Stage pin connector - AbsoluteAstronomy.com

A stage pin connector is a standard cable type for theatrical lighting in North America.

Uses

Stage pin connectors are generally used for conducting dimmed power from a dimmer

Dimmer

Dimmers are devices used to vary the brightness of a light. By decreasing or increasing the RMS voltage and, hence, the mean power to the lamp, it is possible to vary the intensity of the light output...

to stage lighting

Stage lighting

Modern stage lighting is a flexible tool in the production of theatre, dance, opera and other performance arts. Several different types of stage lighting instruments are used in the pursuit of the various principles or goals of lighting. Stage lighting has grown considerably in recent years...

instruments, although occasionally they can power other equipment.

Construction

The first stage pin connectors had two cylindrical pins, one for line (hot) and one for neutral, arranged symmetrically in a rectangular housing. The housing was milled from a solid block of fiberglass

Fiberglass

Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

or bakelite which may have been impregnated with asbestos

Asbestos

Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...

for fire resistance, with a screw-on cover. Later connectors (including those currently manufactured) use molded plastic housings.

These two-pin connectors were not polarized, and thus the line and neutral conductors could be exchanged depending on which way the connectors were mated. Two-pin connectors may still be found on some equipment and are often saved by electricians for wiring ungrounded fixtures (particularly practicals), though this may not be advisable from a safety standpoint.

Modern stage pin connectors have incorporated a third pin for a safety ground connection and are commonly referred to as two pin and ground (2P&G) to distinguish them from their ungrounded two-pin predecessors. The ground pin is situated between the line and neutral pins and closer to the latter. This asymmetrical configuration effectively polarizes the connector ensuring that the line and neutral conductors are not exchanged in a properly wired installation. The ground pin is also longer than the other two, ensuring that the safety ground connection is made first when making a connection.

All stage pin connectors have longitudinal slits in the male pins that allow for compression when inserted into the female sockets to increase friction and therefore the mechanical security of the connection. A special tool appropriately called a pin splitter may be used to expand this slit and spread the two halves of the pin to compensate for wear. A knife may be used to the same effect, but this technique risks both personal injury and damage to the connector.

For some time Union Connector produced 2P&G connectors with a distinctive yellow cover that featured a locking tab in the ground pin that provided a positive mechanical lock to prevent accidental disengagement of the connectors. This design required special connectors on both the male and female side in order to work, meaning that all connectors in an installation would need to be replaced to see a real benefit to the locking feature. The expense of this proposition as well as the unpopularity of the connector itself among technicians led the locking feature to eventually be dropped, and locking connectors are no longer manufactured. The locking connectors that are still found occasionally in installations or spare parts bins are often referred to as "Union Connectors", though the Union Connector brand now features only standard non-locking stage pin connectors.

Since their introduction, stage pin connectors have been available in 20 A, 30 A, 60 A, and 100 A varieties, with the higher-current connectors being not only far larger in size but also with a different pin configuration for ground, neutral and line. Care must be taken when repairing or building these larger connectors, because ground is on the outside pin and neutral is in the middle, with the far pin still being the line.

Extension cables

Most extension cables made with 20A stage pin connectors use 12/3 type SOOW or SJOOW cable which has three individually insulated 12 awg (American Wire Gauge

American wire gauge

American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire...

) stranded conductors inside a larger jacket. The internal insulation is usually colored black (for line), white (for neutral) and green(for ground). This cable configuration can safely handle the full 20 ampere rating of the connector. The designation SOOW or SJOOW refers to the cable's insulation construction and type

Portable cord

A portable cord, which is also known as portable cordage or flexible cord, is a cable with multiple conductors used for functions requiring flexibility...

. This type of cable is very hard-wearing, resistant to oil and moisture, and resists the kinking that can result in internal conductors unlaying and twisting, which is a common problem with the SJTW cable often used in household-grade extension cords. However, older cable made using natural rubber is susceptible to dry-rotting, particularly in the heat generated by lighting equipment. This can cause the insulation to fail and expose or short circuit

Short circuit

A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....

the conductors leading to shock or fire hazard if old cable is not inspected regularly and replaced as needed.

