This is another one of those posts about electrical issues that defies logic.
I guess when one thinks about it, many electrical defects defy logic.
Without going into great detail about the differences between electrical “bonding” and electrical “grounding,” just take my word for it that all metal electrical components are supposed to be “bonded” (connected) to the electrical “grounding” system.
For example, consider that big metal box that is the Main Electrical Panel where your Main Service Disconnect and most likely all your circuit breakers are located. This metal box has to be “bonded.” You might wonder, “Well, if it has to be bonded, why doesn’t it come that way from the factory?” This is a reasonable question—and difficult to answer in ten words or less. Just suffice it to say that the panels come from the factory so that they can be used in either “bonded” or “un-bonded” installations. In simple terms, the “Main Service Panel” (where your main disconnect is) always has to be bonded with the grounds and neutrals of the service. When the same panel is used as a “Remote Distribution Panel” (Sub-panel) it would still be bonded—but the neutrals and grounds would no longer be connected together. Confused? Most untrained people that work on electrical equipment are confused too, and this is the reason why it is a defect so often.
This is post is about the bonding of a main panel that I suspect is less than satisfactory. In newer panels there is a “Green” screw that comes on a little piece of cardboard that is supposed to be installed or not installed as the installation calls for. The installer of this panel knew enough to install the screw. He perhaps got lucky—or could read the tag—-but he left the piece of cardboard on the screw.
While there may be some incidental contact with the sides of the screw, I am sure that this is not what the manufacturer intended. The cardboard is preventing full contact of the screw head against the metal part that is supposed to be connected to the metal box via the screw.
A pretty simple fix—and better safe than sorry.
Charles Buell, Seattle Home Inspector
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