How does Electrical Power work?

If you’re not electrically minded, think of electrical power as something easier to visualize like mechanical power. Mechanical and electrical power are very different, but both deliver power using pressure and flow, and the power delivered can be calculated by multiplying the pressure times the flow. In mechanical power, many terms are used to describe the pressure (Pounds per Square Inch, etc.) and flow (Gallons per Minute, etc.). In electric power, one term is used to describe the pressure (Voltage) and two terms are used to describe the flow (Amperes, Current).

In the earliest days, electrical power was delivered using Direct Current (DC), meaning the power flows in one direction like a water hose. Now, electrical power is delivered using Alternating Current (AC), meaning the power flow is constantly alternating directions. This change took place because electrical power can be delivered more efficiently using Alternating Current (AC) than Direct Current (DC). In the US, 60 Hertz (cycles per second) is the Alternating Current (AC) frequency. In some countries, 50 Hertz (cycles per second) is the Alternating Current (AC) frequency.

What does 1 (Single) Phase Power mean?

If you’re not electrically minded, think of 1 (Single) phase power like a one pedal bicycle where one (pushing leg) provides power.

Single Phase power refers to a two wire Alternating Current (AC) power circuit. Typically there is one power wire and one neutral wire. In the US, 120V is the standard single phase voltage with one 120V power wire and one neutral wire. In some countries, 230V is the standard single phase voltage with one 230V power wire and one neutral wire. Power flows between the power wire (through the load) and the neutral wire.

What does 2 (Dual / Split) Phase Power mean?

If you’re not electrically minded, think of 2 (Dual / Split) phase power like a two pedal bicycle where one (pushing leg) or both (pushing legs) can provide power.

Dual Phase or Split Phase power is also Single Phase because it’s a two wire Alternating Current (AC ) power circuit. In the US, this is the standard household power arrangement with two (Phase A, Phase B) 120V power wires (180 degrees out of phase with one another) like two bicycle pedals and one neutral wire. This arrangement provides (2) 120V and (1) 240V power circuits. 120V power flows (alternating) between either power wire (through the load) and the neutral wire. 240V power flows (alternating) between the two power wires (through the load).

This arrangement is used in most US households because of its flexibility. Low power loads (lights, TV, etc.) are powered using either 120V power circuit and high power loads (Water Heaters, AC Compressors) are powered using the 240V power circuit.

What does 3 (Three) Phase Power mean?

If you’re not electrically minded, think of 3 (Three) phase power like a three cylinder engine where three (pushing pistons) provide power.

Three Phase power refers to three wire Alternating Current (AC) power circuits. Typically there are three (Phase A, Phase B, Phase C) power wires (120 degrees out of phase with one another) and one neutral wire. For our purposes let’s consider a 3 Phase 4 Wire 208Y/120V power circuit. This arrangement provides (3) 120V single phase power circuits and (1) 208V three phase power circuit. 120V power flows (alternating) between any power wire (through the load) and the neutral wire. 208V power flows (alternating) between the three power wires (through the load).

Most US commercial buildings use a 3 Phase 4 Wire 208Y/120V power arrangement because of its flexibility. Low power loads (lights, computers, etc.) are powered using any 120V single phase power circuit and high power loads (Water Heaters, AC Compressors) are powered using the 208V three phase power circuit.

Most US industrial facilities use a 3 Phase 4 Wire 480Y/277V power arrangement because of its power density. Compared to single phase power circuits, three phase power circuits provide 1.732 (the square root of 3) times more power with the same current.

Using a 3 Phase power arrangement saves on electrical construction costs by reducing the current requirements, the required wire size, and the size of associated electrical devices. It also reduces energy costs because the lower current reduces the amount of electrical energy lost to resistance (converted to heat).