voltages, you'll likely encounter the terms "single phase" and "three phase" to describe the power supply that a piece of electric cooking equipment can be connected to. As with 208 versus 240 voltage, whether a power supply provides single- or three-phase electricity depends on how your building is wired.
Three-phase is common in industrial facilities that need to power heavy equipment, but some restaurants also have access to it. Check with your contractor or landlord to see whether you have three-phase power in your building and to discuss whether installing three-phase equipment would be a practical choice. The important thing to understand about single- versus three-phase electricity is that three-phase equipment does draw fewer amps per volt than single-phase equipment, so many of the same considerations of choosing between 120 and 208 or 240 power supplies are true of choosing between single- and three-phase power.