Last updated: 10 August 2020

Universal wall sockets

There are as many as 15 commonly used types of domestic plugs in use worldwide. Most countries have adopted one standard plug and socket system, but oddly enough, some others have never bothered to settle on a standard. They are now stuck with various incompatible systems, imported from abroad. In order to solve the problem, some of these countries have taken a short-sighted approach by allowing so-called “universal” wall sockets to be installed in properties, but such power outlets often violate basic safety standards (more about that below).

Click here for a global map showing the spread of the different plug types used around the world.

Click here for a detailed list of the countries of the world with their respective plug and outlet types, voltage and frequency.




Four commonly used multi-standard wall outlets

There are many universal wall sockets on the market, but here are four widely used types.

Universal socket

Type A C

  • the most frequently used type of hybrid socket worldwide
  • compatible with the two internationally most widely used plug types:
  • not grounded

Universal socket

Type A C I

  • a narrow variant of the previous type, but with the addition of an additional type I outlet
  • common Chinese universal socket
  • compatible with the following plugs:
  • not grounded when used with types A & C
  • grounded when used with type I

Universal socket

Type A B C D E F G I O

  • compatible with the following plugs:
  • not grounded when used with types A & C
  • grounded when used with types B, D, G, I & O
  • not grounded (although it ought to be!) when used with types E & F

Universal socket

Type A B C D E F G I J K L O

  • a narrow variant of the previous type, but with the addition of type J, K & L compatibility
  • probably the wall outlet that comes closest to being truly “universal”
  • compatible with the following plugs:
  • not grounded when used with types A & C
  • grounded when used with types B, D, G, I, J, K, L & O
  • not grounded (although it ought to be!) when used with types E & F




Why are universal wall outlets such a bad idea?

Due to the lack of a national standard and the wide range of different plugs and sockets used within their borders, some countries allow universal wall outlets to be installed in properties. Although this may seem like the perfect solution (one socket for a huge variety of plugs), a universal socket is not the answer. But why not?

Universal outlets can be outright dangerous for a number of reasons, such as exposure of live pins, lack of required earth ground connection, voltage mismatch or lack of protection from overload or short circuit. Universal sockets never meet all technical standards for durability, plug retention force or temperature rise of components.

  • Exposure of live pins

Universal outlets have a serious risk of electric shock because it is often possible to touch live pins while the plug is inserted into the mains socket. Some plugs (types C, G, I, J, L, M, N, O) have partially sleeved line and neutral pins to ensure that the metal cannot be touched when the plug is partially pulled out. The Continental European plug types E/F do not have sleeved prongs, but safety relies on the plug being inserted into a recessed socket. As universal sockets are not recessed, there is nothing to prevent a person from accidentally touching a live pin on a partially inserted plug.

Incidentally, this risk of electric shock is even possible with the official – and notoriously unsafe – American sockets (types A & B), but that is a different story…

  • Poor contact and insufficient mechanical stability

Receptacles are always designed to make complete electrical contact with the pins of the plug. Since the contacts in a universal socket are designed to accept a variety of sizes and shapes, they often only touch the prongs at a couple of points. A poor contact can result in arcing or overheating, which may result in a fire.

Another function of an outlet is to securely hold the plug, but the overlarge holes and poor contacts in a universal socket prevent this from happening. In addition, some plugs (such as types E/F and N) rely on the socket recess for additional stability, but universal receptacles are never recessed. This explains why plugs sometimes fall out of universal sockets during use.

  • Lack of earth ground connection

Unlike, for instance, American-style type B plugs, European E/F plugs do not have an earth pin. Instead they either need a prong protruding from the face of the socket or side contacts (i.e. two sprung metal strips on the inside edge of the recessed socket which make a friction connection with similar metal strips on the sides of the plug body).

Neither of these exist in a universal receptacle, since their presence would prevent other types of plugs from being used. So, universal sockets will accept type E/F plugs, but they will not be earthed. In the event of a short circuit, this could be fatal.

  • Voltage mismatch

Voltage mismatch is another issue. Different mains voltages are used throughout the world. Most of the world uses 230 V, while in North America the voltage is 120 V. If a device that is intended for 120 V is plugged into a 230 V socket, the higher voltage will cause overheating and may result in a fire.

Fortunately, almost all modern electronic devices (such as laptops or phone chargers) are multi voltage and accept both 100-127  V and 220-250 V rated input power.

  • Lack of built-in safety shutters

The socket on the right is fitted with shutters; the one on the left isn’t.

Many plug standards require pin holes to be shuttered to prevent children from poking objects into the socket.

The internal shutters of type E sockets, for instance, are only opened when the two pins of the plug are simultaneously inserted into the socket; the two live holes of type G outlets are only unlocked when the central earth pin is inserted, etc.

Some universal sockets have no shutters, which allows plenty of space for a child to poke objects into the live contacts.

  • Wrong insertion of plugs

The overlarge apertures of a universal socket allow some types of plugs to be inserted into the wrong holes. It goes without saying that this can result in a short circuit or worse… The picture shows a type C plug that is inserted into the wrong contacts.



Check out all plug types used around the world