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.
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.
Last edited by Homer : December 17th, 2007 at 06:06 PM.