hooking 3wire 240v to a split main panel (sub)?

[thcrefugee]

Quick question.
Im putting in a 30a 2-pole breaker and #10-2 wiring to a future light controller.
I understand 240v uses two hots, and a "ground".
My house is a split-unit, and has two meters split from the main service supply lines, each meter feeds its own "sub main panel".

Im looking to put the bare ground wire somewhere in the panel and, I only have a neutral bus bar. The box appears to be grounded to a single wire clamp, but has no bus bar for more grounds.
The neutral bar has 2 bare copper ""grounds""? going to it, but none of the circuits in the house have bare grounds. All branch circuits are black and white wire only. There is no visible ground and neutral connection in my panel.

DO i hook the copper wire from my 240v line to the neutral bar, or slip it in with the ground screw?

Thanks for the help!

 

[thcrefugee]

To help anyone searching in the future.. hello from the past.

I figured out my answer.

After my meter, my panel (although split for a duplex) is the first method of disconnect, so it is considered a main service panel. At this panel, there should be a neutral and ground bond (connection). At any subsequent, Subpanels, there neutral and ground should be isolated. The neutral and ground Should be Bonded, but Only at the main disconnect (main breaker, in main panel).
When hooking my new 240v breaker and outlet up, I could not find a ground bar (for a sub), nor could i find a bonding strap between the ground and neutrals (for a main), Hence why I asked my question.

I will just install a necessary connection between them, and install my 240v 3wire ground wire to the neutral bus that is now bonded with ground.