A twofer is a cabling device used in
theatrical
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors to present experiences of a real or imagined event before a live audience in a specific place, often a stage. The performers may communic ...
stage lighting
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts. . It allows two
stage lighting instrument
Stage lighting instruments (lanterns, or luminaires in Europe) are used in stage lighting to illuminate theatrical productions, concerts, and other performances taking place in live performance venues. They are also used to light television st ...
s to be connected to one
circuit. It is wired in
parallel
Parallel may refer to:
Mathematics
* Parallel (geometry), two lines in the Euclidean plane which never intersect
* Parallel (operator), mathematical operation named after the composition of electrical resistance in parallel circuits
Science a ...
, such that
voltage
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...
is unchanged in the twofer, and
current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (hydr ...
is split and divided over two connectors. Twofers are used in conjunction with cables with the same types of connectors.
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The name is a corruption of the phrase "Two For One".
UK terminology
The UK equivalent of the twofer is a Grelco. The name derives from the manufacturer of the original examples, but is now generally adopted for all examples regardless of manufacturer. It typically relates to a splitter for the UK 15 A power connections commonly used for stage lighting. It is usually an integral block rather than a plug with two cables leading to two sockets. Where a single plug goes to three or more sockets it is sometimes known as a Trelco.[http://www.shepperd.co.uk/glossary/pages/Lighting/Cables_and_Distro/ ]
Typically for most other power connector types used in theatre, the term ''(2-way) splitter'' is used.
Australian terminology
For several decades, much rock-and-roll and other lighting used "Par Cans", each containing a 120-volt PAR 64 lamp. As the mains supply is 240 volts these must be connected in series, via an adapter lead or box featuring two sockets.
Notes
Stage lighting
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