What size copper bonding jumper must be connected between the communications grounding electrode and power grounding electrode system?

The correct size copper bonding jumper between the communications grounding electrode and the power grounding electrode system is 6 AWG. This requirement is established to ensure a low-resistance connection that can effectively carry any fault current and maintain proper grounding.

Using a 6 AWG copper bonding jumper ensures that the size is adequate to handle the potential maximum fault current and provides a path for surge currents, which can be especially important in a fire alarm system. Proper bonding helps in preventing voltage differences between systems, thus reducing the risk of equipment damage and ensuring safe operation during normal and emergency conditions.

The National Electrical Code (NEC) outlines specific guidelines regarding grounding and bonding conductors, emphasizing that proper sizing is critical to safety and functionality. A 6 AWG size effectively meets these code requirements and is suitable for most applications in commercial and industrial settings, thereby providing a reliable grounding connection that contributes to the overall safety of the electrical and electronic systems involved.