I am hooking up a 100 amp subpanel with a 2/2/2 overhead wire. Is the overhead bare wire a neutral or a ground? Should I take the connector bar out that is pre-installed in the subpanel between the neutral and ground bars? Should I bond the panel with the bonding screw? (I am backfeeding the sub to a 100amp brkr so I have a service disconnect.

Are you located in the U.S.A.

If you are, then you need to understand some basic information.

To begin with, Neutral and Ground serve two distinct missions.

Neutral is the return path from the source to the circuit terminus.

How far is the distance between the source (main panelboard?) and the location of the secondary panelboard?

A secondary panel feeder, must be 4 wire. 2 (hots), Neutral, Ground.

There are mast heights and locations that need to be reviewed by you. I'm pretty sure that you will be required to get a permit.

At the secondary location, the panelboard can be either a MCB or a MLO panelboard.

If I were doing the work, I would set an Emergency Cut Off switch in front of a MLO panelboard.

At the secondary panelboard, Neutral and Ground must be isolated from each other. That means that you must use a separate Grounding System.

Neutral and Ground conductors cannot be put on the same bus
Bar. Neutral and Ground cannot be bonded to each other anywhere else but at the Main Panel board.

Just curious but did you do a load calculation at the new location to make sure you actually need 100 Amps?

Yes, here is a little more info, thanks. It is USA, This panel is actually the second subpanel. The first one is a 125 amp 4 wire underground fed subpanel. I am adding a second subpanel fed from the first. Coming out of the first I have a disconnect breaker (100 amp), I have 2/2/2 going up the mast to the arial wire which is a 2/2/2 arial wire connected with split bolt splices rubber and taped. The overhead wire is only three wire as described two sheathed and 1 bare. When I get to second mast split bolt to three sheathed #2 wires running down the mast to the second panel. Both leads feed another brkr. For disconnect. The third wire is connected to the neutral bar. At this time the neutral and the ground are connected by a copper rod. I don't know if the panel is bonded by the bonding screw. There is a number 4 bare to a ground rod attached to the ground bar. My issue is that we are noticing some surging from the equipment operation. I checked at the first panel and have 246v, and each leg is showing about 114v. At the second although I have 248 volt reading both legs together. When I measure each one I get 148 volt on one leg and 97 volt on the other. There in lies my problem. What and why do you think that is? Thank you for your time and consideration on this. It is appreciated.

The bare neutral conductor has a loose connection and needs to be repaired immediately. Or can be anywhere in the neutral circuit.

Shut power off to the sub panel as the abnormal voltages can damage equipment, and at times has caused fires.

I do not have time with the details of your installation right now, someone will get back you.

Get the wiring repaired ASAP.