Multicircuit cable

Some stage pin extension cables may be constructed from cable with six or more conductors. This cable can be fitted with multiple stage-pin connectors at either end enabling the single cable to carry multiple independent output channels of dimmed power. Each channel or circuit should have its own line, ground, and neutral conductor independent of the other circuits, though in some cases the ground or neutral lines may be shared among circuits.

Alternatively, multicircuit cables may terminate in multicircuit (socapex
Socapex
Socapex connectors are 19-pin electrical connectors used in film, television and stage lighting to terminate the ends of a multicable. They are wired with six hot pins, six neutral pins, and six grounded pins, the final pin being a center pin used to help the male end of the connector align...

) connectors which may in turn be mated to panel-mount multicircuit connectors on dimming equipment or distribution boxes, other multicircuit cables (to increase length), or break-in/break-out adapters to convert the multicircuit connection to a set of stage pin connections.

Equipment cabling

The cables integrally connected to lighting instruments (often referred to as pigtails

Patch cable

A patch cable or patch cord is an electrical or optical cable used to connect one electronic or optical device to another for signal routing. Devices of different types are connected with patch cords...

) may use 3-conductor SJOOW or SOOW cable or individual high-temperature wires inside of a fiberglass sleeve. In the either case, the cable is often smaller gauge and sized to the current rating of the equipment it services.

Adapters

Twofer

A twofer is a cabling device used in theatrical stage lighting. It allows two stage lighting instruments to be connected to one dimmer. It is wired in parallel, such that voltage is consistent throughout the circuit, and current is shared between the two instruments. Twofers can be used in...

s are used to connect two devices to a single source. They may be constructed using individual wires inside of a fiberglass sleeve or 12/3 cable, though the latter type tends to be harder to construct and more prone to failure.

In some situations it may be desirable to connect an Edison-equipped device to a stage-pin source, such as when using a household fixture as an on-stage practical. Or it may be desirable to connect a stage pin-equipped device to an Edison source, for testing purposes or applications such as using theatrical equipment for architectural

Architectural lighting design

Architectural lighting design is a field within architecture and architectural engineering that concerns itself primarily with the illumination of buildings. The objective of architectural lighting design is to obtain sufficient light for the purposes of the building, balancing factors of initial...

or retail displays. In either case, adapters may be constructed with a female Edison connector and a male stage pin connector or vice versa.

Some facilities feature 60 or 100 ampere circuits which have larger versions of the stage pin connector to match the higher current rating. Since it is unusual to require more than 20 amperes on a single circuit with modern lighting equipment, adapters may be made to convert a single 60 or 100 ampere stage pin connection to three to five 20 ampere stage pin connections. However, each downstream connection must be independently protected by a fuse or breaker to avoid exceeding the current rating of downstream cables and connectors.

Stage pin versus NEMA 5-15 (Edison) connectors

The primary advantage of the stage pin connector over the NEMA

Néma

Néma is a town in southeastern Mauritania, close to the border with Mali. It is located at around . It is the capital of Hodh Ech Chargui Region and of the Néma Department....

5-15 connector (commonly known as an Edison plug) is its increased durability and resistance to damage due to its more robust construction and the ability to compensate for wear with a pin splitter. Having a distinct connector designated for dimmable power also helps prevent confusion of dimmed and non-dimmed circuits which could lead to equipment damage. Even the smallest stage pin connectors are rated for 20 A, which translates to 2.4 kW at 120 V, compared to the 15 A and 1.8 kW of the NEMA 5-15.

Despite the advantages of stage pin connectors, many smaller installations use Edison connectors due to their availability and the ease of connecting equipment to outlets already available in a building. This reduces refit costs, particularly when small portable dimming packs (often 4×1.2 kW channel models) are used. Such installations may also use inexpensive store-bought extension cables, though care must be taken to ensure that the ratings of such extension cables are not exceeded.

