Trane FADA, Installation & Operation Manual, Page: 38 / 84

38 FAXA-SVX01B-EN
Installation
electrical
requirements
rating equal to the MOP value. If the MOP
value does not equal a standard device
size as listed in NEC 240-6, select the
next lower standard device rating. If the
next lower standard rating is less than
125% of the current rating of the electric
heater load, select the next higher
standard device rating. If the selected
MOP is less than the MCA, then reselect
the lowest standard device size which is
equal to or larger than the MCA, pro-
vided the reselected device size does not
exceed 800 amps.
The MOP value selected should be the
largest of the three sets of MOP value
calculations.
Disconnect Switch Sizing (DSS) – if field
provided and installed
If the unit is ordered with a factory-
installed non-fused disconnect switch,
this sizing equation is not necessary. If
the disconnect is to be field-provided and
installed, use the following equation to
determine its rating:
DSS = 1.15 x (load 1 + load 2 + load 3 +
load 4)
Select the DSS that is the largest of the
three sets of DSS calculations. Select a
disconnect switch size equal to or greater
than the DSS value calculated.
Set #4: Units with Electric Heat, Dual
Source Power
Dual source power is required only on
some 208V and 230V units when
provided with electric heat. Those units
are:
size voltage elec ht kW
031 208V or 230V 42 kW or
larger
040 208V or 230V 42 kW or
larger
051 208V or 230V 70 kW or
larger
066 208V or 230V 70 kW or
larger
Dual Source Power
For units with dual source power, use
two different sets or MCA and MOP
calculations, one for each power
connection. MCA1 and MOP1 represent
the values calculated for the operation of
the compressors and condenser fans.
For the calculations of MCA1 and MOP1,
use the instructions from set #1
previously in this section.
MCA2 and MOP2 represent the values
calculated for the operation of the unit in
heating mode:
MCA2 = (1.25 x load 3) if heater kW is
less than 50kW
or
(1.0 x load 3) if heater kW is 50kW or
greater, MOP2 = (1.25 x load 3)
Select an overcurrent protective device
rating for the heating circuit equal to the
MOP2 value. If the MOP2 value does not
equal a standard device size as listed in
NEC 240-6, select the next lower stan-
dard device rating. If the selected MOP2
is less than the MCA2, then reselect the
lowest standard device size that is equal
to or larger than the MCA2, provided the
reselected device size does not exceed
800 amps.
Disconnect Switch Sizing (DSS) – if field
provided and installed:
If the unit is ordered with a factory-
installed non-fused disconnect switch, this
sizing equation is not necessary. If the
disconnect is to be field-provided and
installed, use the following equation to
determine its rating:
DSS2 = 1.15 x (load 3)
Select the DSS2 value that is the largest
of the three sets of DSS2 calculations.
Select a disconnect switch size equal to or
greater than the DSS2 value calculated.
Load Definitions
Load 1:
• supply fan • exhaust fan
• reheat comp (A) • condenser fan 1 (A)
• main comp 1 (B) • condenser fan 2 (B)
• main comp 2 (C) • condenser fan 3 (C)
• main comp 3 (D) [5100/6600]
• total energy wheel
Load 3:
• electric heat
kW < 50
kW > 50
Load 4
• control power transformer (loads > 1
amp [1T1 - 208/230])
• gas heat
• factory-wired convenience outlet
the compressors and condenser fans. For