Each internal power circuit is fused for safety.
Each power circuit to an immersion element is
fused at a maximum of 48 amps. Power circuits
may be fused at lower current levels as needed to
balance current on three phase units. The power
circuit fuses are held by a spring loaded fuse
block rated for the voltage specified to operate
the water heater.
The control circuit is also fused on both the
primary and secondary sides of the control circuit
transformer.
The power to the immersion electric heating
elements is switched by a definite purpose
magnetic contactor. The contactor is supplied
with 120 VAC from the control circuit when the
immersion thermostat senses a drop in stored
water temperature below the desired set point. A
magnetic coil in the contactor is energized to
complete the electrical circuit supplying power to
the immersion heating elements. When the
thermostat is satisfied, the contactor coil is de-
energized and power to the heating elements is
turned off.
CONTROL CIRCUIT TRANSFORMER
A transformer is used to reduce the line voltage to
120 VAC for internal control operation. The
transformer is fused on both the primary and
secondary side. The common side of the
secondary control circuit is grounded. The VA
rating of the control circuit transformer is based
on the load of the various components in the
water heater control circuit.
12
FIG. 14 Fuse Block with Power Circuit Fuses
FUSE AND FLUE BLOCKS
FIG. 15 Magnetic Contactor
CONTACTORS
CONTROL CIRCUIT TRANSFORMER
HAZARD OF ELECTRICAL SHOCK –
Before opening the electrical access panel
to adjust the thermostat or servicing the
water heater, make sure the electrical
supply to the water heater is turned “OFF”.
Failure to do this could result in death,
serious bodily injury or property damage.
WARNING:
FIG. 16 Control Circuit Transformer
