the system is a 10 SEER Carrier heat pump about 12 years old. The problem
is that the outside unit trips breakers about 5 or 6 times each summer.
This occurs on very hot days when the electric demand is very high. It
never occurs in spring, fall or winter.The unit is powered by a 30amp
circuit. The spec on the unit requires something like 28 amps on startup.
The cable that powers this unit and the line set are both extremely long,
probably over 80'. This is a condo unit and the line set and wiring are
not accessible in any reasonably easy fashion. It would take significant
demo in other peoples units to access the wire. Here is what I have done
to work around this problem: tightened the wires in the panel, the
disconnect and the unit, changed the 15' of wire from the disconnect to
the unit to a higher guage (8 ga), put on a hard start kit, changed the
breaker, changed the entire panel from an old Federal Pacific to a new
Square D. I imagine that the delivery of electricity during these peak
demand moments is insufficient to power on the unit and it trips the
breaker during startup. Of course, it is impossible to ever catch the unit
in this mode.