Electrical Outlet Types

Considerations When Choosing an Outlet

There are various types of electrical outlets designed to match the requirements of your appliances, power tools and electronics. The most important factor, however, in choosing the right outlet is the wiring requirements. Most homes in the U.S. are wired with a combination of 15-amp and 20-amp, 120-volt circuits.

Because 15-amp receptacles can be used with 20-amp circuits, most of these electrical outlet types are the ones found in American homes. They have two slots and a U-shaped grounding hole. A 15-amp circuit is usually served by 14-gauge wire and is protected by a 15-amp circuit breaker or fuse.

20-amp receptacles have a horizontal slot branching off one of the vertical slots. Appliances, such as microwaves, often have 20-amp plugs and must be plugged into a 20-amp outlet. Electrical plugs designated as 20-amp will not fit into 15-amp outlets. A 20-amp circuit, protected by a 20-amp breaker or fuse, must be served by 12-gauge or 10-gauge wire.

The easiest way to determine whether a circuit is 15 or 20 amps is to look at the corresponding breaker or fuse in the breaker panel. Dedicated circuits are electrical lines that carry an electrical current to one single outlet. 20-amp receptacles are recommended for major appliances, so that they have an ample and consistent stream of power for safe operation.

When shopping for major appliances, you’ll also need to determine whether you need a 3-prong vs. 4-prong cord.

• 3-prong plugs are used for homes built before the year 2000.
• 4-prong plugs are used for homes built after the year 2000.

Tip: When you purchase a new appliance, a 4-prong cord is included with the appliance by default. If your home is equipped with a 3-prong outlet, you will need to purchase a 3-prong cord or connector adapter separately.

An electrical code is an official set of guidelines that specifies how various aspects of an electrical system should be installed. Most local residential electrical codes are based on the NEC—the National Electrical Code—a model code that provides guidelines on which local communities can model their own residential codes.

The Spruce / Michela Buttignol

Among other wiring installation details, the electrical code specifies how electrical outlets should be spaced and which types of outlets to use in general living areas, bathrooms, kitchens, and other locations. Far from being arbitrary, the electrical code as it relates to outlets is practical and can help do-it-yourselfers understand and wire their homes correctly.

One prime example of the code's real-world application is with outlet spacing in kitchens. In the kitchen, countertop outlets should be no farther than 48 inches away from each other. This spacing designation is based on the average length of electrical cord found on most small kitchen appliances. The intent is to prevent homeowners from stretching cords too far and creating hazards.

Code requirements for residential wall outlets may differ from one community to another since model building codes can be adopted and adapted as a community sees fit. Most, but not all, follow the recommendations of the national model code, the NEC. Be sure to check with your local building permit department for particulars.

Electrical Code Requirements for Outlets

• General areas: No point on the wall can be no more than 6 horizontal feet from a receptacle. Not required if the wall is 24 inches wide or less.
• Bathrooms: There must be a GFCI-protected receptacle at least 3 feet from the outside edge of the sink basin.
• Kitchens: Outlets can be no more than 48 inches apart, applicable for any wall 12 inches wide or more. Outlets cannot be more than 20 inches above countertops.
• TR receptacles: Tamper-resistant receptacles are required in many municipalities for locations 66 inches or lower on the wall. Not required behind large appliances or when the outlet is part of a light fixture or appliance.
• GFCI outlets: Required over kitchen counters, dishwashers, bathrooms, laundry rooms, unfinished basements, garages, many outdoor locations, swimming pools, and spas. This list is not exhaustive and may include other areas of the home.
• AFCI: Arc-fault circuit-interrupter protection is required for receptacles in many areas.
  

Outlet Spacing in General Living Areas

For code purposes, "general areas" are defined as rooms such as living rooms, family rooms, bedrooms, and hallways.

Article 210.52(A)(1) states:

Receptacles shall be installed such that no point measured horizontally along the floor line of any wall space is more than 6ft from a receptacle outlet.

This spacing is chosen so that a lamp, computer, television, or other appliance will never be more than 6 feet away from an electrical outlet.

Spacing outlets more frequently is allowed, but it is not required by code. If the space receives heavy use, such as with people charging phones or plugging in laptops, shorter spacing between outlets may be a good idea.

One exception to the rule: If the wall is less than 24 inches wide, an outlet is not required. Again, you are allowed to place an outlet in this space if you so choose.

