Gender of connectors and fasteners
In electrical and mechanical trades and manufacturing, each half of a pair of mating connectors or fasteners is conventionally designated as male or female, a distinction referred to as its gender. The female connector is generally a receptacle that receives and holds the male connector. Alternative terms such as plug and socket or jack are sometimes used, particularly for electrical connectors.
The assignment is a direct analogy with male and female genitalia. The part bearing one or more protrusions, or which fits inside the other, is designated male, while the one with the corresponding indentations, or fitting outside the other, is designated female. Extension of the analogy results in the verb to mate being used to describe the process of connecting two corresponding parts together.
In some cases, the gender of connectors is selected according to rigid rules which enforce a sense of one-way directionality. This is done to enhance safety, or ensure proper functionality, by preventing unsafe or non-functional configurations from being set up.
In terms of mathematical graph theory, an electrical power distribution network made up of plugs and sockets is a directed tree, with the directionality arrows corresponding to the female-to-male transfer of electrical power through each mated connection. This is an example where male and female connectors have been deliberately designed and assigned to physically enforce a safe network topology.
In other contexts, such as plumbing, one-way flow is not enforced through connector gender assignment. Flows through piping networks can be bidirectional, as in underground water distribution networks which have designed-in redundancy. In plumbing situations where one-way flow is desired, it is implemented through other means, and not through male-female gender schemes.
Early mentions of the metaphor
The Talmud describes arrow heads and mating shafts as potentially being either male or female, depending on their construction, i.e. a prong on a male arrow head fits into a hollowed out shaft and vice versa. This is owing to a prohibition on a female shaft, from its susceptibility as a receptacle for impurity, for use as s'chach.18th-century dictionaries and encyclopedias mention male and female screws or cochleae. A 1736 builder's manual mentions screw genders as metaphors for convex and concave shapes:
Mechanical fasteners
In mechanical design, the prototypical male component is a threaded bolt, but an alignment post, a mounting boss, or a sheet metal tab connector can also be considered as male. Correspondingly, a threaded nut, an alignment hole, a mounting recess, or sheet metal slot connector is considered to be female.While some mechanical designs are one-time custom setups not intended to be repeated, there is an entire fastener industry devoted to manufacturing mass-produced or semi-custom components. To avoid unnecessary confusion, conventional definitions of fastener gender have been defined and agreed upon.
Modular construction toys
Several common construction toys embody gendered mechanical interconnections. For example, the canonical Lego plastic blocks have female indentations on the lower surface and male bosses, or protrusions, on the upper surfaces. Meccano and Erector have many gendered connections, starting with the nut-and-bolt fasteners they use frequently.Stickle bricks, using interlocking plastic protrusions, are effectively genderless. Lincoln logs use a very simple form of genderless connections. Kapla or KEVA planks are extremely simple genderless systems interconnected only by gravity.
Mathematicians have begun to classify well-known construction sets using group theory to study the combinatoric possibilities of structures that can be built.
Plumbing
In plumbing fittings, the M or F usually comes at the beginning rather than the end of the abbreviated designation. For example:- MIPT denotes male iron pipe thread;
- FIPT denotes female iron pipe thread.
[|Hermaphroditic] connections, which may include both male and female elements in a single unit, are used for some specialized tubing fittings, such as Storz fire hose connectors. A picture of such fittings appears in, below. Interchangeable garden hose fittings made by GEKA are also hermaphroditic, relying on a rubber gasket to make the final connection.
