The simple task of specifying an ac electrical plug takes on numerous intricacies in equipment destined for different parts of the world.
Look at an electrical outlet outside the U. S. and you’ll probably see an unfamiliar plug pattern. There are 18 different plug patterns used around the world. In addition, countries around the world use different ac mains voltages and frequencies. North America, part of South America, and a few other countries that run on 60 Hz. Most of the rest of the world runs on 50 Hz. However, some countries, such as Japan, run on both. While the voltages in most industrialized countries are typically 120 or 230 Vac, voltages can run anywhere from 100 to 250 Vac. Again, some countries use multiple voltages.
When configuring electrically powered equipment for use outside the U. S., cutting off the “wrong” plug and rewiring the “right” plug or using an adapter does not solve the problem. Once you change the cord, as when rewiring the “right” plug onto it, the cord loses its regulatory approval — which could also affect the approvals on your equipment. Use of country-specific adapters is fine for traveling, but they are not recommended for use on a piece of industrial equipment; the adapters are not approved, so your cord and equipment may lose approvals.
All developed countries and many of the developing countries have electrical safety standards. As a result, most have electrical testing agencies. The U. S. has several, including Underwriters Laboratories and CSA International; Germany has VDE; Sweden has Semko, and so on. Most developed countries require some sort of a third-party test and approval before equipment can be sold internally. Many European countries will accept VDE approval on parts used there. In most European cases, the national standard will simply be a translation into the local language of the applicable International Electrotechnical Commission (IEC) or Cenelec document. Any deviations are noted in the front of the publication. UL and CSA have adapted some IEC standards but, for the most part, their standards are independent of IEC and Cenelec.
Plugs and sockets can be categorized by their class and polarization. Class I plugs and sockets have the ability to provide grounding. The grounded plug and socket must have at least three pins or contact points. Class II plugs and sockets have only two electrical contact points, line and neutral, and use two-wire cables.
A polarized plug-and-socket configuration has two meanings. The first is electrical polarization. In this situation, there is an assigned method of wiring the plug or receptacle. The wiring is done so the connection between the line wires and the neutral wires on the plug and receptacle always make contact. This polarization pattern provides a method of controlling the entry of electricity into the equipment.
The second form of polarization is pin polarization. Pin polarization means there is only one way to insert a plug into the socket. This is based on the alignment of the pins in the plug to the holes in the receptacle or socket. Some plug patterns, such as the Schuko, are neither plug nor pin polarized.
North American plugs
The North American plugs, connectors, and receptacles are described in standards published by the National Electrical Manufacturer’s Association (NEMA) in the U. S. and Canadian Standards Association (CSA) in Canada. The standards identify unique pin and receptacle configurations based on amperage and voltage ratings. Both straight blade and locking configurations are included in the standards.
An accompanying chart shows the different pin configurations. Notice that the blade position changes or is a different shape to prevent accidentally plugging a 30-A plug into a 15-A receptacle. The NEMA 5-15 straight-blade configuration is used most often in the U. S. and Canada.
The NEMA pattern and numbering system is made up of four main identifiers. The first can be a blank space or have the letter L. This determines whether the connection is a straight or locking blade device. For example a 5-15 plug means the blades are straight, but a L5-15 plug denotes a locking version.
The second identifier is a number. The first digit listed determines the voltage rating. The 5 in a 5-15 corresponds to the voltage rating of 125 Vac, while the 6 in 6-15 identifies a rating of 250 Vac. The rating given is the highest voltage allowed for a device by the standard.
The third identifier is also a number and it identifies the amperage rating for the device. A 5-20 has a rating of 20 A. The amperage rating, like the voltage rating, is the highest amperage the standard allows for use with the device.
The fourth identifier is a letter. The identifier determines whether the device is a plug, P, or a receptacle/outlet, R. Therefore, an L5-15P is a locking, 125-V, 15-A plug. A 5-20R is a straight-blade, 125-V, 20-A receptacle or outlet. If there is no letter in the fourth position, it is assumed the device is a plug.
Hospital-grade plugs and sockets are subject to special UL and CSA requirements. Hospital-grade plugs, connectors, and receptacles shall be marked with the phrase “Hospital Grade” and carry the “green dot,” signifying they have been designed and tested for grounding reliability, assembly integrity, strength, and durability. Specifically, they meet or exceed the requirements of UL Standard 498 and CAN/CSA 22.2 no 42. Cords are subject to UL 817 and CSA C22.2 no 21. UL 60601-1 refers to patient-care equipment and patient vicinity. Currently the standard only allows the NEMA 5-15, 5-20, 6-15 and 6-20 straight-blade devices to be marked “Hospital Grade.”
