Installing Cutler Hammer Surge Protector

I bought a Cutler Hammer CHSPULTRA whole house surge protection device, which comes with 4 wires: two go to a 2-pole breaker, one that goes to the neutral bus bar and the fourth wire that is meant to go to the ground bus bar. My load center does not have a separate ground bus bar. Any idea if both wires can be wired to the neutral bus bar or do I need to have a separate ground bar installed? Cutler Hammer's website was no help. Thanks in advance for any suggestions.

If this is the main service panel, then yes they can, but make sure they go under seperate lugs.

Thanks for the reply. It was the main service panel so I did as you suggested. Surge protector is up and running.

SInce the neutral and ground eventually wind up in the same place, using both would be a "belt and suspenders" approach to it.

Given through those are where any surge will end up, I still think two are better than one.