How frequently should cable run in metallic tubing be bonded to the tube?

Bonding cable runs in metallic tubing is essential for ensuring safety and system integrity when it comes to lightning protection and grounding systems. The correct approach requires that the cable be bonded at both ends of the metallic tube. This is necessary to maintain a continuous conductive path that can effectively handle fault currents and ensure that any potential differences between the cable and the metallic tube are minimized.

When the cable is bonded at both ends, it allows for an equalization of electrical potential, reducing the risk of arcing or short circuits. Additionally, it ensures that the metallic tubing itself is effectively grounded, which is critical for both safety and functionality. Proper bonding at both ends also facilitates maintenance, because should an inspection or service be needed, the safety of the system will be maintained throughout the entire length of the tubing.

Other choices suggest less frequent bonding, such as only at one location or at specific intervals. This would not provide the comprehensive grounding effect needed for the protection of the electrical system and surrounding environment, thus leaving the system vulnerable to issues that bonding at both ends would prevent.