This building has no other grounding electrode system. This facility has documented 4 direct lightning hits with no internal damage to the building or technology systems. Our experience at this facility and 140 other locations around the USA indicates deeper electrodes are more effective in dissipating lightning while maintaining low resistance. I know that there are a lot of opinions that says lightning will not conduct deep into the earth due to frequency and impedance issues, however the results indicate the opposite. I'm afraid I can't get overly excited by all the efforts to develop low resistance grounds.
Lightning is a short duration, double-exponential pulse, having a very fast rise time.
Consequently, horrendous transient voltages are developed, despite low values of measured resistance. Although the interior would never experience the direct effects of a strike, enough energy would be conducted inside to cause problems with sensitive assets. 12 Lightning recently struck a large oak tree 20ft. from the corner of my home. It discharged into one of the roots of the tree, which obliviously was in contact with my buried phone cable and TV cable. The lightning entered the home thru the phone line and cable line.