The bonding conductor used for bonding metal parts or dead metal of signs and outline lighting systems together and to the branch circuit equipment grounding conductor shall not be smaller than...

• A. 12 AWG copper
• B. 14 AWG copper
• C. 16 AWG copper
• D. 18 AWG copper

Answer: (B)

Bonding conductors provide a low-impedance path so that any fault current can reach the equipment grounding conductor and bring the fault to a quick stop, while also keeping metal parts at the same electrical potential. For signs and outline lighting, the bonding conductor that ties metal parts to the circuit’s equipment grounding conductor must be sized according to the circuit’s overcurrent protection, as shown in the NEC table that links the conductor size to the OCP rating.

For typical sign or outline lighting circuits (15 A or 20 A), the minimum copper bonding conductor size is 14 AWG. This ensures the path is large enough to carry any fault current until the overcurrent device trips. Sizes smaller than 14 AWG would be undersized and not compliant, while larger sizes are acceptable but not required by the minimum rule.