neutral bus, groud bus

Wondering about in the breaker panel..
there are neutral busses and ground busses..

Aren't these bonded together? Wondering why the two,
what the difference is, and how critical it is to wire the
ground to the ground one and the white to the neutral one
seein' they are connected together any way.

Thanks

The neutral and ground bus are connected at the Main Panel only.

If you install a panel as an auxiliary, you need to keep the neutral and ground separate and carry them back to the main panel that way.

Along these same lines...how much of a "no-no" is it to have a circuit getting power from the main panel, but having it's neutral and ground come back to the sub-panel? The neutral/ground bar in my main panel is full, so I had to move 2 neutrals and 2 grounds to the sub panel neutral bar. The sub panel ground bar is connected correctly to the main panel neutral/ground bar.

Seems like it'd be OK, but if not I'll get it changed ASAP. There's just no friggin room in that main panel bar!

Hi:

RE: "The neutral and ground bus are connected at the Main Panel only.
If you install a panel as an auxiliary, you need to keep the neutral and ground separate and carry them back to the main panel that way."

Yes, it's my main panel. I wired it up a few months ago but then have been
reading about the two different busses. An electrician installed the panel
and wired one ciruit so I'd have temporary electric and lights in the building
while I did other work. He had the bare copper and white wire on the same
bus. One under the next crew down from the other. I wired the rest of the circuits accrodingly. Then I was reading different things about they are seperate busses and started worring.

In certain manufacturer's panels, there is a dedicated grounding block. It won't be attached to the main neutral buss, it will just be screwed to the back of the panel. Your panel has to be bonded to use this type of grounding block. By Bonded, the factory supplied green bonding screw must be installed through the neutral buss into the back of the panel. Neutral and ground wires provide very different and distinct services. Neutral provides for continuity of electrical circuits. Ground wires provide protection, safety to the user of the circuit. They are not interchangeable, Neutral wires are insulated for a reason, anywhere that there is a live circuit and the neutral wire is disconnected, the circuit is broken. (The only exception being double or triple pole circuits. But even now most residential double pole circuits require a neural for timers, clocks or transformers for electronic equipment.) The neutral wire coming from a potential load back to the panel is just as dangerous and carries just as much load as the hot wire. An uninsulated ground wire is NOT suited for this purpose.

Ground, neutral and hot need to stay together, beginning and ending in the same place. You could seriously overload the neutral in a subpanel or it's feeder wires, by running too many neutrals into it. Neutrals are not fuse protected and the wire could see extreme heat before the breakers ever trip.

When it comes to electricity, using the go ahead anyway plan when you don't know what you're doing, can land you with a burned home or a fast trip to dead. Always ask, never assume anything will be alright when you just don't know.