Though the initial cost of constructing a 12/3 stage pin extension cable is higher than simply purchasing an equivalent edison extension cable, the maintenance costs of the former are ultimately lower for several reasons. To begin with, less maintenance will be required as a result of the more rugged construction. When maintenance is required, many cable faults may be repaired by disassembling the connector, replacing broken components with spares acquired by cannibalizing

Cannibalization of machine parts

Cannibalization of machine parts, in maintenance of mechanical or electronic systems with interchangeable parts, refers to the practice of removing parts or subsystems necessary for repair from another similar device, rather than from inventory, usually when resources become limited...

other broken connectors, trimming away defective sections of cable, and reapplying the connector to the cable. This sort of repair is not usually possible with Edison connectors, particularly the factory-molded type. If a connector is beyond repair, a new stage pin connector is often less expensive than a replacement Edison connector when purchased from local vendors.

Safety

Though stage pin connectors are usually used in part to distinguish dimmed circuits from non-dimmed Edison circuits, newer theatrical installations may have several dimmed circuits that terminate in Edison outlets at various locations for convenience; thus care must be taken to avoid using these circuits for non-dimmable equipment. Connecting certain non-dimmable appliances or equipment to dimmed circuits may result in damage to the dimming equipment or the downstream device.

Most modern stage pin connectors feature a ground pin that is longer than the line and neutral pins, ensuring that the ground connection is made first, and thus the safety ground is in place before line voltage is applied to the downstream equipment.

As an added precaution, some SPCs are built with a clear housing on one side. This allows a user to confirm that they are wired correctly before connecting them.

On some older female pin receptacles, the actual electrical contacts are not very deeply recessed in the plug body and can easily be accidentally contacted resulting in an electric shock if the circuit is live. This was one advantage of the Edison outlet in that it was impossible to contact live parts unless something conductive was inserted into the slots. New connectors have addressed this problem by mounting the contacts deeper inside the connector body so they cannot be accidentally contacted.

A major disadvantage to the design of this style of connector is that it is possible to mate the connectors with one reversed such that the ground pin is inserted into the line socket and the line pin is inserted into the ground socket. For equipment mechanically attached to grounded building structures such as a lighting instrument mounted to a batten or grid this will cause a line-ground short circuit. For equipment not attached to a building ground, such as a floor-mounted lighting instrument, this condition will cause the chassis of the equipment to become electrified creating a shock hazard. Care must therefore be taken to avoid misaligning plugs. It is also possible to mate stage pin connectors such that the ground pin is inserted into the neutral socket and the neutral pin is inserted into the ground socket, but this mistake does not usually result in a fault condition unless there is a hot-neutral reverse upstream in the cabling.

Standards

Stage pin connectors are specified by United States Institute for Theatre Technology

United States Institute for Theatre Technology

The United States Institute for Theatre Technology is a membership organization which aims to advance the skills and knowledge of theatre, entertainment and performing arts professionals involved in the areas of design, production and technology, and to generally promote their interests...

standard USITT S3-1997 Standard for Stage Pin Connectors.

Other connectors used in theatre applications

Many theatres also use Edison plugs/connectors, which is the standard connector used in homes and businesses in North America, because of their availability and the ability to connect household fixtures to a theatrical control system. Twist-lock connectors are used in many theatres because of their locking feature, which will not allow fixtures to become accidentally disconnected. It is important to note that all connectors used to power lighting fixtures must be rated at 20 amperes or higher, depending on local electrical codes. Temporary high-power distribution wiring often employs camlock connectors to connect dimming equipment, power distribution unit

Power distribution unit

A power distribution unit is a device fitted with multiple outputs designed to distribute electric power, especially to racks of computers and networking equipment located within a data center....

s, controllers for motorized chain hoists, and other high-power equipment to a company switch, generator, or other tie-in point.

UK theatrical lighting installations normally use the BS 546 type plug rated at 15 A (the higher phase voltage of 230 V allows lower currents for the same power) or occasionally IEC 60309

IEC 60309

IEC 60309 is an international standard from the International Electrotechnical Commission for "plugs, socket-outlets and couplers for industrial purposes". The highest voltage allowed by the standard is DC or AC; the highest current, ; and the highest frequency,...

16 A industrial plugs. Most dimmer racks also use IEC 60309 32 A or 63 A plugs on the non-dimmed side.

External links

http://ww4.usitt.org/bookstore/downloads/U87%20S3-StgPinStandard20050610.pdf

(This is standard defined by the USITT and a source for this article)

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.