Here, we will understand the basics of both 15 Amp and 20 Amp Outlets. After that, we will find the differences between them by comparing 15 Amp vs 20 Amp Outlets against their typical use cases, power, wire sizes, and many other important parameters.
A Brief Note on Outlets
Receptacles or Outlets are the gateways to electrical power in a house. Before understanding the importance of a Receptacle, let us briefly understand how electricity reaches your home. The following explanation is an extremely simplified version of a typical electricity generation and distribution system. It all starts at the Power Plant. Be it thermal, hydro, or nuclear, irrespective of the source of energy all power plants generate alternating current at a potential of a few tens of kilovolts. Large transformers step this voltage up to a few hundreds of kilovolts to transmit it over large distances. As it reaches the local substations, the high voltage is stepped down to tens of kilovolts (33kV for industrial needs or 11kV for residential needs) and is then transmitted to different streets. Local distribution transformers (street transformers or pole transformers) step down this voltage to 120V. You will receive 120V (or 240V) from your utility and this reaches the main service panel. From the service panel, we distribute the electricity to different parts of the house by designing proper circuits. This is where the receptacles come into play. A Receptacle is an electrical device that helps us access the home’s electrical system with plug-based appliances and devices such as lamps, refrigerators, washers, ovens, computers, and many more.
What is a 15A Outlet?
A 120V 15A Outlet is one of the most popular and most common types of electrical outlets or receptacles for residential use. You can use appliances that draw power up to 1,800 Watts (120V × 15A = 1,800W) with a 15 Amp Outlet. This amount of power is sufficient for several low and medium-power appliances such as lamps, computers, TVs, power adapters for mobile phones, laptops or tablets, and other similar devices. As a result, you can find 15A Outlets in most parts of the house. Physically, 15 Amp outlets are available in polarized two-slot designs and also three-slot grounded designs. The two-slot polarized 15A Outlet consists of two vertical slots with one slot being longer than the other. Here, the longer slot is usually Neutral while the shorter slot is Hot. As a result of these uneven lengths, you can insert the plugs in only one orientation. This avoids accidental plugging of hot wire into the neutral slot or vice versa. The problem with this type of outlet is there is no ground connection. Hence, such outlets are phased out slowly in favor of the much better grounded 15A Outlet. In a grounded outlet, the two polarized slots remain the same. But in addition to that, there is a third “U” shaped slot that acts as the Ground slot. Previously, we used to get single outlet style 15 Amp receptacles. But most of them nowadays are duplex-style receptacles i.e., they have two outlets in the same strap. While Duplex Receptacles dominate the market you also get them in odd configurations with three or more contact devices.
Types of 15A Outlets
You can get the 120V 15A Receptacle in several variants. The Tamper Resistant (TR) is the recommended style for indoor use. The specialty of this type of receptacle is it has tiny shutters preventing any sharp object to be inserted into the slots. If you are familiar with GFCI and AFCI, then you know their importance. They are must-use outlets in critical places such as kitchens, bathrooms, and basements. You can get 120V 15A receptacles in both GFCI and AFCI styles. Advantages and Disadvantages:
Widely available Low cost Simple and low-cost solution for low-power appliances Not suitable for high-power appliances (for example oven, dryer, etc.)
What is a 20A Outlet?
The next popular electrical receptacle after the 15A variant is the 120V 20A Outlet. From the name itself, you can tell the difference between a 15 Amp Outlet and a 20A Outlet. While the 15A Outlet is suitable for power up to 1,800 Watts, with a 20A Outlet, you can theoretically draw up to 2,400 Watts (120V × 20A = 2,400W). This higher rating means you can use this outlet for high-power appliances such as refrigerators, ovens, blenders, toasters, etc. So, most kitchen appliances use 20A receptacles. Physically, the outline of the 20 Amp Outlet is very similar to that of a 15 Amp Outlet. But interesting things happen at the slots of the 20A Outlet. If you remember, the grounded 15A Outlet has three slots, two vertical slots for hot and neutral (hot is shorter than the neutral) and a round slot for ground. Coming to the 20 Amp outlet, the ground and hot slots are similar. But the neutral slot has a weird horizontal “T” shaped slot. If you are familiar with 20 Amp plugs, then you will know that the neutral pin on the plug is horizontal rather than vertical in the case of a 15A Plug. The vertical part of the “T” shape is the same size as a regular 15 Amp neutral slot. So, you can plug 15A plugs into the outlet as well. Another thing common between the 15 Amp and 20 Amp Outlets is the availability of GFCI and AFCI protection. You can get 120V 20 Amp outlets in both GFCI and AFCI styles.
Where Do We Use 20 Amp Outlets?
Most large kitchen appliances use these 20 Amp outlets. So, most of the outlets in a kitchen are usually 20 Amp ones. Also, if you have a garage where you use several heavy equipment and tools (drills, saws, air compressors, etc.), then you need 20 Amp outlets. Advantages and Disadvantages:
Can supply high power than 15 Amp outlets Suitable for all high-power kitchen appliances, power tools, etc. Fits both 20 Amp Plugs as well as 15 Amp Plugs The price of 20 Amp outlets is slightly more than 15 Amp counterparts In kitchen applications with high-power appliances, one circuit involves only one 20 Amp Outlet, usually with GFCI protection Needs thicker wire at 12 or 10 AWG compared to 14 AWG for 15 Amp Outlets
Differences: 15 Amp vs 20 Amp Outlet
Now that we have seen the basics of both the 15 Amp Outlet and the 20 Amp Outlet, let us make a comparison of the 15 Amp vs 20 Amp Outlet.