It should be noted that North American NEMA plugs, which are pin polarized and can be electrically polarized, are also used in Mexico, Japan, parts of Korea, Taiwan, Central America, Colombia, Venezuela, Ecuador, and on the west coast of South America. These countries are not obligated to follow or utilize our ratings systems and often don’t. The electrical systems in developing countries are usually ungrounded.
Plugs and sockets in Japan and Europe
The Japanese plug and socket, at first glance, looks identical to the North American NEMA 5-15 standard. However, the Japanese system, which is specified in JIS (Japanese Industrial Standard) 8303, incorporates tighter dimensional requirements, different marking requirements and mandatory testing and approval by the Japanese testing agency.
Japanese mains frequently do not provide for grounding; grounding is made to the wall socket through use of an adapter. As a result, Class I grounded sockets are used less frequently in Japan than in the U. S. and Canada. Most appliances sold in Japan use a Class II ungrounded plug. Class I grounded appliances should be sold with a ground wire adapter. This can be accomplished by either the use of a two-pin plug with a grounding wire attached or by using a grounding adapter that has PSE (Product Safety Electric Appliance and Materials) approvals.
DENA is a mandatory national law administered by Japan’s Ministry of Economy, Trade, and Industry. Cords, plugs, and sockets must carry the PSE approval mark unless they are medical-grade plugs — in which case they carry the JIS approval. Japan also has a medical-grade standard called JIS T1021, but the hospitals make the final decision on whether or not they want to use medical-grade plugs.
Japanese wire sizes and current ratings are different than those used elsewhere in the world. Japan is at 100 V and 50 and 60 Hz. It would be advisable to check the frequency before shipping your equipment to Japan.
Now let’s turn to Europe. The official plug standard in the U. K. since 1962 is BS 1363. BS 1363 requires a three-pin fused plug with a partial insulated line and neutral pins for all connections to the power mains. This includes Class II plugs. The ground pin is slightly longer than the other two pins, so it can open the shuttered line and neutral contacts in the outlet. British power outlets incorporate shutters on the line and neutral contacts to prevent someone from pushing a foreign object into the socket. As a result, the Class ll plugs have a “dummy” ground pin to open the shutters.
Class l plugs in the U. K. are rated from 3 to 13 A (depending on the fuse, 250 Vac). Class ll plugs are rated at 2.5 A, 250 Vac. The old BS 546 is still used in some extremely specific applications. The 15-A plug is still used in some theaters and as a result is nicknamed the “Stage Plug.” The 2 and 5-A versions can be used in table-lamp-type applications in some hotels. And, for the most part, the old BS 546 standard is used in other countries, such as India and South Africa.
The U. K. has a unique wiring system. Most of the world has linear wiring, which starts at the circuit-protection devices or supply point and goes straight out to the lighting or outlets and stops at the last outlet or light. The U. K., however, uses a ring system where the circuit starts at the supply point and goes out to the lighting or outlets and then at the last device goes back to the power supply to form a continuous ring. Because electricity can be supplied from both directions, the outlets are always hot. As a result, the British plug has a fuse in the plug. The fuse in the plug must meet the BS 1363 standard.
In addition to the fuse in the plug, most equipment must also provide overcurrent protection. So when you are designing equipment for the British market, plan on including circuit protection unless you are advised differently by one of the British safety agencies.
The British do have a special plug and socket for protected data circuits. The plug and socket incorporate a special T-shaped ground pin, which allows the data circuit-plug to connect only to a protected outlet. The outlets exclude all other plugs, so you cannot accidentally plug a vacuum, for example, into the protected circuit and put unwanted “noise” on the circuit. It is important to note, however, that the data-circuit plug does not carry any approvals. But it meets the BS 1363 standard.
The British standard does allow for one plug adapter, the Euro-to-UK adapter. This adapter lets the user attach the Euro plug to the adapter plug to use the equipment in the U. K. The Europlug converter plug is a Class ll plug. The three-pin converter, with the “dummy” pin in the ground position, opens up so the two-pin Euro plug can sit inside the converter. This converter meets the BS 5733 standard.
The British plug is used in Ireland, Hong Kong, Malaysia, Singapore, Cyprus, Malta, and many former British colonies. Ireland, Malaysia, and Singapore have an equivalent standard to the BS 1363. The Association of Short Circuit Testing Authorities (ASTA) requires that its mark be molded into the plug.
Electrical standards in the rest of Europe differ from those of the U. K. The Class I Continental European plugs and outlets are designed to the CEE (Commission on Rules for the Approval of Electrical Equipment) 7 standard. The CEE 7 refers to publication number 7. A slash and second number designate a subsection in the publication that pertains to more details about acceptable modifications to the CEE 7 plug pattern.
