Requirements to the installation of ground electrodes on overhead line supports up to 1000 V are described in the Electric Installation Code. However, despite this, designers often have questions about the necessity of designing grounding on supports and points of placing ground electrode systems.
Here are the answers based on the EIC:. According to section 1.7.102 repeated grounding is perform at the ends of the overhead line and its branches:
At the ends of the overhead lines or branches more than 200 m long, as well as at the inputs to the HV lines to the electrical installations, where automatical cut off power is used as protection against indirect contact, repeated grounding of the PEN-conductor should be carried out. Therefore,natural ground electrodes should be used first of all, for example, underground parts of the support and grounding devices for lightning surges.
Grounding resistance for supports of overhead power line is regulated in paragraph 2.4.38 .:
Grounding devices designed for repeated grounding, surge protection, grounding of electrical equipment installed on the overhead line supports should be carried out at the supports of the overhead lines. Grounding device resistance should be not more than 30 ohms.
Design and install properly! All the necessary regulations on grounding and lightning protection, see here.