Installation - Electrical
UNT-SVX07E-EN
81
MCA and MOP Calculations
Minimum circuit ampacity (MCA) and Maximum
Overcurrent Protection (MOP) calculations for units with
single-phase electric heat:
Heater amps = (heater kW x 1000)/heater voltage
Note:
Use 120 V heater voltage for 115 V units. Use 240 V
heater voltage for 230 V units.
MCA = 1.25 x (heater amps + all motor FLAs)
MOP = (2.25 x largest motor FLA) + second motor FLA +
heater amps (if applicable)
Select a standard fuse size or HACR type circuit breaker
equal to the MCA. Use the next larger standard size if the
MCA does not equal a standard size.
Standard fuse sizes are: 15, 20, 25, 30, 35, 40, 45, 50, 60
amps
Fan-coil electric heat MBh = (heater kW) (3.413)
Table 33. Electric heat kW, low vertical fan-coil
Unit Size Unit Voltage
kW
kW
kW
kW
3.0
115
1.00
1.50
2.00
4.0
115
1.00
1.50
2.00
2.50
6.0
115
1.00
1.50
2.00
2.50
Note:
Low vertical units are only available with electric heat in combination
with the two-row cooling coil.
Table 34. Force-Flo single-stage, max kW electric heat
Unit
Size
Voltage
# Wires Heater kW
Heater amps/
ph
02
208/60/1
2
2.25
10.90
240/60/1
2
3.00
12.50
277/60/1
2
3.00
10.90
208/60/3
3
2.25
6.30
240/60/3
3
3.00
7.30
480/60/3
4
3.00
3.70
03
208/60/1
2
4.50
21.70
240/60/1
2
6.00
25.00
277/60/1
2
6.00
21.70
208/60/3
3
4.50
12.60
240/60/3
3
6.00
14.50
480/60/3
4
6.00
7.30
04
208/60/1
2
5.70
27.50
240/60/1
2
7.50
31.30
277/60/1
2
7.50
27.10
208/60/3
3
5.70
15.90
240/60/3
3
7.50
18.10
480/60/3
4
7.50
9.10
06
208/60/1
2
7.90
38.00
240/60/1
2
10.50
43.80
277/60/1
2
10.50
38.00
208/60/3
3
7.90
21.90
240/60/3
3
10.50
25.30
480/60/3
4
10.50
12.70
Note:
All data based on individual units. Electric heat will operate only with
fan at high speed.
Table 35. Force-Flo single stage, low kW electric heat
Unit
Size
Voltage
#
Wires kW
amps
/ph
kW
amps
/ph
kW
amps
/ph
02
208/60/1
2
0.8
3.7
1.5
7.3
240/60/1
2
1.0
4.2
2.0
8.4
277/60/1
2
1.0
3.7
2.0
7.3
03
208/60/1
2
2.3
10.9
240/60/1
2
3.0
12.5
277/60/1
2
3.0
10.9
208/60/3
3
2.3
6.3
240/60/3
3
3.0
7.3
480/60/3
4
3.0
3.7
04
208/60/1
2
2.3
10.9
240/60/1
2
3.0
12.5
277/60/1
2
3.0
10.9
208/60/3
3
2.3
6.3
240/60/3
3
3.0
7.3
480/60/3
4
3.0
3.7
06
208/60/1
2
2.3
10.9
3.3
15.9
240/60/1
2
3.0
12.5
4.5
18.8
277/60/1
2
3.0
10.9
4.5
16.3
208/60/3
3
2.3
6.3
3.3
9.2
240/60/3
3
3.0
7.3
4.5
10.9
480/60/3
4
3.0
3.7
4.5
5.5
08
208/60/1
2
2.3
10.9
3.3
15.9
4.5
21.7
240/60/1
2
3.0
12.5
4.5
18.8
6.0
25.0
277/60/1
2
3.0
10.9
4.5
16.3
6.0
21.7
208/60/3
3
2.3
6.3
3.3
9.2
4.5
12.5
240/60/3
3
3.0
7.3
4.5
10.9
6.0
14.5
480/60/3
4
3.0
3.7
4.5
5.5
6.0
7.3
10
208/60/1
2
2.3
10.9
3.3
15.9
5.7
27.5
240/60/1
2
3.0
12.5
4.5
18.8
7.5
31.3
277/60/1
2
3.0
10.9
4.5
16.3
7.5
27.1
208/60/3
3
2.3
6.3
3.3
9.2
5.7
15.9
240/60/3
3
3.0
7.3
4.5
10.9
7.5
18.1
480/60/3
4
3.0
3.7
4.5
5.5
7.5
9.1
12
208/60/1
2
2.3
10.9
3.3
15.9
6.6
31.8
240/60/1
2
3.0
12.5
4.5
18.8
9.0
37.5
277/60/1
2
3.0
10.9
4.5
16.3
9.0
32.5
208/60/3
3
2.3
6.3
3.3
9.2
6.6
18.4
240/60/3
3
3.0
7.3
4.5
10.9
9.0
21.7
480/60/3
4
3.0
3.7
4.5
5.5
9.0
10.9
Note:
All data based on individual units.