Hallways more than 10 feet long must have at least one electrical outlet, preferably at the mid-point.

Outlet Spacing in Bathrooms

On bathroom walls, there must be a receptacle at least 3 feet from the outside edge of the sink basin. Generally, it is desirable to install the outlet above the countertop. But the code's 3-foot designation provides leeway in case this is not possible or practical. It's also good practice and safer to position the outlet to the side of a sink, not directly behind it. Outlets in bathrooms should be GFCI-protected and serviced by a 20-amp circuit. 

Tip

Installing a GFCI circuit breaker performs the same function as installing individual GFCI outlets within the bathroom. A GFCI circuit breaker protects all outlets downstream. So, even a non-GFCI outlet installed on a GFCI breaker circuit will safely trip off the GFCI breaker. GFCI breakers are not code-required. They do provide a cleaner installation than installing bulky individual GFCI units.

Outlet Spacing in Kitchens

In kitchens, electrical outlets should be placed no farther than 48 inches apart, so that no point on the countertop is more than 24 inches away from a receptacle. Any countertop 12 inches wide or more should have an outlet on the wall behind the countertop.

Outlets should not be positioned higher than 20 inches above countertops, with certain exceptions for physically disabled persons and for islands or peninsulas where this height rule cannot be met.

Amperage of Outlet Receptacles

General-purpose outlet receptacles should have a rating that is appropriate for the amperage of the circuit they serve. Generally, these household circuits will provide 15-amps or 20-amps of service, and the outlet receptacle rating should not exceed this amperage. Check the circuit's breaker in the service panel to find out whether it is 15 amp or 20 amp service, and choose receptacles appropriate to that rating.

There is no danger to installing 15-amp outlet receptacles on a 20-amp circuit (in fact, this is the standard practice), but under no circumstances should a 20-amp receptacle be installed on a 15-amp circuit.

A 20-amp receptacle is designed to accept the special plug on heavier-use appliances, and if such an appliance plugs into a 15-amp circuit, there is a danger of drawing too much power and overloading the circuit. A 20-amp receptacle is only installed on a 20-amp or larger circuit, and it is generally reserved for locations where a heavy-duty appliance is typically used, such as an outlet that might power a space heater.

Tamper-Resistant Receptacles

As an additional safety measure, most municipalities require tamper-resistant outlets for general areas of the home. These outlets are identified by the recessed letters "TR" on the face of the outlet. In tamper-resistant outlets, a spring-loaded gate within the outlet prevents young children from pushing objects such as knives into the outlet slots.

Tamper-resistant outlet receptacles are usually are not required for:

• Outlets located 66 inches or more above the floor
• Outlets behind large appliances that are difficult to move (such as a refrigerator)
• Outlets that are part of a light fixture or appliance

GFCI Protection Requirements

The electric code requires that outlet receptacles have GFCI (ground-fault interrupter) protection in certain areas of the home, including:

• Receptacles over countertops in kitchens
• Receptacles powering dishwashers
• Receptacles in bathrooms
• Receptacles in laundry areas
• Receptacles in unfinished basements
• Receptacles in garages and other accessible outdoor locations
• Receptacles near swimming pools, spas, and other water features

GFCI protection lowers the risk of shock when ground faults occur, and it can be provided in one of two ways: through the use of special GFCI circuit breakers that provide protection to the entire circuit; or with GFCI receptacles, which are specially designed to provide GFCI protection to a specific outlet, or to that receptacle as well as "down-stream" receptacles that are part of the same circuit.

Requirements for GFCI protection have gradually expanded with successive revisions to the NEC, and those requirements could possibly expand further in the future.

AFCI Protection Requirements

Since January 1 of 2014, the NEC has also required a different kind of protection for all 15-amp and 20-amp receptacles in general living spaces. This requirement calls for AFCI (arc-fault circuit-interrupter) protection for these receptacles.

AFCI protection senses and shuts down a circuit when an arc fault—minor sparking between wires or wire connections—occurs. AFCI protection reduces the chance of fire due to this sparking.

AFCI protection can also be provided in one of two ways: through special circuit breakers that protect all receptacles and devices along the circuit; or through special AFCI outlet receptacles that offer protection to one location only. Standard practice is to install AFCI circuit breakers to protect the entire circuit, but individual AFCI receptacles can be installed where circuit breaker installation is not practical.