Table of Contents
Advertisement
Table 25. Maximum wiring distances for low voltage
controls (ft)
Device
Wire Size
Fan speed control
14–22 AWG
Zone sensor
16–22 AWG
Recommendation: Do not bundle or run interconnection
wiring in parallel with or in the same conduit with any high-
voltage wires (110 V or greater). Exposure of
interconnection wiring to high voltage wiring, inductive
loads, or RF transmitters may cause radio frequency
interference (RFI). In addition, improper separation may
cause electrical noise problems. Therefore, use shielded
wire (Belden 83559/83562 or equivalent) in applications
that require a high degree of noise immunity. Connect the
shield to the chassis ground and tape at the other end.
Note: Do not connect any sensor or input circuit to an
external ground connection.
MCA and MOP Calculations
Non-Electric Heat Units
Minimum Circuit Ampacity (MCA) and Maximum
Overcurrent Protection (MOP) calculations for non-electric
heat units
MCA = 1.25 x motor FLAs
MOP = 2.25 x motor FLA
Electric Heat Units
MCA and MOP calculations for electric heat units
Table 26. Available motor horsepower
Unit Voltage
Motor
115/1
208/1
230/1
277/1
60 Hz
208/3
230/3
460/3
575/3
220/1
240/1
50 Hz
380/3
415/3
BCX-SVX002A-EN
Range
500
200
0.5
1.00
1.5
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Heater amps = (heater kW x 1000) / heater voltage
Notes:
•
Use 120V heater voltage for 115V units.
•
Use 240V heater voltage for 230V units.
•
Use 208V heater voltage for 208V units.
•
Use 277V heater voltage for 277V units.
•
Use 480V heater voltage for 460V units.
•
Use 600V heater voltage for 575V units.
MCA = 1.25 x (heater amps + all motor FLAs)
MOP = (2.25 x motor FLA) + heater amps
HACR (Heating, Air-Conditioning, and Refrigeration) type
circuit breakers are required in the branch circuit wiring for
all units with electric heat.
Select a standard fuse size equal to the calculated MOP.
Use the next smaller size if the calculated MOP does not
equal a standard size.
Standard fuse sizes: 15, 20, 25, 30, 35, 40, 45, 50,
60 amps
Useful Formulas
kW = (cfm x DT) / 3145
DT = (kW x 3145) / air flow
Single phase amps = (kW x 1000) / voltage
Electric heat MBh = (Heater kW) (3.413)
Three-phase amps = (kW x 1000)/(voltage x 1.73)
Motor Horsepower
2.3
3
X
X
X
X
X
X
X
X
X
X
X
X
Installation — Electrical
3.5
5
X
X
X
X
X
X
X
X
X
X
X
X
X
83
Hide quick links:
Advertisement
Table of Contents
Troubleshooting
