Type M is used almost exclusively in South Africa, Swaziland and Lesotho.
This plug resembles the Indian type D plug, but its pins are much larger. Type M is a 15 amp plug, and it has three round prongs that form a triangle. The central earth pin is 28.6 mm long and has a diameter of 8.7 mm. The 7.1 mm line and neutral pins are 18.6 mm long, on centres spaced 25.4 mm apart. The centre-to-centre distance between the grounding pin and the middle of the imaginary line connecting the two power pins is 28.6 mm. The South African version of the M plug often has insulated sleeves on the pins to prevent accidental contact with a bare connector while the plug is partially inserted. Although type D is used in India, Sri Lanka and Nepal, type M is also used for larger appliances. Some sockets over there can take both type M and type D plugs. Type M is also used in Israel and the United Arab Emirates for heavy appliances such as air-conditioning circuits (in cases where wall-mounted units are plugged in to a dedicated socket) and certain types of washing machines. In the UK, type M is still pretty much the standard plug for theatre installations, despite efforts to move to the international blue- and red-coloured industrial CEE plugs.
Type N is used almost exclusively in Brazil.
The type N socket and plug are the official standard in Brazil. The plug consists of two pins and a grounding pin. There are two variants: the prongs of the 10 A version have a diameter of 4 mm and a length of 19 mm. The second version, rated at 20 amps, is used for heavier appliances and has 4.8 mm round pins, but also measuring 19 mm in length. The centres of the line and neutral pins are spaced 19 mm apart. The centre-to-centre distance between the earth pin and the middle of the imaginary line connecting the two power pins is 3 mm. Type N sockets were specifically designed to accommodate the ubiquitous type C plugs as well. Type N looks very much like the Swiss type J standard, but it is incompatible with it since type N has the earth pin closer to the imaginary line that connects the two power pins (3 mm instead of 5 mm).
Type N is actually based on the international standard 230 V household plug system, called IEC 60906-1. In 1986, the International Electrotechnical Commission published this standard, which was intended to become the common standard for the whole of Europe (and, by extension, all other regions with 230 V mains). Unfortunately, the effort to adopt it as a European Union standard was put on hold in the mid-1990s. Brazil had been using as many as 10 (!) different types of plugs and sockets, including the frequently used type C. In order to put an end to this proliferation of different socket and plug types, the Brazilian Association of Technical Standards (Associação Brasileira de Normas Técnicas (ABNT)) decided to standardize on IEC 60906-1. In 2001, this standard was adopted in Brazil as NBR 14136 and its implementation started in 2007. This Norma BRasileira 14136, however, is not completely identical to IEC 60906-1: the Brazilian standard has a pin diameter of 4 mm for the 10 A plug and 4.8 mm for the 20 A plug, whereas the original IEC 60906-1 standard only has one single pin diameter of 4.5 mm and a maximum current of 16 A.
Thanks to modern injection moulding technology, which did not exist when most other plug types were originally designed, the very recent type N standard is more compact, robust and safe than any other plug/socket system in the world.
Brazil’s standardization on one single plug and socket type, however, does entail some risks. Why? Simply because Brazil is one of the very few countries that does not have a standard voltage, but at the same time it has only one official type of socket! In other words, you cannot tell the difference between a 220 V and a 127 V socket! (Click here for an exhaustive list of all 27 Brazilian federative units and their respective voltages.) Most states use 127 V electricity, but a couple of them are on 220 V. This means that a 127 V hairdryer bought in the state of Minas Gerais will be destroyed when plugged into a compatible 220 V socket in Distrito Federal! Make sure you check out the local voltage before plugging something in! (Click here for a trick to know the local voltage.) It must be said, though, that many appliances sold in Brazil are dual voltage, but that’s definitely not the case for all of them.
Type O is used exclusively in Thailand.
The type O socket and plug, rated at 16 amps, are the official standard in Thailand. The plug system was designed in 2006, but its use is not widespread as yet. It is currently gradually being phased in. The standard is described in TIS 166-2549.
Type O consists of two power pins and an earth pin, which are round and have a 4.8 mm diameter. The power pins measure 19 mm in length, they have 10 mm long insulated sleeves and their centres are spaced 19 mm apart. The earth pin has a length of 21.4 mm. The centre-to-centre distance between the grounding pin and the middle of the imaginary line connecting the two power pins is 11.9 mm, which is exactly the same distance as in type B plugs. This is not a coincidence, since the hybrid version of this socket was originally designed to accommodate plug types A, B, C and O. In the long run, compatibility with American plugs is planned to be phased out, since the electrical network in Thailand operates at 230 V. Although they look similar, type O plugs are not interchangeable with the Israeli type H or the Danish type K power plugs. However, there is a very unsafe compatibility between type O sockets and type E/F plugs, which is why the Thai Government banned the sale of appliances fitted with E/F plugs. When used in Thailand, an E/F plug will not be grounded and when such a plug is partially pulled out, you will be able to touch the prongs while they are still live!
Can somebody please enlighten me as to why on earth a country would develop a whole new kind of plug and socket system when there are several alternatives available? Standardising on the international type N (or, for that matter, another safe and earthed plug system that is compatible with type C, such as F or E) is of course self-evident. As the Thai Government is going to phase out compatibility with plug types A and B anyway, why haven’t they adopted the type N standard, while at the same time allowing for a period of transition where hybrid B/N-receptacles as well as type N sockets may be installed? This is absolutely mind-boggling!