1. Physical Differences
While the overall physical dimensions of both 15 Amp and 20 Amp Outlets are the same, there is one important difference in the slots of the outlets. The 15 Amp Outlet has two vertical slots for hot (the shorter one) and neutral (the longer one) as well as a rounded “U” slot for ground. The 20 Amp Outlet has the same “U” shaped round slot for the ground. The hot and neutral slots are also the same. But there is an important difference between the neutral slot of the 20 Amp outlet. In addition to the long vertical slot, there is a horizontal section that forms the letter “T” but is rotated 90°. You can insert the 20 Amp Plugs as well as the 15 Amp Plugs into this slot. There is no way you can insert a 20 Amp plug into a 15 Amp outlet.
2. Power Capabilities
The maximum theoretical power you can draw from a 15 Amp Outlet is 120V × 15A = 1,800W and from a 20 Amp Outlet is 120V × 20A = 2,400W. But there is an unwritten rule that you shouldn’t draw more than 80% of the power from an outlet than it is capable of. If you take this as a guideline, then design your circuit in such a way that you draw a maximum of 1,440W from a 15 Amp outlet and 1,920W from a 20 Amp outlet to be on the safe side.
3. Suitable Circuit Breaker
An important point about the 15 Amp Outlet and the 20 Amp Outlet is the type of circuit breaker you can connect them to. If you are familiar with residential circuit breakers, then you will know that the two popular circuit breakers are 120V 15 Amp and 120V 20 Amp. With a 20 Amp Breaker, you can use both the 20 Amp Outlet and the 15 Amp Outlet. But with a 15 Amp Breaker, you can use only the 15 Amp Outlet. Another important thing is the number of outlets you can use simultaneously. Assuming all your receptacles are duplex-style receptacles, in a 20 Amp duplex receptacle, you can plug in two 20 Amp plugs, two 15 Amp plugs, or one each of 20 Amp and 15 Amp plugs. As we use a 20 Amp Breaker with a 20 Amp outlet, you have to plan the power draw from the individual outlets so that they don’t trip the breaker. For larger appliances (usually in the kitchen or garage), we recommend installing a single outlet 20 Amp receptacle for a corresponding 20 Amp breaker so that you don’t have to worry about the power draw calculations all the time you plug power tools or heavy equipment. In this way, all the 20 Amp receptacles have their dedicated breakers. Coming to the 15 Amp outlet, this is one of the most common and popular types of outlets in the majority of households. You can use it for lamps, small power tools, computers, televisions, and other similar electrical and electronic appliances.
4. Wire Gauge
Let us assume that your circuit consists of 20 Amp Breakers with only 20 Amp Receptacles and 15 Amp Breakers with 15 Amp Receptacles. In this case, the 20 Amp breaker and the 20 Amp Receptacle must use 12 AWG or 10 AWG wires while the 15 Amp breaker and the 15 Amp receptacle must use a 14 AWG wire. Even if you don’t plan to use the 20 Amp breaker and the corresponding 20 Amp receptacle to power up large appliances or use it with lamps or computers, you still have to use the 12 or 10 AWG wires to pass the inspection (and of course for safety reasons).
5. Typical Applications
The 15 Amp Outlet is suitable for powering small to medium power appliances such as lamps, TVs, computers, laptop chargers, small power tools, etc. As a rule of thumb, always follow the 80% rule i.e., do not draw more than 80% of the total power that a 15 Amp outlet (and the corresponding breaker) can handle. If you are using a 15 Amp outlet with a 20 Amp breaker, then you have to be very careful as the 20 Amp breaker will not trip until the power draw exceeds 20 Amps. The 20 Amp outlet on the other hand is quite common to use with large appliances such as refrigerators, blenders, dryers, and other kitchen and garage appliances. Consult with a certified electrician and make sure you install necessary GFCI outlets everywhere you need to, be it 15 Amp receptacles or 20 Amp ones.
6. Cost
This is one of the important reasons for the popularity of the 15 Amp breakers and outlets. They are much cheaper than their 20 Amp counterparts and you need less expensive 14 AWG wire. So, both the outlet and the corresponding wire are available at a low cost. Coming to the 20 Amp outlet, it is expensive when compared to a 15 Amp outlet. Also, you need an expensive 12 AWG or 10 AWG wire for wiring the circuits. You can save a lot by carefully designing your circuits so that you can divide lights and other low-power appliances with 15 Amp breakers and outlets and kitchen, garage, and other high-power appliances with 20 Amp breakers and outlets.
Conclusion
Electrical Outlets are an important part of a residential electrical system. They allow you to plug different electrical and electronic appliances and devices so that you can provide power to them. The 120V 15 Amp Outlet and 120V 20 Amp Outlet are the two most common types of receptacles in North American households. In this guide, we saw the basics of both the 15 Amp and 20 Amp outlet along with their pros and cons and also typical applications. After that, we made a simple 15 Amp vs 20 Amp Outlet comparison by taking some important parameters. We hope that this guide on common residential electrical outlets could help you understand the differences between 15 Amp and 20 Amp outlets. So, if you are planning for an upgrade or rewiring your house, then you will be in a better position to choose the right type of breaker, outlet, and also wire. If you feel we missed something or want us to add anything, do let us know in the comments. It will not only help us but also other readers. Comment * Name * Email * Website
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