I had the cover plate off my electric panel because I was adding a branch circuit wire for more outlets in my workshop. But I noticed that three bare copper ground wires were connected to the same bar as the white neutral wires. All the other copper ground wires in the panel were twisted together and connected to a different bar in the panel. Is it okay for those ground wires to be there or are they serving a different propose than the other ground wires?

You have definitely picked up on a common mistake in electrical distribution panels. Often this is an error made by homeowners doing some weekend wiring. The uninsulated copper ground wires in the circuit branch wiring should never be connected to the neutral bus bar in a panel. For instance, the neutral (usually white) wire carries electricity that was not used by the appliance back to the panel. So this wire is actively transporting electricity in the branch circuit.

The circuit ground wires should be idle and should be used to carry current only in emergencies. When you connect these ground wires to the neutral bus bar, the ground wire is more likely to carry everyday household electricity instead of emergency power from situations like short circuits. So, its’ ability to handle these emergencies is diminished. As well, since the ground wire is a bare wire people don’t expect it to be carrying electricity. So there is a potential for shock. The bare copper ground wires in branch circuits are connected to outlet boxes and equipment cases. If these ground wires are bonded with the neutral wires at the panel, the outlet boxes and equipment cases can become energized, which can also lead to shocks.

The simple solution is to shut off the main power to the building and then remove the ground wires from the neutral bus bar. Relocate them on the panel ground terminal where they belong. Whenever these types of problems are detected in a panel, it is a good idea to get a qualified electrician involved in the repairs. Often when you see ground wires that are located on the neutral bus bar, other problems also exist.  So while the electrician is present, ask the person to look for other potential wiring problems like over-sized breakers, circuit wires crossing over the main bus bars, double taps and bonding issues.