Why should metal parts be kept free of paint or coatings at electrical bonding points?

Why should metal parts be kept free of paint or coatings at electrical bonding points?

• A. Paint coatings improve conductivity at bonding points.
• B. Bonding quality is unaffected by presence of paint.
• C. Any coating is acceptable at electrical bonding points.
• D. Removing paint at bonding points ensures low impedance and reliable bonding.

Answer: (D)

At bonding points you need a low-impedance, reliable electrical connection. Paint or coatings sit on the metal surface and act as insulators, preventing metal-to-metal contact and increasing contact resistance. They can also trap moisture and encourage corrosion underneath, weakening the bond over time. Removing paint ensures bare metal surfaces contact cleanly, allowing the fastener to grip properly and the connection to meet required torque, keeping the impedance low. So, take off the paint at bonding points to ensure a solid, dependable bond.

At bonding points you need a low-impedance, reliable electrical connection. Paint or coatings sit on the metal surface and act as insulators, preventing metal-to-metal contact and increasing contact resistance. They can also trap moisture and encourage corrosion underneath, weakening the bond over time. Removing paint ensures bare metal surfaces contact cleanly, allowing the fastener to grip properly and the connection to meet required torque, keeping the impedance low. So, take off the paint at bonding points to ensure a solid, dependable bond.