ROHN Tower Grounding

Understanding which Grounding Kits to use for what application can be a challenge. Again, REV. F and REV. G play a role in delineating the major differences between the kits and parts supplied with the Complete Tower Packages you purchase. As the approach to Grounding differs between the two, let's first understand which REV.# your Tower may be...

REV. F - All Self-Supporting Towers, all Bracketed Towers and those Guyed Tower Kits with a Part number containing a D between the windspeed and height designations ( ie. R-45G110D040) in the nominclature are REV. F classification and therefore will have these characteristics in common...

REV. F Tower Base Grounding - each Base Grounding Kit will come with material to bond one tower section rail to ground via a clamp, ten foot of solid copper wire and an eight foot ground rod. Depending on the Tower height and Base style, the Tower Kit may contain one, two or three of these Base Grounding Kits. For example; a ten foot Self-Supporting Tower Kit will come with one Base Rail Grounding Kit, the rest will come with two. A Bracketed Tower Kit likewise will come with the same number of Kits depending on Height. A Guyed Tower Kit will come with three of these Kits. A Tower with a Tapered Base Section will come with a Grounding Kit designed to attach via a Lug to one of the side panel plates on the section; rather than a Rail Clamp connection.

REV. F Tower Guy Grounding - each Tower Down Guy Grounding Kit will come with material to bond three Tower Down Guy Anchor locations via a Split Bolt clamp to each Down Guy Stranded Wire with 15 feet of Solid Copper wire to pass through all Split Bolt Bonds on its way to connect with one 8 foot Ground Rod.

REV. G - All Guyed Tower Kits with a a part number containing an R between the windspeed and height designations (ie. R-45G130R040) in the nomenclature are REV. G classification and will have these characteristics in common. The Base and Anchor Grounding Kits model number will end with a "GX"...

REV. G Tower Base Grounding - each Base Grounding Kit will come with material to bond one tower section rail to ground via a clamp, ten foot of solid copper wire and a ten foot ground rod. All Guyed Tower Kits will come with three of these Base Grounding Kits. Those Tower Kits with Tapered Bases will come with hardware to connect to that Base accordingly.

REV. G Tower Guy Grounding - each Tower Down Guy Grounding Kit will come with material to bond three Tower Down Guy Anchor locations via attachment to the Down Guy Anchor Rod itself with a Clamp, 15 feet of Braided Steel Wire Rope to a ten foot Ground Rod.

REV G GROUNDING REQUIREMENT FOR STRUCTURES

Rev G made signicant changes regarding the grounding requirements for structures. A prescriptive approach to grounding was used in Rev F where providing specic grounding leads and ground rods were considered adequate to protect a structure.

Rev G adopted a performance specication approach that requires providing a grounding system that will result in a maximum 10 ohm resistance to earth. Rev G also requires minimum ground lead and ground rod sizes that are greater than the Rev F prescriptive requirements.

Another change is that Rev G does not require specic grounding materials. Rev F required the use of galvanized ground rods with tinned copper leads. Rev G only requires that the leads and connections be compatible with the ground rods from a corrosion standpoint (i.e. minimize di-erence between metals connected).

Rev G does provide default grounding arrangements for various types of structures that are intended to meet the 10 ohm requirement for a wide variety of soil conditions. In accordance with Rev G, the actual resistance of a default grounding system must be veried based on site conditions. Additional ground rods or special grounding systems may be required.

It should be noted that the TIA-222 grounding requirements are meant to protect the structure and foundation from high fault currents. Other grounding requirements are often needed for the protection of antennas, radio equipment and other appurtenances.