Trane IntelliPak 1 with Symbio 800 Installation, Operation And Maintenance Manual page 53

To arrive at the correct MCA and MOP values for these
units, two sets of calculations must be performed. First
calculate the MCA and MOP values as if the unit was in
cooling mode (use the equations given in Set 1). Then
calculate the MCA and MOP values as if the unit were in
heating mode as follows. (Keep in mind when determining
LOADS that the compressors don't run while the unit is in
heating mode).
For units using heaters less than 50 kW:
MCA = 1.25 x (LOAD1 + LOAD2 + LOAD4) + (1.25 x
LOAD3)
For units using heaters equal to or greater than 50 kW:
MCA = 1.25 x (LOAD1 + LOAD2 + LOAD4) + LOAD3
The nameplate MCA value will be the larger of the cooling
mode MCA value or the heating mode MCA value
calculated above.
MOP = (2.25 x LOAD1) + LOAD2 + LOAD3 + LOAD4
The selection MOP value will be the larger of the cooling
mode MOP value or the heating mode MOP value
calculated above.
Select a fuse rating equal to the MOP value. If the MOP
value does not equal a standard fuse size as listed in NEC
240-6, select the next lower standard fuse rating.
RT-SVX072D-EN
Note: If selected MOP is less than the MCA, then select the
lowest standard maximum fuse size which is equal
to or larger than the MCA, provided the selected
fuse size does not exceed 800 amps.
Dual Source Power units (200–230V with Electric Heat)
These units will have two circuit values shown on the
nameplate. The first circuit value will be the refrigeration
(cooling mode) values calculated per Set 1. The second set
of circuit values shown on the nameplate will be for the
electric heating circuit as follows.
MCA = (1.25 x LOAD3)
MOP = (1.25 x LOAD3)
Select a fuse rating for the electric heating circuit that is
equal to the MOP value obtained in the equation above. If
the MOP value does not equal a standard fuse size as
listed in NEC 240-6, select the next lower standard fuse
rating (see note below for exception).
Note: If the available MOP option is less than the MCA
obtained in the equation above, then reselect the
lowest standard maximum fuse size which is equal
to, or larger, than the MCA, provided the reselected
fuse size does not exceed 800 amps.
Installation
53