The most common plug used in Europe is the CEE 7/7 or Schuko plug, which is dual grounded. It can be grounded by the two metal strips on the side, and it has a ground pin receiver on the face of the plug. As a result, it can plug into both the CEE 7 outlet, which has grounding strips on the side of the socket, or the variation of the CEE 7 outlet, which has a grounding pin on the face of the outlet. These are used in France and Belgium. This plug has two 4.8-mm round contacts on 19-mm centers.
Though the Schuko plug pattern is used in many European countries, some countries’ approvals may vary slightly. The Schuko plug will fit the 10-A sockets in Italy and Denmark; however the plug will not be grounded. As a result, we strongly recommend the use of Italian and Danish plugs. The CEE 7/7 plug can be used in France and Belgium. The use of the CEE 7/4 is not allowed; the French and Belgians use a socket with a grounding pin.
The Schuko plug can be used in Germany, Austria, The Netherlands, Sweden, Norway, Finland, Russia, Afghanistan, Egypt, and the Republic of Korea. In Europe, Class I cords are rated up to 16 A. The Europlug is used for Class II applications and is rated at 2.5 A. Countries that use the Schuko plug do not have a medical standard. However as mentioned earlier, Sweden does not allow rewireable plugs to be used in medical applications. The Schuko plug is rated for use up to 250 V and 50 Hz. This plug is neither electrically nor pin polarized
France, Belgium, Poland, Czech Republic, and Slovakia use a variation of the CEE 7 socket. This socket has a male grounding pin on its face. In addition, France and Belgium require safety shuttering on all sockets. The CEE 7 variation is not compatible with the CEE 7/4 plug but is compatible with the CEE 7/7 plug. The socket is rated at 16 A, 250 V, 50 Hz and is pin polarized.
The Europlug is a Class II plug that is described in CEE 7/16. This plug is rated at 2.5 A and has two 4.0-mm round contacts on 19-mm centers. It will mate with any socket that accepts 4.0 to 4.8-mm round contacts on 19‑mm centers. As a result, this plug is used in more countries than the Schuko plug, including Denmark and Italy. Each of these countries uses a specific plug that differs from the Schuko plug, but their sockets accept the Europlug. The Europlug is rated up to 250 V and 50 Hz, and, like the Schuko, this plug is neither pin nor electrically polarized.
The Swiss plug is governed by Schweizerischen Elektrotechnischen Vereins (SEV) 1011:1999. However, there has been a change to the standard which will be enforced December 31, 2012. The new standard, SEV 1011:2009, requires line and neutral pins be partially insulated. This change only affects the 10-A plug.
The Swiss plug is quite similar to the Europlug and Italian plug. However, the Swiss plug has a grounding pin that is slightly higher than the line and neutral pin. The 10-A plug has round pins while the 16-A plug has slightly square pins, to prevent accidentally plugging a 16-A plug into a 10-A outlet.
Like most of Europe, Switzerland does not have a medical standard. Class I plugs are rated at 10 and 16 A there. Switzerland uses the Europlug for Class II applications at a 2.5-A rating. The Swiss plug is rated up to 250 V and 50 Hz and is pin and electrically polarized.
The Danish plug pattern is described in Danmark’s Elektriske Materielkontrol (DEMKO) publication, Afsnit 107-2-D1. This plug pattern is unique to Denmark. The pattern is similar to that of the Schuko plug, but instead of grounding clips on the side, it has a short grounding pin on its face. Though the Schuko plug fits the Danish socket, it is not recommended for use in Denmark because the plug would be ungrounded and could cause serious safety hazards and liability exposures for the manufacturer. This makes it important to use the Danish plug on equipment exported to Denmark.
The Denmark plug is rated up to 230 V and 50 Hz and is pin polarized. The Danish Class I plugs are rated at 13 A, and Denmark uses the Europlug for Class II plugs at a 2.5-A rating. Like the U. K., Denmark has a data plug for equipment that is especially sensitive to power spikes and surges. The pins on a data-circuit plug are flatter and not round. Denmark also does have a medical-grade standard, as outlined in standard SB 107-2-D1, which was published at the end of 2003. The plug has a round line pin and a flat neutral pin.
The Italian plug pattern is three pins in a row with the middle pin ground. The Class I plugs are rated at 10 and 16 A. The 16-A pins are larger than the 10-A pins to prevent a 16-A plug from going into a 10-A socket. Like many European countries, Italy uses the Europlug for Class II applications. Italy does not have a medical standard. Its plug is rated up to 250 V and 50 Hz and is not pin polarized.
