A bonding wire is often mistaken for a ground wire, it does not go to ground but back to the electric panel. When it is connected to black iron *(steel)* piping the paint under the clamp must be removed with a rasp or sandpaper to make a good contact, paint reduces the contact rendering the wire inefficient. If there is a CSST flexible gas line it is mandatory in our area to have it bonded. If the bonding wire is aluminum an anti oxidant paste should be smeared on the wire before inserting it under the screw connector.
