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Decoder System Design

Wire Specifications & Rules

Wire, and wire installation, is a key factor in successful decoder installations. Substitution of wire and wire splices is at the installer’s own risk and is the major cause of start-up service troubles.

Hunter provides various wire models for use with ACC decoder systems. Hunter recommends the color-coded wire selections with outer jacket for additional protection of decoder wire.

Wire Specifications
Model Description Specifications
ID1GRY Gray outer jacket

14AWG/2.08 mm2 solid-core twisted pair, 2500 ft / 760 m per standard spool

 

(Use up to 10,000 ft / 3 km)

ID1PUR Purple outer jacket
ID1YLW Yellow outer jacket
ID1ORG Orange outer jacket
ID1BLU Blue outer jacket
ID1TAN Tan outer jacket
ID2GRY Gray outer jacket

12AWG/3.3 mm2 solid-core twisted pair, 2500 ft / 760 m per standard spool

 

(Use up to 15,000 ft / 4.5 km)

ID2PUR Purple outer jacket
ID2YLW Yellow outer jacket
ID2ORG Orange outer jacket
ID2BLU Blue outer jacket
ID2TAN Tan outer jacket

The DUAL Difference

DUAL systems operate up to 48 decoders. DUAL uses the same wire, but the distances are not quite as great:

  • 14 AWG/2.08 mm2 = 5,000 ft/1,500 m, max
  • 12 AWG/3.3 mm2 = 7,500 ft/2,300 m, max
  • DUAL provides 3 two-wire paths to the field

ID1TAN, Showing Twisted Pair

The twisted pairs are not shielded or armored, but the outer jacket provides protection from abrasion and sunlight damage. Conduit is not necessary unless local regulations require it (the two-wire path is low voltage). Shielding, steel armor, and conduit will not inhibit performance and are permissible when desired.

  • Paths: Each two-wire output run of wire is called a "path". The ACC99D provides up to 6 path outputs to the field, and the decoders may be installed on any or all of them in any combination. Color-coded external jackets allow each path to be identified in the field.
  • It is not necessary to connect the paths to one another. Each path runs from the controller to the last decoder in the path, and simply stops there. Generally, looping a two-wire path from one output to another (back to the controller) is not recommended. It provides little benefit and complicates troubleshooting.
  • Never connect a wire path from one controller to the wire paths from another controller

Hunter requires twisted wire meeting the above specification on all paths. The twist in the wire is an essential part of the surge suppression scheme and works very well. The twist in the wire minimizes the difference in potential during a surge, and adds inductance. Since lightning damage is never covered by warranty, it is in the installer’s best interest to share what Hunter has learned in nearly two decades of decoder installations, by using twisted wire that meets all the above specifications.

Color coding is mandatory. The red/blue coding is a convenience for matching the wires to Hunter decoders. External colorcoded jackets aids in diagnostics after initial installation and protects wires from shorts to earth.

Using pre-existing wire: This is strongly discouraged by Hunter for the following reasons:

  • It is unlikely that the pre-existing wire meets the specifications for gauge, twist, and solid copper
  • Pre-existing wire will not be color-coded correctly for the decoder wires
  • Pre-existing wire may have invisible problems (shorts, breaks, increased resistance, or damaged insulation) that will be inherited by the new installation

It is unwise to take chances on large projects by trying to "beat" wire specifications.

 

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