I‘m working on this house that has some ground wires on various lines, and then some without ground wires. There is a large white wire going from the panel on the neutral side to the cold water (copper) line. There are neutral and ground wires in both the neutral and ground bar in the panel. I also found lots of other wires in the basement running to the pipes (3 or 4). The problem is the bath fan requires a ground to work. How can I get it to work? Is it a bad idea to rewire the panel so the grounding bar is grounded to a rod outside? Then have all grounds available on the grounding bar, and all neutrals on the neutral bar (removing the wire to the pipe?) What re my options?
Not intended to be snarky here, but from the question it indicates you are over your head and It really would be a good idea to get an electrician to do this electrical work. But the facts are that at the electrical service the neutral and ground are bonded, they don't have to be on the same bar, but certainly can be. Sub panels including panels in detached building have separate grounds and neutrals. Ground rods may not have been required when the house was built, but revisions to the service would require updating to an acceptable grounding electrode, the water pipe does need to be grounded within 10' of entering the building, but requires a supplemental grounding electrode, and a ground rod may be the best way to ground the system. Grounding receptacles to just any water pipe is not acceptable by code, it requires connection at the panel, connection to the wire to the grounding electrode, or connection to a grounding electrode (which could be a metal water pipe, but only if buried for 10' and connected within 10 of entering the building).
HyperDog does not know of what he speaks, so do not take his advice. If you have a metal water pipe, the ground conductor from the neutral bar MUST go to the pipe. Ground rods are generally very poor grounds, and are not nearly as good as footing rebar, metal piping buried in the ground, well casings, etc. But, for new installations, a water pipe ground electrode must be augmented by at least one ground rod; 2 rods if the resistance to earth is more than 25 ohms. You should have a licensed electrician check out your grounding and bonding. There is a big difference between grounding and bonding. Running a separate ground to a receptacle or a fan/light is allowed ONLY on exposed conductor (knob and tube) systems. From what you describe, you have a system that has been piece-mealed and installed by non professional persons. That is dangerous. If you do not understand equipment ground conductors and ground electrode conductors, do not attempt to fix this. PLEASE hire a licensed electrician who does. And ask him (or her) point blank if they know what ground electrode conductors and equipment ground conductors are - if they don't know, don't hire them.
The neutral is required by Code to be bonded to the (buried metallic), cold water service, and any other available ground (Like a driven ground rod which, if added and bonded to the neutral ground buss at the panel increases the over-all safety of the system.).). Technically you should have separate ground and neutral buses, but the two are so close electrically that it shouldn't matter much. Likewise, that that 'large white wire' should be green is not a 'real' issue, and can easily be corrected with a green 'sharpie'.(Just mark it at the terminations.) (You can purchase an additional ground bus and screw it to the panel enclosure if you really want to.) Bonding anything else between the neutral and ground systems elsewhere is a 'No-No'. I am concerned about the bonding of other water pipes.That's supposed to be a continuous metallic system. If non-metallic piping is inserted in the water supply or waste system the bonds should 'jump' the non metallic section.
