Power delivery is inconsistent as the alternating current goes to zero once each cycle.On the other hand, using single-phase power does have its disadvantages. 120-volt 60 cycle AC electricity is the standard in the United States and almost every appliance, light bulb, or tool that you buy is designed to use this standard. The cycle of the delivery occurs about 60 times per secondīecause it only takes two wires to deliver 120-volt single-phase power, it is more economical in a residential setting.Delivery of single-phase 120-volt service is accomplished using one hot wire and one neutral wire.A complete AC single-phase cycle occurs every 360 degrees.The AC voltage peaks occur at 90 degrees and 270 degrees.Single-phase power has some distinct characteristics. You will recognize the large pot transformers that hang on the utility poles or the squat secure boxes located near your home. A transformer is then used to convert the three-phase power into single-phase power suitable for delivery to the home. In most municipal electrical systems, power is delivered to the area where it is to be used via a three-phase distribution network. Systems that transmit large voltages across long distances can use smaller wire than a two-wire single-phase system. The transmission of three-phase power is more efficient because the load is spread over three wires. The most predominant use is the long-distance transmission of very large voltages. Three-phase electrical service is also used in the United States in several ways. This is the defacto standard in the United States You may recognize these as the black and white wires that you find in the electrical box if you replace a light fixture or repair a wall switch. Single-phase power is delivered through one wire and a neutral wire. Your home electrical service in the United States is almost surely 120-volts alternating current single-phase power. Read on to learn what you need to know to do the job safely. Don’t risk damaging your home, shop, or yourself. Trying to make a single-phase tool or appliance work in a three-phase system can be a shocking experience, literally! Before you begin adding wires, motors, or heavy appliances to your electrical system, you need to understand the fundamental differences in single-phase and three-phase. 3 phase delivers a more consistent power supply.Phase refers to the method of delivery of the power load. What is the difference between 208-volt and 240-volt? 240-volt is single-phase power, while 208-volt is 3-phase power. When many of us see a specification for 208 volts, it gets confusing. Some household equipment may call for 240 volts. We are all familiar with standard home electrical labeled as 120 volts. It may be confusing to many people as they look at electrical equipment to see the specifications call for 208-volt service instead of the expected 240 volts. Please read my disclaimer for additional details. As an Amazon Associate, I earn from qualifying purchases. *This post may have affiliate links, which means I may receive commissions if you choose to purchase through links I provide (at no extra cost to you).