Australia/New Zealand’s plug-and-socket system is described in standard AS/NZS 3112. Australia uses 230 V and 50 Hz, and plugs there are pin polarized. Australia has several state electric-testing agencies, and they usually accept each other’s test results. The Australian agencies also accept component approvals from SNZ, the New Zealand electrical testing agency, and vice versa.
The Class I plugs and sockets are rated at 10, 15, and 20 A, with a bigger pin size for larger amperages. This way, you cannot plug a 20-A plug into a 10-A socket. The Class II cord set is rated at 2.5 A. The line and neutral pins are partially insulated to protect against accidental shock while inserting and removing the plug.
Medical equipment used in Australia must meet AS/NZS 3200 Series. However, there are no special requirements for cord sets, only preferences. Besides meeting the normal standards of Australian cord sets and power cords, hospitals prefer clear plugs and connectors and orange flexible cable.
China’s standards agency is the China Quality Certification (CQC). All plugs, sockets, connectors, and receptacles must be approved by the CQC and bear the CCC (China Compulsory Product Certification) mark. The plug-and-socket pattern for use in China is specified in publications GB2099-1 and GB 1002-1. The Chinese use a 2.5-A plug for Class II. Class I products use 10 and 16-A plugs.
The Chinese plugs resemble the Australian plug pattern except that the contact pins are 1-mm longer, the body dimensions vary slightly, and the line and neutral pins are not insulated. The line and neutral on the Chinese plug are wired the same as the Australian plug. China also does not have a medical-grade standard. China uses 220 V and 50 Hz and its plug can be electrically and pin polarized.
The India/South Africa plug is patterned after the old British 546 standard. However, plugs are approved under the Bureau of Indian Standards (BIS) and the South African Bureau of Standards (SABS). The plug pins are large and round, with the line and neutral pins partially insulated for safety. As with those in many European countries, the outlet is shuttered. Like much of the world, neither India nor South Africa has a medical-grade plug standard.
There is going to be a slight change to the South African Standard with regard to the length of the insulation on the line and neutral pins and a 0.03-mm change to the layout of the pins. At this time it’s not clear when the changes will become mandatory.
The same plug is used in South Africa as in other parts of Southern Africa, Ghana, Kenya, Nigeria, India, the Middle East, Nepal, parts of Asia, and the Far East, where countries were electrified by the British. South African Class I plugs are rated at 6, 10, and 16 A, and Class II plugs are rated at 2.5 and 6 A.
A point to note is that India uses 230 V and 50 Hz while South Africa uses 220 to 250 V and 50 Hz. The South African plug is pin polarized.
The countries in South America engaged in significant international trade are Argentina and Brazil. Instituto Argentino de Normalizacion (IRAM) is the standards agency for Argentina, and IRAM 2073 defines the standard plug. Argentina uses a 2.5-A plug for Class II applications and a 10-A plug for Class I applications. The Argentine plug looks similar to the Australian plug, with only slight differences. The Argentine pins are 1-mm longer than the Australian plug’s, the body dimensions change slightly and, most importantly, the wiring differs. The positions of the line and neutral contact pins are reversed from those of the Australian plug. In addition, Argentina does not have partially insulated neutral and line pins. For this reason, manufacturers must take great care when exporting equipment to both Australia and Argentina.
Argentina does not have a designated medical-grade standard. It also uses 220 V and 50 Hz, and its plug is pin polarized.
The Brazilian NBR 14136:2002 is the new standard for Brazilian plugs and receptacles, which went into effect on all new equipment sold in Brazil as of Jan. 1, 2010. This standard is based on the international IEC 60906-1 standard, developed to encourage countries to adopt one plug and receptacle for global use. So far, Brazil is the first country to adopt this standard. Before this, Brazil used a “universal” receptacle that accepted both the North American and Europlug plugs.
The new Brazilian plug is similar in looks to the Swiss plug, but they are not interchangeable. The Brazilian plug is wider, the plug face is slightly larger, and the pins on the Brazilian plug are closer together. Class I plugs in Brazil are rated at 10 and 20 A. The new standard does not include a medical-grade plug. Brazil also uses 110 to 220 V and 60 Hz and its plug is pin polarized.
Finally, Israel’s standard plug pattern is defined in SI-32 and is unique to Israel. The Class I Plug is rated 16 A and is used for all Class I applications from 2.5 to 16 A. The Europlug is used for Class II applications. Israel does not have a medical standard. The Israeli plug is rated up to 250 V and 50 Hz and is pin polarized.