Subpanel to Detached shop Panel

[Starplex]

I have done extensive searches, but have yet to find an exact answer to my question. So I purchased a home this year that was built and wired (all copper) in 2000 and included a detached shop. It has a 200amp service to the main breaker. (Note:the house uses mostly natural gas, thus electric load is minimum). Out of the main breaker box they wired a subpanel into the garage (100 amp breaker). The subpanel was wired using 1/0 (3 wire w/o ground, obviously not in compliance with 2008 code, but okay for 2000?). Out of this subpanel they pulled feed to the detached shop, using two #2 AWG hot conductors (underground pvc) and one #4 AWG neutral conductor (no 4th wire ground). These conductors come up on the outside of the shop to a small breaker box (4 spaces) and have a single 100 amp breaker. It then leaves this box with two #2 AWG hot conductors and one #2 AWG neutral conductor to a 40 space panel inside the shop. In both the shop and garage panels the grounds and neutrals are co-mingled on the neutral bus, thus bonded.
I am installing a small central A/C unit in the detached shop and have the following questions: 1). should the neutrals & grounds be seperated in the panel in the detached shop? Since there is no 4th ground wire, should the grounding bus go to a grounding rod at the detached shop? Currently there is no grounding rod, but I can install one. If not bonded, and grounds seperated the grounds will just terminate at the box. Or do I leave as is.
2). For the subpanel in the garage, I cannot pull a 4th wire (two story house), thus should I leave this panel as bonded, as is or separate grounds and neutrals? Sorry for the long post.

 

[charlie b]

I am closing this thread, in accordance with the Forum?s rules. This Forum is for professional electricians, inspectors, engineers, and other members of the electrical industry. We are not permitted to provide ?how-to? assistance to a person who is not employed in this industry.