Downspout
s are used to convey rainwater from roof gutters to the ground through hollow pipes or tubes. These tubes usually come in sections, joined by inserting the male end into the female end of the next section. These connections are usually not sealed or caulked, instead relying on gravity to move the rainwater from the male end and into the receiving female connection located directly below.Ductwork
for conveying air in HVAC systems typically uses gendered connections. Typically, the airflow through a ductwork connection is from male to female. However, connections formed opposite to this convention can be seen in some systems, since all connections are typically sealed with duct sealing mastic or tape to prevent leakage anyway. The flow convention is usually loosely adhered to for simplicity of design and to reduce the number of gender changer fittings required, but exceptions are made whenever expedient.Electrical and electronic
Although the gender of tubing and plumbing fittings is usually obvious, this may not be true of electrical connectors because of their more complex and varying constructions. Instead, connector gender is conventionalized and thus can be somewhat obscure to the uninitiated. For example, the female D-subminiature connector body projects outward from the mounting plane of the chassis, and this protrusion could be erroneously construed as male. Instead, the gender is determined by the innermost part, the male pins, rather than by the protrusion of the connector that fits inside the shield of the mating connector.. The distinction is more obvious with ring crimp lug connectors which are placed around a screw post, but again with spade or split ring crimp lug connectors the end alone is not obviously female.Further confusion can be caused by the term jack, which is used for both female and male connectors and typically refers to the fixed side of a connector pair. IEEE STD 100, IEEE-315-1975 and IEEE 200-1975 define plug and jack by location or mobility, rather than gender.
A connector in a fixed location is a jack, and a moveable connector is a plug. The distinction is relative, so a portable radio is considered stationary compared to the cable from the headphones; the radio has a jack, and the headphone cable has a plug. Where the relationship is equal, such as when two flexible cables are connected, each is considered a plug. Jacks use the reference designator prefix of J and plugs use the reference designator prefix of P.
It is common practice to use female connectors for jacks, so the informal gender-based usage often happens to agree with the functional description of the technical standards. However, this is not always the case; often-seen exceptions include a computer's AC Power Inlet and EIA232 DE9 Serial Port, or the male coaxial power jacks for connecting external power adapters to portable equipment.
To summarize, it is considered best practice to use male and female for connector gender, and plug and jack for connector function or mobility.
Variant usages
In the United Kingdom, many Commonwealth countries, and some non-English-speaking countries, such as France, the word jack may refer to the plug on the end of a removable cable. These connectors were originally referred to as jack plugs, or plugs intended to be mated with fixed receptacles, or sockets, but the second word was dropped. This variant usage is in direct contradiction to common usage and official standards in North America.For example, in the UK, the connector on the end of a headphone lead is known as a jack that plugs into a socket on the main unit. The same usage also generally occurs in Italy, where the English word jack is commonly used to indicate the connector on the end of a headphone lead.
Abbreviations and alternate terminology
The letters M and F are commonly used in part numbers to designate connector gender. For example, in Switchcraft XLR microphone or hydrophone connectors, the part numbers are denoted as follows:- A3F = Audio 3-pin female connector;
- A3M = Audio 3-pin male connector.
For example, a female high-density D-subminiature connector with a size 1 shell can be named DE15F or DE15S. Both terms mean the same thing but could be construed to be completely different items. Similarly, a male standard-density D-sub with a size 1 shell can be named DE9M or DE9P; a female standard-density D-sub with a size 2 shell can be named DA15F or DA15S; a male high-density D-sub with a size 3 shell can be named DB44M or DB44P; and so forth.
Gender selection in electronic design
Electronic designers often select female jack connectors for fixed mounting on electronic equipment they design. This is usually done because female connectors are more resistant to damage or contamination, by virtue of their concealed or recessed electrical contacts. A damaged motherboard connector can result in the scrapping of an expensive piece of electronic equipment. The risk of damage is reduced by relegating the more exposed male contacts to connecting cables, which can be repaired or replaced at lower cost.For example, in an RS-232 serial port, the male connector is more mechanically fragile than the female connector. Cost and reliability considerations probably drove the design decision to use female jack connectors on many computer terminals for the serial port, despite being in direct violation of the connector gender convention explicitly specified in the RS-232 standard for DTE connections. This confusing reversal of the RS-232 connector gender convention has caused many hours of frustration for ill-informed end users, as they tried to troubleshoot non-functional serial port equipment connections.