Stage pin connector

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A newer stage pin connector. Note the GR denoting the longer ground pin, which is not quite in the center to prevent the plug being inserted upside down

An older style male Stage Pin Connector

A stage pin connctor (generally known as SPC) is a standard cable type for theatrical lighting in North America.

1 Construction
2 Safety
3 Wiring
4 Uses
5 Standards
6 Other Connectors Used in Theatre Applications
7 See also
8 External links

[edit] Construction

Like most lighting cables, a spc has 3 conductors: Hot (usually black), Ground (green), and neutral (white). The pins are in a line, with the ground pin in the middle, and the neutral pin closer to it than the 'hot' pin. The cable used is generally very low gauge because of the large amounts of current present. Usually screw terminals hold crimp connectors onto the base of each pin. Each pin actually consists of two semi-cylinders which have a gap between them. This allows them to apply pressure to a socket and maintain better contact.

[edit] Safety

The main reason for using stage pin connectors is to avoid connecting appliances and other household devices that can cause equipment damage or fire if ran on a dimmer. It also prevents the use of common household 15 amp extension cables, which is against electrical code in most states.

Another built-in safety feature is that the ground pin is longer than the other two. This means that even if the lighting instrument has a severe electrical fault, such as the live conductor shorting to the fixure's body, as long as the safety ground is working, a technician is protected. 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.

[edit] Wiring

Some Stage lighting instruments for which polarity does not matter use two white cables, one for hot and one for neutral. In this case, it does not matter which is which, but it is imperitive that green remain ground. On other occasions, a colored cable with a black stripe will be used for the hot lead, and a colored cable with a white stripe will be neutral.

[edit] Uses

SPC's are generally used for stage lighting instruments, although occasionally they can power something else. They are usually rated for 15 to 20 amps at 110-120 volts.

Adapters can also be made from edison connectors and SPCs that allow common household lamps to be used with stage pin sockets and dimmers.

Note: It is advisable to not use fluorescent bulbs on dimmers unless it is possible to program the dimmer in a way that will provide voltage properly to the fixture.

[edit] Standards

SPC's are specifies by USITT standard "USITT S3-1997 Standard for Stage Pin Connectors."

[edit] Other Connectors Used in Theatre Applications

Many theatres also use Edison plugs/connectors, which is the standard connector used in homes and bussnesses 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 amps or higher, depending on local electrical codes.