What are special-purpose outlets?

The electrical sockets and outlets connect different electrical components to the main alternating current (AC) power supply in a building. These outlets allow the electrical equipment to be connected to the electricity grid. The equipment may be a heater, mixer, fan, air-conditioner, refrigerator, etc. Outlets are generally classified into two types. They are domestic and industrial outlets. The internal periphery of the electrical outlet consists of a loop of wire. When an electrical device is plugged in, the wire loop behaves as a closed circuit and allows electricity to flow into the electrical equipment so that it can be operated.

The domestic outlet sockets supply electricity of 120 volts (North America) and 220 to 240 volts (European countries). Moreover, the domestic outlets are manufactured following special codes like the national electric code (NEC) and also operate according to standards to ensure full protection to the users, these outlets are also known as special-purpose outlets or specialty outlets. These specialty outlets also provide child safety. While the industrial outlets have a power rating to make them suitable for the operation of heavy machinery and equipment such as electrical furnaces.

A 2 pin unearthed and 3 pin earthed socket.
CC BY-SA 3.0 | Image credits: https://en.wikipedia.org | Archenbridge Universities

Outlets are also known as receptacle outlets. However, a receptacle is a small unit having several slots which lets one connect plugs of electrical appliances, whereas a receptacle outlet is a complete module (box) having several receptacle units attached along with indicators and switches, this allows users to control various electrical units such as lights, fans, heaters, etc.

Here, in this article, a generalized outline has been provided regarding special-purpose outlets and their use.

Types of outlets

In this section, the various types of outlets have been discussed with their important features.

Ground fault circuit interrupter (GFCI) outlet

These kinds of outlets are specially used in areas where the chance of electrical shock is more such as kitchen, bathroom, garage, etc. These are smart outlets and can be easily identified by the presence of 'test' and 'reset' buttons present on the outlet periphery. These outlets have built-in electrical systems which constantly monitor the amount of electricity flowing through it and instantly disconnects the supply on detecting any imbalance in the electricity flow. Thus, this outlet protects individuals from severe electrical hazards.

A GFCI outlet
CC BY-SA 4.0 | Image credits: https://commons.wikimedia.org | Ben Kurtovic

Floor outlets

These outlets are installed on the floor rather than on the walls of the building, they can also be distributed through the floor periphery. These outlets are specially used in such places where installation of outlets is difficult due to construction constraints. These outlets have additional covers which allow covering of the outlets when not in use. This helps in protection from shocks and electrical risks.

Combination switch outlets

Combination switch outlets consist of a module that has both switch and an outlet to connect plugs of various appliances. The switch is provided for operating lights and fans, while the outlet is used for powering the appliances. These kinds of modules come in a standard electrical box, where the upper part houses the switches and the lower part houses the outlets.

Duplex wall outlets

The duplex wall outlets provide functionality features. These offer space for connecting two receptacles, i.e., it allows users to connect two electrical appliances at a time. The duplex wall outlets can also be wired to power different breakers and each of the sockets in these outlets can be controlled by switches.

Different appliances that need special-purpose outlets

In this section, some of the appliances are outlined that need special-purpose outlets for their operation.

Ovens and microwave ovens

These electrical appliances require much-rated power output and consume more current. Hence, they require special chords and special outlets with current ratings of 50 A with an internal circuit that can support 240 volts of potential difference.


With improved technologies and dedicated compressors, these appliances require a dedicated outlet that can support 20 A of current with a voltage rating of 240 volts.

Electrical dryers

These electrical appliances use four prongs which are according to the ideal recommendations. The circuits of these appliances need a 240 V electricity supply. This ensures dryers operate safely for various applications including cloth dryers.

NEC and safety issues

The NEC, i.e., National Electrical Code is a standard for the safe electrical installation of wirings and appliances, which is followed widely in the United States. The NEC is developed by National Fire Protection Association (NFPA). The electrical codes are intended to protect individuals from fire and electrical shocks. More than 5300 fire hazards annually are due to defective outlets and outlets which are installed without following any standards. There are some standards and rules issued by electrical standards organizations regarding various electrical installations in rooms of a typical residential building, they are:

  • Bathrooms: It is made mandatory to install GFCI outlets in every bathroom of a residential building.
  • Kitchen: All the plugs of the ovens, cooktops, and ranges should be connected to a 240-volt power source.
  • Living room: All the receptacles and plug points of bedrooms, living rooms, and divining rooms should not be further than 12 feet.
  • Laundry: The plugs of the dryers should be connected to a 240-volt outlet, with the washer and dryer having their own individual 20 A receptacles.
  • Outdoors: The outlets for outdoor application must be GFCI outlets. The appliances can also be connected to a GFCI breaker.

Advantages of special-purpose outlets

There are many advantages of special-purpose outlets, they are:

  • Using the correct outlet in right place protects from fire and electrocution.
  • They provide easy access to electricity.
  • The presence of adequate outlets avoids the use of overextensions cords.
  • Timely inspection and maintenance of the outlets ensure full protection safety.
  • Provides an overall module that houses different switches and outlets. These can be simultaneously used to control various electrical units and operate different appliances.

Context and Applications

This topic is widely used in different graduate and postgraduate degree courses of:

  • Bachelors in Technology (Electrical Engineering)
  • Bachelors in Technology (Electronics and Electrical Engineering)
  • Masters in Technology (Electrical Engineering)

Practice Problems

Q1. What is the work performed by an electrical professional?

  1. Plumbing
  2. Welding
  3. Electrical wiring
  4. None of these

Answer: Option c

Explanation: An electrician performs necessary electrical works such as electrical wiring and electrical planning for a building.

Q2. How a GFCI outlet can be identified?

  1. By the word 'neutral' written on the periphery.
  2. By the words 'test' and 'reset' written on the periphery.
  3. By the word' test' written on the periphery.
  4. By the word 'reset' written on the periphery.

Answer: Option b

Explanation: GFCIs are smart outlets, they control the flow of current and shuts off the current supply when they detect any unbalance. These outlets can be identified by 'test' and 'reset' written on their periphery.

Q3. How many prongs does a dryer have according to standards?

  1. Three
  2. Two
  3. Four
  4. Five

Answer: Option c

Explanation: A dryer such as the cloth dryer, is an electrical appliance that consumes 20 A of electricity with 240 volts. Hence according to standards, they must have four prongs.

Q4. What is the abbreviation of NEC?

  1. National Electronics Council
  2. National Electrical Code
  3. National Electronics Code
  4. National Electrical Council

Answer: Option b

Explanation: The National Electrical Code or NEC is an organization, which lays out standards for the installation of wirings electrical appliances.

Q5. According to standards what is the proposed distance for installation of outlets in a living room?

  1. 12 feet
  2. 10 feet
  3. 14 feet
  4. 8 feet

Answer: Option a

Explanation: According to standards, the outlets of the living room, bedroom, and dining room are to be installed at a distance of not more than 12 feet.

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