FUSE AND FLUE BLOCKS
FIG. 14 | Fuse Block with Power Circuit Fuses |
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.
CONTACTORS
FIG. 15 Magnetic Contactor
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
FIG. 16 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.
WARNING: 
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.
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