Why Would My Common Wire be Carrying 120Volts When Hooked Directly To Ground Bus In box? Only Two Rooms In The House Affected.

Can you describe how you measured this? What kind of meter did you use?
How many wires are in the hallway light? What colors are they? Did you measure the voltage on these also?

There are some possibilities how this could happen but it would be unusual...

I Measured It With A Fluke Meter. There Are Two Wires, One White And One black. I Measured Both And They Are Reading 122.3 Volts Each.

Good morning, Notsohandywoman,

Depending on what you are testing and how you are testing it, there is nothing wrong with your reading.

Remember, you are dealing with an Electrical "Circuit". What goes out, comes back. The Black (Ungrounded conductor) is the supply conductor. The White (Neutral or Return) is the "Grounded" conductor.

If you connect a meter probe to your "Black" conductor and then the Red meter probe to the White, you will see 120 (+/-) on the meter.

If you connect the black probe to the Neutral Bus or the Ground bus or even the metal can that your panelboard is mounted to and then test the black conductor you will get 120 volts(+/-). This is normal.

With the black probe on any grounded surface or conductor you should see 0 Volts when testing either the White or Ground conductor of a surface. Again, this is normal.

Now, if you are testing a White conductor to Ground and you see 120 Volts, then there is a problem. This all by itself tells you that there is a "open" situation between the Neutral on this circuit and the grounding system.

We really need more information about what you are testing and why. What is the failure you are trying to correct.

Just for the record, The only place that "Neutral" and Ground are allowed to be connected together is at the main service panel.

I do not know what level of electrical experience you have, so please ask more questions and give us some more information on the failure and what you are testing for.

hallway light carrying 120 volts
How many switches control this hallway light and where are you testing. If you have two or more switches and are testing at a switch, the white wire is not a neutral (common) but is a traveler (a hot carrying current to the other switch).