5.6.5 Parts of the protective grounding system shall be reliably secured in accordance with 5.4.1.2 and provided with good metal-to-metal contact. All connections shall be secured against accidental loosening and shall ensure a thoroughly good connection. The resistance between the protective conductive terminal of 5.6.6 and the accessible non-current carrying conductive parts outlined in 5.6.2 shall not exceed 0.1 Ω.5.6.5.1 When connecting conductive parts to be bonded, paint or coatings in areas of contact shall be removed or paint piercing lock washers shall be used with securement bolts or screws to provide good metal to metal contact. Thread-locking sealants, epoxies, glues, or other similar compounds, and solder alone shall not be used as a securement means as these are not considered reliable. In addition, rivets, hinges (unless metal-to-metal piano type hinges), and parts that may be removed as a result of servicing shall not be relied upon as connections for ensuring continuity of the protective grounding and bonding system.5.6.5.2 Methods of securement considered reliable and ensuring good metal-to-metal contact can consist of the following methods:a) Terminal blocks;b) Pressure connectors, grounding lugs and similar grounding and bonding equipment connectors;c) Exothermic welding processes;d) Machine screw-type fasteners that engage not less than two threads or are secured with a nut; ande) Thread-forming machine screws that engage not less than two threads in the enclosure.