Saturday, February 21, 2009

Wiring Standards Part 5: Staging Switch Wiring

Staging uses Atlas code 80 switch machines, which have 3 output wires (red, green, black) of a very small gauge (28? possibly smaller?). The very small gauge is fine given that the machine is designed to accept only a short burst of current when the switch is thrown, and otherwise have no current running.

The wires that come attached to the switch machine are about 12" in length, so require extensions since the distance from switch-to-control panel is at least 3' and usually longer. For the wire extension I am using a "Rainbow" cable from Radio Shack, which is a ribbon of 4 solid 24 gauge wires in colors white, red, black and green. Connections from the ribbon to the switch machine wires are via clear 22-26 gauge butt connectors, also from Radio Shack, with the white wire left in place unused. The butt connectors are reasonably cheap ($2 for a pack of 24, which covers 8 switches) but the rainbow wire is $8 for a 20' roll, so I've got my eye out for alternatives.

Wires are labeled as other wires, with a labeling scheme of number-location, such as "4M" = 4th switch on the Middle tier. Numbering is generally sequential but that is not guaranteed. The wire number is currently the same as the switch number that will be used in operations schematics, but I reserve the possibility of changing the switch number for operations improvements without changing the wire number. Current locations are L (Lower tier), M, and U (Upper tier). The number-alpha format is designed so that switch machine wire labels don't get confused with the alpha-number format of track wires. However such confusion is unlikely anyway given that rainbow strips of wire are visibly very different than the red-and-black twisted pairs for track wire.

Switch wires are run under the subroadbed and bundled together with plastic cable ties to keep them tidy and reduce the possibility of pulling a switch wire out by mistake while reaching for something else.

Switch wires are run to the temporary control panel made up of Atlas switch controls. When the permanent switch control solution is designed some of this wiring may need revision, but at this point I think all that will be required is to disconnect the wires from the Atlas switch controls and connect them to the permanent device.

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