A 60A 3-phase branch circuit has 60A available on each leg. So you have 60A available on each leg for your loads. Here is a breakdown of your situation of the delta connected single phase loads.
So in summary, when each single phase 208V load is drawing 34.64A, the 3-phase line current will be 60A.
However, since these units should be considered to be a continuous load (3 hours or longer), then a 60A branch circuit should only be loaded to 80% of 60A. This takes you down even further, to 0.8x 34.68 = 28A.
To complete this discussion consider the following scenario as well (not what you have). If you had three Wye connected single phase loads, then they could each draw 60A while the 3-phase line current remained at 60A. However, the voltage across your Wye connected loads would only be 120V. The power would be the same (root3 x 60 x 208 ) or (3 x 60 x 120) for this 60A branch circuit.
Last edited by Homer; December 17th, 2007 at 10:06 PM.
Depending on your skills, doing your own electrical work may risk the health and safety of the community. Always find out how to do things safely before beginning.