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LEGEND AND NOTES FOR TABLE 2
LEGEND
*Heater capacity (kW) is based on heater voltage of 208, 240, 480, and 575-V. If power
distribution voltage varies from rated heater voltage, heater kW will vary accordingly.
†Used to determine minimum disconnect per NEC.
NOTES:
1. In compliance with NEC requirements for multimotor and combination load equip-
ment (refer to NEC Articles 430 and 440), the overcurrent protective device for the
unit shall be fuse or HACR breaker.
2. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply voltage is greater than
2%.
Use the following formula to determine the percent of voltage imbalance.
% Voltage Imbalance
Example: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
Determine maximum deviation from average voltage.
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine percent of voltage imbalance.
This amount of phase imbalance is satisfactory as it is below the maximum allow-
able 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your
local electric utility company immediately.
3. Non-fused disconnect switch cannot be used when rooftop unit electrical ratings
exceed 80 amps.
Table 3 — Electric Heater Usage
NOTES:
1. The rated heater voltage is 240, 480, and 575 v. If power distribution voltage varies from rated heater voltage, heater kW vary accordingly.
2. To determine heater kW at voltages other than those shown in table, use the following formula:
Heater kW new = Heater kW rated x (unit power distribution voltage / rated heater voltage)
2
As an example:
For a 16 kW heater rated at 240 v with a power distribution voltage of 215 v
kW new = 16 kW (215/240)
2
kW new = 12.8 kW (rating at 215 v)
FLA — Full Load Amps
HACR— Heating, Air Conditioning and Refrigeration
IFM — Indoor (Evaporator) Fan Motor
LRA — Locked Rotor Amps
MCA — Minimum Circuit Amps
MOCP— Maximum Overcurrent Protection
NEC — National Electrical Code
OFM — Outdoor (Condenser) Fan Motor
RLA — Rated Load Amps
= 100 x
max voltage deviation from average voltage
average voltage
Average Voltage =
452 + 464 + 455
3
=
1371
3
=
457
% Voltage Imbalance = 100 x
7
457
= 1.53%
UNIT
551B
VOLTAGE
(60 Hz)
ACCESORY
kW
ACCESSORY HEATER
PART NUMBER
CRHEATER---A00
ACCESSORY SINGLE POINT BOX
PART NUMBER
CRSINGLE---A00
090
208/230/240
(3 phase)
7.8/ 9.6/10.4 017 006
12.0/14.7/16.0 010 006
18.6/22.8/24.8 011 007
24.0/29.4/32.0 012 007
31.8/39.0/42.4 012+017 009
460/480
(3 phase)
12.8/13.9 016 006
15.2/16.5 013 006
25.6/27.8 014 006
30.4/33.0 015 006
38.4/41.7 014+016 008
575
(3 phase)
17.0 018 006
34.0 019 006
102
208/230/240
(3 phase)
7.8/ 9.6/10.4 017 011
12.0/14.7/16.0 010 011
18.6/22.8/24.8 011 012
24.0/29.4/32.0 012 012
31.8/39.0/42.4 012+017 015
460/480
(3 phase)
12.8/13.9 016 011
15.2/16.5 013 011
25.6/27.8 014 011
30.4/33.0 015 011
38.4/41.7 014+016 014
575
(3 phase)
17.0 018 011
34.0 019 011
120
208/230/240
(3 phase)
7.8/ 9.6/10.4 017 011
12.0/14.7/16.0 010 012
24.0/29.4/32.0 012 012
31.8/38.9/42.4 012+017 015
37.5/46.0/50.0 010+012 015
460/480
(3 phase)
12.8/13.9 016 011
15.2/16.5 013 011
30.4/33.0 015 011
38.4/41.7 014+016 014
46.0/50.0 013+015 014
575
(3 phase)
17.0 018 011
34.0 019 011
51.0 018+019 014
150
208/230/240
(3 phase)
7.8/ 9.6/10.4 017 012
12.0/14.7/16.0 010 012
24.0/29.4/32.0 012 012
31.8/38.9/42.4 012+017 015
37.5/46.0/50.0 010+012 015
460/480
(3 phase)
12.8/13.9 016 011
15.2/16.5 013 011
30.4/33.0 015 011
38.4/41.7 014+016 014
46.0/50.0 013+015 014
575
(3 phase)
17.0 018 011
34.0 019 014
51.0 018+019 014