What is the minimum size bonding conductor required for bonding metal parts associated with the high-voltage secondary circuit for a neon sign or outline lighting system?

• A. 12 AWG copper
• B. 14 AWG copper
• C. 10 AWG copper
• D. 16 AWG copper

Answer: (B)

Bonding metal parts of the high-voltage secondary circuit is about giving fault current a low-impedance path to ground so any exposed metal parts won’t reach a dangerous voltage if insulation fails. The size of the bonding conductor is set by how much fault current the circuit could deliver before the protective device trips. For neon signs and outline lighting, the typical branch circuit is protected at 15 A, so the minimum bonding conductor size is 14 AWG copper (Table 250.122). A smaller conductor wouldn’t reliably carry the fault current quickly enough to clear the fault, increasing shock risk, while larger sizes are permitted but not required.