MARRS HO Module Standards: Revision History

Revision 2.01, 17 October 2009 (current)

• Minimal acceptable gauge for mainline wiring is decreased from 12 gauge to 14 gauge. Members had experienced difficulty in locating electrical components suited for use with the heavier wire.

Revision 2.00, 14 October 2007

• Complete rearrangement and write-through.
• The MARRS HO standards now directly incorporate the appropriate NMRA Standards and Recommended Practices by reference. MARRS-specific features are described as exceptions to the NMRA documents.
• Anderson PowerPole connectors are adopted for inter-module wiring, with standards modeled after NTrak's DCC wiring recommendations.

Standards for HO Scale Modular Layout, revised through 09 January 1998

• Original version of the MARRS HO standard.
• Loosely derived from the NMRA standard, with inter-module wiring based on 1/4" phono jacks and plugs instead of Cinch-Jones connectors.
• As the "revised through" date indicates, this standard was a codification of existing practices. MARRS began exhibiting HO modules in April 1996, built to essentially this standard.