Show power terms

Company switch

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A company switch is a dedicated, fused electrical disconnect installed in a venue for visiting productions to tie into, typically providing 200–400 A of three-phase power via cam-lock connections. It exists so touring rigs can connect heavy loads without touching house panels.

Tie-in

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A tie-in is the act of connecting a production’s feeder cable to a venue’s power source, usually at a company switch. Tie-ins are performed on a dead, locked-out switch by qualified or licensed personnel, connecting ground first, then neutral, then phases.

Spider box

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A spider box (or lunch box) is a portable power distribution unit that breaks a large feeder circuit into multiple smaller circuits, typically taking cam-lock or 50 A input and offering breakered 20 A duplex outlets. The name comes from the many cables radiating from it on a show floor.

Feeder

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Feeder is the heavy-gauge cable (commonly 4/0 or 2/0 with cam-lock ends) that carries a production’s main power from the source (company switch or generator) to distribution. Feeder runs are measured, ramped, and protected because they carry hundreds of amps.

kVA vs kW

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kVA (kilovolt-amperes) is apparent power; kW (kilowatts) is real power actually converted to work. They differ by the power factor: kW = kVA × PF. Generators are rated in kVA, so a 100 kVA generator delivers 80 kW at a 0.8 power factor.

Tails

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Tails are the bare-ended feeder conductors that land directly on the lugs of a company switch or panel under a qualified electrician’s hands. "Tie-in with tails" is the traditional alternative to cam-equipped switches.

Edison

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Edison is crew shorthand for the standard US household plug and outlet (NEMA 5-15/5-20). "Edison ends," "an Edison run," and the quad box full of Edisons are the retail layer of show power.

Twist-lock

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Twist-locks are NEMA locking connectors (L5-20, L6-30, L21-30 and kin) that rotate to latch, used wherever vibration or a snagged cable would defeat a straight-blade plug. The cam-lock chart on this site tables the common types.

GFCI

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A GFCI (ground fault circuit interrupter) trips power in milliseconds when current leaks to ground, protecting people from shock. Outdoor and wet-location show power runs on GFCI protection by code and by sense.

House power

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House power is the venue’s built-in electrical supply (wall outlets and panels) as opposed to production power from company switches or generators. Useful for small loads; famous for being shared with the coffee maker.

Isolated ground

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An isolated ground circuit gives sensitive equipment a ground path separate from the general equipment ground to reduce noise coupling. Audio distros advertise it; correct bonding still governs, per code.

Ampacity

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Ampacity is the current a conductor can carry continuously without exceeding its temperature rating, set by gauge, insulation, and conditions. Breakers protect cable ampacity, which is why breaker size follows wire size.

Neutral

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The neutral is the grounded return conductor of an AC service. In three-phase wye systems it carries the imbalance between legs, which is why balanced loading keeps neutrals (and the crew) happy.

Bus bars

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Bus bars are the rigid conductor bars inside switches, panels, and distros that circuits tap. "Landing on the bus" is electrician-speak for connecting to them; only qualified hands go near an energized bus.

Step-down transformer

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A step-down transformer converts a higher service voltage to a lower one (480 V to 208/120 V being the show classic), letting productions use big-building services. It arrives on wheels, heavy, and hums.

Part of the eventools.io Show Dictionary, a free glossary of live event production terminology.