Actually scorpio's post is not as accurate as Stubbie's.
First off, if you think #6 is "anaconda sized" you should come work with us for a a few days. :whistling2: And we are not talking about a "gazillion" rods. We are talking about two or three.
The antenna's rod is known as a supplementary rod. It requires a #6 because that is what the code tells us it needs. A rod can only carry so much fault current so the wire connected to it is useless over a certain size. #6 in this case.
The reason it must be #6 is NOT because the antenna needs #6. The #6 is a bonding jumper between rods. It has NOTHING to do with the antenna itself.
For a reference:
Blue text is the NEC Handbook Commentary
810.21 Grounding Conductors — Receiving Stations
Grounding conductors shall comply with 810.21(A) through 810.21(K).
(A) Material The grounding conductor shall be of copper, aluminum, copper-clad steel, bronze, or similar corrosion-resistant material. Aluminum or copper-clad aluminum grounding conductors shall not be used where in direct contact with masonry or the earth or where subject to corrosive conditions. Where used outside, aluminum or copper-clad aluminum shall not be installed within 450 mm (18 in.) of the earth.
(B) Insulation Insulation on grounding conductors shall not be required.
(C) Supports The grounding conductors shall be securely fastened in place and shall be permitted to be directly attached to the surface wired over without the use of insulating supports.
Exception: Where proper support cannot be provided, the size of the grounding conductors shall be increased proportionately.
(D) Mechanical Protection The grounding conductor shall be protected where exposed to physical damage, or the size of the grounding conductors shall be increased proportionately to compensate for the lack of protection. Where the grounding conductor is run in a metal raceway, both ends of the raceway shall be bonded to the grounding conductor or to the same terminal or electrode to which the grounding conductor is connected.
(E) Run in Straight Line The grounding conductor for an antenna mast or antenna discharge unit shall be run in as straight a line as practicable from the mast or discharge unit to the grounding electrode.
(F) Electrode The grounding conductor shall be connected as follows:
(1) To the nearest accessible location on the following:
a. The building or structure grounding electrode system as covered in 250.50
b. The grounded interior metal water piping systems, within 1.52 m (5 ft) from its point of entrance to the building, as covered in 250.52
c. The power service accessible means external to the building, as covered in 250.94
d. The metallic power service raceway
e. The service equipment enclosure, or
f. The grounding electrode conductor or the grounding electrode conductor metal enclosures; or
(2) If the building or structure served has no grounding means, as described in 810.21(F)(1), to any one of the individual electrodes described in 250.52; or
(3) If the building or structure served has no grounding means, as described in 810.21(F)(1) or (F)(2), to an effectively grounded metal structure or to any of the individual electrodes described in 250.52
(G) Inside or Outside Building The grounding conductor shall be permitted to be run either inside or outside the building.
(H) Size The grounding conductor shall not be smaller than 10 AWG copper, 8 AWG aluminum, or 17 AWG copper-clad steel or bronze.
(I) Common Ground A single grounding conductor shall be permitted for both protective and operating purposes.
(J) Bonding of Electrodes A bonding jumper not smaller than 6 AWG copper or equivalent shall be connected between the radio and television equipment grounding electrode and the power grounding electrode system at the building or structure served where separate electrodes are used.
The requirements for grounding are in accordance with Article 250. Antenna masts must be grounded to the same grounding electrode used for the building's electrical system, to ensure that all exposed, non–current-carrying metal parts are at the same potential. In many cases, masts are connected incorrectly to conveniently located vent pipes, metal gutters, or downspouts. Such a connection could create potential differences between lead-in conductors and various metal parts located in or on buildings, resulting in possible shock and fire hazards. An underground gas piping system is not permitted to be used as a grounding electrode.
Section 810.21(J) clarifies that the bonding requirement applies only to electrodes at the same building or structure. The use of separate radio/television grounding electrodes is not required.