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U.S. Postal Service STD-4C Specification Highlights

Standard 4C Mailbox Specification Highlights

Effective October 5, 2006, all new designs approved for NEW CONSTRUCTION AND MAJOR RENOVATION require U.S. Postal Service STD-4C compliant mailbox systems. The new USPS 4C Standard includes the following specifications:

  • A new compartment form factor minimize size requirement of 12” w x 15” d x 3” h.
  • Eliminates the vertical form factor (5”w × 6”d × 15”h) design.
  • Introduces a parcel locker requirement based on a 1:10 parcel locker to customer compartment ratio.
  • Strengthens security requirements for the entire receptacle.
  • Standardizes and improves tenant compartment lock design.
  • Adds testing requirements to verify acceptability for either indoor or outdoor use. USPS Approved
  • Introduces quality management systems provisions. 
  • Enhances design flexibility for concept, ergonomics, and materials. 
  • Meets Americans with Disabilities Act (ADA) standards.

Florence versatile 4C mailbox suites are designed to meet or exceed the USPS specifications outlined above and in the *Federal Register/Vol. 69, No. 171/September 3, 2004/Rules and Regulations POSTAL SERVICE, 39 CFR Part 111, Standards Governing the Design of Wall-Mounted Centralized Mail Receptacles.

IMPORTANT NOTE TO ARCHITECTS, SPECIFIERS, DESIGN LAYOUT PROFESSIONALS AND INSTALLERS -- Installation/Layout Instructions Specified in USPS Standard 4C – pages 53821-53832* of the above referenced USPS 4C Standard “Notes” sections specify:

4C Mailbox SpecificationsAll 4C Units shall be designed such that they are in compliance with the following installation requirements:

  1. At least one customer compartment shall be positioned less than 48 inches from the finished floor.
  2. No parcel locker compartment (interior bottom shelf) shall be positioned less than 15 inches from the finished floor.
  3. No patron (tenant) lock shall be located more than 67 inches above the finished floor.
  4. No customer compartment (interior bottom shelf) shall be positioned less than 28 inches from the finished floor.
  5. The USPS Arrow lock shall be located between 36 and 48 inches above the finished floor.

ADA Compliance -- the USPS 4C Standard includes a requirement to meet Americans with Disabilities Act** (ADA) standards. (See pg. 53809*)  The Americans with Disabilities Act section that covers clear space and reach dimensions is noted below for reference:

ADA Standards for Accessible Design,  ACCESSIBILITY GUIDELINES FOR BUILDINGS AND FACILITIES Appendix A to Part 36 – Standard for Accessible Design Section 4.2 Space Allowance and Reach Ranges

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