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14
AMPERAGE TABLE/OVERCURRENT
PROTECTION
This table provides the total connected heating element load in
amperes for branch circuit conductor and over current protection
sizing. Single-phase heaters are two wire circuits. Three-phase
heaters are three wire circuits. In addition to the foregoing a
ground conductor may be required.
The rating of the overcurrent protection should be computed on
the basis of 125 percent of the total connected load amperage.
Where the standard ratings and settings do not correspond with
this computation, the next higher standard rating or setting
should be selected.
HEATER CIRCUITS
The water heater’s electrical components are pictured and
identified in Figure 1.
The following describes the heater circuits and includes wiring
diagrams. All heater circuits are designed for 60 hertz alternating
current.
CONTROL CIRCUIT
The heater is equipped with 120 volt control circuit where all of
the heating elements are switched on and off together. This is
the standard circuit and may be used with up to five elements.
The control circuit wiring is 14 AWG rated 600 volts, 105°C.
A low water cutoff switch is available as an optional safety device
to protect the elements from damage due to lack of water in the
heater.
POWER CIRCUIT
Power circuit wiring is rated 600 volts, 75°C.
WIRING DIAGRAMS
The following wiring diagrams are included in this manual to
show typical arrangement of electrical components in the control
and power circuits by voltage and phase characteristics. They
are to be used as a reference by the installer or servicer in
performing their work. An actual diagram of the water heater
wiring is furnished with the heater.
STANDARD KW INPUTS
Standard Immersion Number of Full Load Current In Amperes
KW Heaters*** 50A Contractors Single Phase Three Phase
Ratings No. Of Wattage 208V 240V 480V 208V 240V 277V 480V 208V 240V 480V
3 1 3,000 14.4 12.5 10.8 6.3 8.3 7.2 3.6
6 1 6,000 1 28.8 25.0 21.2 12.5 16.7 14.4 7.2
9 1 9,000 1 43.3 37.5 32.5 18.8 25.0 21.7 10.8
12 1 12,000 1 57.7 50.0 43.3 25.0 33.3 28.9 14.4
15 1 15,000 72.1 62.5 54.2 31.3 41.6 36.1 18.0
18* 1 18,000 86.5 75.0 65.0 37.5 50.0 43.3 21.7
24 2 12,000 2 115.4 100.0 86.6 50.0 66.6 57.7 28.9
30 2 15,000 2 144.2 125.0 108.3 62.5 83.3 72.2 36.1
36* 2 18,000 173.1 150.0 130.0 75.0 99.9 86.6 43.3
45 3 15,000 3 3 216.3 187.5 162.5 93.8 124.9 108.3 54.1
54 3 18,000 2 N/A 225.0 194.9 112.5 149.9 129.9 65.0
60** 4 15,000 4 4 N/A 250.0 216.6 125 166.7 145 72
75** 5 18,000 5 5 3 N/A 312.5 270.8 156 208.4 181 90
90** 5 18,000 N/A 375.0 324.9 188 250 217 108
* 208V models use one additional immersion heater.
** Available on 50 gallon models or larger.
***Each immersion heater contains three electric elements.