IEC 60309 (formerly IEC 309 and CEE 17, also published by CENELEC as EN 60309, and known as "commando" plugs) is a series of international standards from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purposes". They are also referred to as "pin & sleeve" connectors in North America or as "CeeForm" connectors in the entertainment industry. The maximum voltage allowed by the standard is 1000 V DC or AC; the maximum current, 800 A; and the maximum frequency, 500 Hz. The ambient temperature range is −25 °C to 40 °C. There is a range of plugs and sockets of different sizes with differing numbers of pins, depending on the current supplied and number of phases accommodated. Connectors generally are specified by the voltage and current ratings, general configuration (number of pins), and rotational alignment ("keying"). The fittings are popular in open-air conditions, as the connectors have a minimum IP44 weather-proofing rating. They are also sometimes used in situations where their special capabilities (such as high current rating or three-phase facilities) are not needed, to discourage potential users from connecting domestic appliances to the sockets, as 'normal' domestic plugs will not fit. The cable connectors and sockets are keyed and colour-coded, according to the voltage range and frequency used; common colours for 50–60 Hz AC power are yellow for 100–130 volts, blue for 200–250 volts, and red for 380–480 volts. The blue fittings are often used for providing weather-proofed exterior sockets for outdoor apparatus. In camping situations, the large 32 A blue fittings provide power to static caravans, whilst the smaller blue 16 A version powers touring caravans and tents. The yellow fittings are used to provide transformer isolated 110 V supplies for UK construction sites to reduce the risk of electric shock, and this use spills over into uses of power tools outside of the construction site environment. The red three-phase versions are used for three-phase portable equipment.
Standardization
IEC 60309-1 "Plugs, socket-outlets and couplers for industrial purposes" specifies general functional and safety requirements. IEC 60309-2 "Dimensional interchangeability requirements for pin and contact-tube accessories" applies to plugs and socket-outlets, cable couplers and appliance couplers with pins and contact tubes of standardized configurations. IEC 60309-3 "Particular requirements for plugs, socket-outlets, connectors and appliance inlets for use in explosive gas atmospheres". This standard was withdrawn in 1998. IEC 60309-4 "Switched socket-outlets and connectors with or without interlock" applies to self-contained products that combine within a single enclosure, a socket-outlet or connector according to IEC 60309-1 or IEC 60309-2 and a switching device, with a rated operating voltage not exceeding 1000 VDC or VAC and 500 Hz, and a rated current not exceeding 800 A. IEC 60309-5 "Dimensional compatibility and interchangeability requirements for plugs, socket-outlets, ship connectors and ship inlets for low-voltage shore connection systems (LVSC)" applies to a single type of plug, socket-outlet, ship connector and ship inlet, intended to connect ships to dedicated shore supply systems described in IEC/IEEE 80005–3. The standardization was originally done by the CEE (Commission internationale de réglementation en vue de l'approbation de l'équipement électrique), which became IECEE in 1985 (International Commission on the Rules for the Approval of Electrical Equipment) and is now part of the IEC. (This is the same body that produced the "CEE 7" series of domestic AC plugs.) The industrial sockets were standardized in the 1960s in the CEE 17 series that was adopted in the UK as BS 4343, and which are now the IEC 60309 standard.
Preferred current ratings and wire gauges The standard includes preferred current ratings and wire gauges for both International (deemed Series I) and North American (deemed Series II) applications. Series I preferred current ratings (in amps) are: 16, 32, 63, 125, 250, 400, 630 and 800, with wire gauges specified as mm2. Series II preferred current ratings (in amps) are: 20, 30, 60, 100, 200, 300, 350, 500 and 600, with wire gauges specified as AWG and circular mil.
Environmental protection
IEC 60309-2 connectors come in IP44 (splash-proof), IP67 (waterproof) and IP66/IP67 (jet-proof/waterproof) variants. In all cases, the rating applies when detached or mated, but not during the mating process. The more common IP44 variant features a spring-loaded hinged cap over the socket. When a plug is inserted, the cap hooks over a lug on the plug and retains it in place. Fixed connectors are usually installed angled downward to prevent water entering. The IP67 and IP66/IP67 variants include a gasket and a twist-lock ring which seals the two connectors together.
Dimensions Plugs have cylindrical connector pins arranged in a circle, with the earth pin 2 mm (0.079 in) larger in diameter than the other pins (used for line/neutral). This is surrounded by a circular shroud on the male connector, which fits into a matching recess on the female connector. The standard defines connectors with 3, 4 and 5 pins, but a non-standard variant with 7 pins (6 in a circle plus one in the centre) is commercially available; this can be used for star-delta starting of three-phase motors.
Pilot contact
Connectors rated at 63 A and 125 A may optionally feature a 6 mm pilot contact. Located at the centre of the connector, this smaller pin is shorter than the other pins. It is designed to make contact after all other pins when a plug is inserted, and to break contact before the others during disconnection. The pilot contact is used to switch off the load before separation. This is important because disconnecting under load can produce arcing, which may damage the plug and socket and pose a safety risk to the user. The pilot pin is located in the centre of main contact circle on 4 and 5-pin connectors. On 3-pin (2P+E) connectors, it is located on the contact circle opposite the ground pin. The other connectors are located 105° on either side of the earth pin, rather than 120° as in the smaller variants, to make room for the pilot pin.
Extra-low voltage variant The standard specifies an additional, different design for extra-low voltages up to 50 VAC and currents of 16 or 32 A. This resembles, but is larger than, the IEC 60906 DC connector.
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