BCXC-SVX01A-EN
21
Electrical
Requirements
Installation
Table I-ER-2. Available Electric Heat Kw (min.-max)
Unit Size
Voltage
12
18
24
36
54
72
90
115/60/1
1-3
1-3
1-3
1-3
1-3
1-3
1- 3
208/60/1
1-4
1-6
1-8
1-8
1-8
1- 8
1-8
230/60/1
1-4
1-6
1-8
1-8
1-8
1-8
1-8
277/60/1
1-4
1-6
1-8
1-11
1-11
1-11
1-11
208/60/3
1-4
1-6
1-8
1-11
1-12
1-12
1-12
230/60/3
1-4
1-6
1-8
1-11
1-12
1-12
1-12
460/60/3
1.5-4
1.5-5
1-8
1-11
1-16
1-21
1-30
575/60/3
2-4
2-4
1-8
1-11
1-16
1-21
1-30
220/50/1
1-4
1-6
1-8
1-8
1-8
1-8
1-8
240/50/1
1-4
1-6
1-8
1-8
1-8
1-8
1-8
380/50/3
1-4
1-5
1-8
1-11
1-16
1-20
1-28
415/50/3
1.5-4
1.5-5
1-8
1-11
1-16
1-21
1-30
190/50/3
na
na
na
na
na
na
na
Notes:
1. Heaters are available in the following Kw increments : 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0,
4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0,
19.0, 20.0, 21.0, 22.0, 24.0, 26.0, 28.0, 30.0.
2. Magnetic contactors are standard. Mercury contactors are available on horizontal
units only.
3. Units with electric heat are available with or without door interlocking disconnect
switch.
4. Units with electric heat are available with or without line fuses.
5. Units with electric heat must not be run below the minimum cfm listed in the
general data section.
6. Electric heat is balanced staging: 1 stage = 100%, 2 stages = 50%/50%
7. Electric heat is not available on 190/50/3 units.
Minimum Circuit Ampacity (MCA) and
Maximum Fuse Size (MFS) Calculations
for Units with Electric Heat
Use these formulas to calculate the MCA
and MFS.
Heater amps = (heater kW x 1000)/
heater voltage
Note: Use 120V heater voltage for 115V
units. Use 240V heater voltage for 230V
units. Use 480V heater voltage for 460V
units. Use 600V heater voltage for 575V
units.
MCA = 1.25 x (heater amps + all motor
FLA’s)
MFS or HACR type circuit breaker =
(2.25 x largest motor FLA) + second
motor FLA
+ heater amps (if applicable)
HACR (Heating, Air-Conditioning and
Refrigeration) type circuit breakers are
required in the branch circuit wiring for all
units with electric heat.
See Table I-ER-2 for electric heat kW and
Table I-ER-3 on page 22 for motor FLAs.
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
Useful Formulas
kW = (cfm x
∆
T)/3145
∆
T = (kW x 1000)/voltage
Single phase amps = (kW x 1000)/voltage
Three phase amps = (kW x 1000)/
(voltage x 1.73)
Electric heat MBh = (Heater kW) (3.413)
