Antenna Grounding Buss

Nick,

NFPA 780 lists both aluminum and copper as valid materials to be used in the manufacture of lightning protection components. Aluminum is a little less conductive per square inch than copper, but this is resolved by properly sizing the products. For example, the points or lightning rods are required to be 1/2" diameter in aluminum and only 3/8" diameter for copper. The cable conductor is similarly designed differently with a # 2 AWG copper cable being the minimum size required, while a # 1/0 AWG aluminum must be provided. A completely aluminum system may be considered to be just as effective as the completely copper system, with the exception that aluminum cannot be used in poured concrete nor for any component underground. If the above ground system is all aluminum, then a listed bimetallic fitting is inserted at a transition point above grade with copper system components used for the grounding. There are several instances where one or the other may be preferred, but this generally relates to the item the components will be mounted on. Water running off copper will damage or oxidize aluminum over time, so if you have aluminum guttering, flashings, copings or vents on a roof area - you would want to use an aluminum system. The opposite is also true - if you have a copper roof or copper flashings, you would not want to use aluminum as your lightning product choice. If the materials are to be concealed (not subject to weathering), and there are no incompatibility problems where the point extends through the roof, then either material method could be used. Generally speaking, aluminum is a more cost-effective choice for installations where either material could be acceptable.

Galvanic corrosion occurs when dissimilar metals are in contact and exposed to humidity in an atmosphere of ionized salt content. The further apart the two metals are on the electromotive-series chart, the greater the reaction. The effect of the reaction is to reduce the contact area and, consequently, connection integrity. Most corrosion problems occur with aluminum, which should only be put in contact with aluminum, solder-dipped copper, tin-plated brass and copper or tin-plated aluminum with no undercoat. Also to be avoided is silver- or gold-plated copper in contact with solder-dipped copper.

Creep is another factor that can affect contact integrity. It is defined as a dimensional change with time of a material underload. Certain materials will continue to deform as long as a pressure is applied, such as the loosening of aluminum wire. Special crimps and materials must be used to control this effect. However, aluminum wire is never recommended for grounding purposes.

Larry

Hello Nick,

    In would run a solid copper wire to a groung rod outside of your shack,it is not recomended to attach anything to your electric

service in the house.I would use #2 solid or stranded copper wire,then aluminum solid wire if you had NO CHOICE-alum is cheep and the resistance is minamul the length your running.GL

                          Paul

Nick one thing i did do at my qth was to ground at 4 corners of the radio shack,i placed in 8 foot copper rods at each corner.i am lucky enough to have steel beam flooring so that simplified whole house grounding.then use power company heavy clamps to attach to,effectively grounds shield coax and any pipe masts i may use,14 years and heavy lighting prone area and zero strikes thus far,stay away from aluminum and place those ground rods deep,3 foot inadequate for our ground applications.N7YP/JACK

Thought i might add to put a ground rod deep where it belongs is simple,no hole digging,wet a spot,hand drive starter hole with rod or metal pipe,remove rod fill hole with water and start driving downward,plunge deep as possible then restart same procedure.water in,rod in till it gets hard to gain depth.i have done this for years and never broke a sweat,try it and save backbreaking work.N7YP