I am working on a project that presently has an existing 800A, 120/240V, single-phase service and an 800A, 240V, three-phase service. The new owner would like to install a new 277/480V service and eventually upgrade the existing floors to electric heat and upgrade the HVAC. Can I leave the existing 240V services and install a new 277/480V service? I would have to get the utility company's permission and run by the AHJ, but I feel based upon 230.2(D) I should be allowed to do this. I would also install a shunt trip button at the existing entrance of the 240V services that would trip the new main at the 480V equipment.
Thanks.
Thanks.