NEC 250.24 (B) says a must be used to connect the enclosure, the equipment ground and the grounded conductor at the service disconnect. NEC 250.28 says a main bonding jumper shall be a wire, a buss, a screw or other suitable conductor. So if I use a main 200 amp main breaker panel as my service disconnect and use the green screw to bond the panel to the grounded conductor at the panel neutral bar, and I decide to add another ground bar for equipment grounds to keep my equipment grounding conductors separate from my neutrals for a good looking panel, do I have to run a #4 wire between my added ground bar and the neutral bar or is the enclosure a suitable conductor?