YORK INTERNATIONAL
52
Electrical Data
ELECTRICAL SERVICE SIZING
In order to use the electrical service required for the cool-
ing only eco
2
rooftop, use the appropriate calculations
listed below from U.L. 1995. Based on the configuration
of the rooftop, the calculations will yield different MCA
(minimum circuit ampacity), and MOP (maximum
overcurrent protection).
Using the following load definitions and calculations,
determine the correct electrical sizing for your unit. All
concurrent load conditions must be considered in the
calculations, and you must use the highest value for
any combination of loads.
Load Definitions:
•
LOAD1
is the current of the largest motor – com-
pressor or fan motor.
•
LOAD2
is the sum of the remaining motor currents
that may run concurrently with LOAD1.
•
LOAD3
is the current of the electric heaters – zero
for cooling only units.
•
LOAD4
is the sum of any remaining currents greater
than or equal to 1.0 amp.
Use the following calculations to determine MCA
and MOP for units supplied with a single-point power
connection:
MCA = (1.25 x LOAD1) + LOAD2 + LOAD3 + LOAD4
MOP = (2.25 x LOAD1) + LOAD2 + LOAD3 + LOAD4
If the MOP does not equal a standard current rating of
an overcurrent protective device, then the marked maxi-
mum rating is to be the next lower standard rating. How-
ever, if the device selected for MOP is less than the
MCA, then select the lowest standard maximum fuse
size greater than or equal to the MCA.
TABLE 24 –
COMPRESSOR DATA
Compressor Nominal Voltage
Model
Quantity
Model
400/3/50
per Unit
RLA
LRA
50
4
SZ160
24.2
135
55
4
SZ160
24.2
135
60
4
SZ185
27.9
175
65
4
SZ185
27.9
175
70
4
SZ125
17.9
120
2
SZ160
24.2
135
75
4
SZ125
17.9
120
2
SZ160
24.2
135
80
6
SZ160
24.2
135
85
6
SZ160
24.2
135
90
2
SZ160
24.2
135
4
SZ185
27.9
175
95
2
SZ160
24.2
135
4
SZ185
27.9
175
