Distributed Dimming - Reduced Wiring Cost By Shared Neutrals

Reduced Wiring Cost By Shared Neutrals

Because shared neutrals often cause problems when run upstream of dimmers, the idea of locating the dimmer as far downstream as possible reduces wiring costs by allowing shared neutrals to be run all the way up to and including the dimmer.

The one form of (much copied) distributed dimming is the Rosco 6-dimmer bar that is supplied by a 3-phase 20-Amp circuit, usually connected to an L21-20 receptacle.

As a conservative measure, the 6-dimmer bar usually comes wired with 10-gauge (although 12 gauge would be enough for 20Amps) wire, having a common (shared) neutral, and three hot wires, plus a ground (5 conductors in total, including the ground).

A shared neutral wire, such as "10/4" (10 gauge, 4-conductor, not including ground), runs to an L21-20 receptacle into which the dimming bar is plugged in.

On the dimming bar, there are six duplex receptacles, each one fed from an individually controlled (by way of DMX512) channel. The first and fourth outlet are on the first phase, the second and fifth on the next phase, and so-on, so that the phases are interleaved.

Another devices are made by "Entertainment Technology" (who do a sinewave dimmer version), Botex, Showtec's "multidim", stairville's power-bar and eurolite.