Addendum 04 - Radio Towers.docx

This is an Addendum 04 document issued by the Missouri Department of Transportation (MoDOT) addressing supplier questions regarding radio tower grounding system specifications for a state contract opportunity. The addendum responds to a supplier's request for clarification on grounding system design requirements, specifically addressing concerns that the R56 specification alone provides insufficient information for proper grounding system design and installation.

MoDOT's response clarifies that Motorola R56 grounding specifications establish industry standards for telecommunications sites and require the creation of a single, low-resistance common grounding system with a target resistance of under 5 ohms. The response specifies minimum requirements including bare copper conductors of at least #6 AWG, ground rods of 8 feet or longer with a minimum diameter of 5/8 inches, ground plates with a minimum area of 2 square feet, and ground rod spacing of 10 to 15 feet. All elements including power, communications, and lightning protection systems must be bonded together with appropriate bonding jumpers and clear pathways for surge dissipation. These specifications exceed basic electrical code requirements to ensure critical system safety at telecommunications sites.