Residential voltage in the USA and Canada is 120 / 240 volts AC. Power enters the dwelling’s main electrical panel from a power company transformer as two 120 volt lines with phases that are 180 degrees apart.
120 and 240 volts (along with neutral and ground) is then distributed to outlet boxes (switch, receptacle, light fixture, etc) throughout the dwelling. 110, 115, 120, 125, 130, 220, 230, 240, 250 volts, what are all these different voltages? Nominal voltage -120 volts & 240 volts are the standards to designate a voltage class for residential buildings. All other voltages are high or low voltage ratings of light bulbs, appliances, electronics etc.
Higher voltage ratings of 125, 130, 230, and 250 volts are for switches, receptacles, bulbs, and certain loads. These ratings indicate the upper limit of voltage for a device or load to operate properly under normal conditions.
Lower voltage ratings of 110 , 115, and 220 volts are for loads (appliances, motors, etc). These ratings indicate the lower limit of voltage for proper operation under normal conditions. Residential electric ranges, electric dryers and central air conditioners usually need 240 volts to operate.
240 volts is achieved when combining two sources of 120 volts of different phases (A and B phases). B phase current flows in the opposite direction as A phase. When A phase voltage peaks at +170 volts, B phase is at -170 volts. For electrical beginners, understanding the differences between voltages is a common issue, and sometimes can be a very confusing task that can lead to endless debates.
Which one is better? 24-volt or 12-volt? Which one is safer between 120-volt and 240-volt? What do all those numbers even mean ? In this article, we will discuss the differences between all the common voltages used in both DC and AC applications, and the advantages as well as disadvantages of each.
To understand the fundamentals of electrical voltage better, let's imagine that our wire is a water pipe, and the electrical current is the water current.
What then, is the electrical voltage in this water pipe assumptions? It is the water pressure inside the pipe. In fact, voltage is also often called electrical pressure or electrical tension.
Check out this history of the term 'voltage' by Think For Yourself. If we remember our junior high physics, pressure affects the speed of the water current entering the pipe. The harder the pressure, the slower the water speed, and the less water entering per any given time.Understanding that basic principle, the higher the voltage, the less current will be entering the wire per any given time to achieve a certain power.Thus, we came into the famous equation:.
Where P is power, measured in Watts, kiloWatts, or megaWatts, I is the electric current measured in ampere, and V is voltage.So, resuming our analogy of water, what changes as the voltage change?In water, the higher the pressure, the more harmful it is to the human body. Is that the case with voltage? Apparently, yes, the higher the voltage, the more dangerous it will become when electrocution occurs.In DC voltage applications, 12-volt and 24-volt are the one commonly used.
48-volt is a bit less common but is still widely applied in today's DC voltage applications.On the other hand, in AC applications (the electricity supplied by the power company), 120-volt is the standard in U.S. and North America, while 240-volt is the standard for almost the rest of the world.So, is the U.S.
electricity safer than the rest of the world? And is 12-volt safer than 24-volt? The answer is a bit more complicated than that, so let's dig deeper. We have discussed how generally lower voltage is safer during electrocution (safer doesn't mean entirely safe, reader's discretion is advised.) What other effects will a higher, or lower voltage bring to our electrical system as a whole?
Here are some notable ones:. Wire Size: As discussed, the lower the voltage, the more currents will be needed to power up an appliance or a light bulb. As electrical current generates heat, this will mean that you will need a thicker wire that can withstand that heat. In short, the cost for your wirings will be significantly higher.
Efficiency: Conductors (the metal inside your wires that conducts electricity) generally is more efficient when operating at higher voltage.