A main power terminal block is provided for field connection of the branch power supply to the electric water heater. All internal power circuits to the immersion heating elements are connected to the load side of the main terminal block. The line side of the terminal block has individual lug type connections properly sized for the recommended copper field wire size.
FUSES AND FUSE BLOCKS
FIG. 7 Fuse Block with Power Circuit Fuses
The internal power circuits of a water heater with a current draw in excess of 48 amps are 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.
When the immersion thermostat and contactor option is provided, the control circuit is also fused on the primary side of the control circuit transformer.
SURFACE THERMOSTATS
WITH HIGH LIMIT
FIG. 8 Surface Thermostat/High Limit
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.
The standard control system uses an individual surface mounted snap action thermostat with high limit for each heating element. The thermostat/high limit is mounted firmly against the tank, directly above each heating element. The surface thermostat has an adjustable temperature setting that can be varied from 110°F (43.3˚C) up to 180°F (82.2˚C) at the highest setting. Turn off all electrical power to the water heater before attempting to adjust the thermostats. The temperature setpoint adjustment is made on each thermostat by using a screwdriver. All surface thermostats may be set at the same temperature or they may be set a 2° to 4°F (1˚ to 2˚C) apart to step the elements on in stages. There is a blanket of fiberglass insulation installed over the heating elements and surface thermostats. This insulation must be removed before the thermostats can be adjusted. Each thermostat has a plastic cover installed to prevent accidental contact with power wires when adjusting the set point. This cover has an opening to allow temperature adjustment and resetting of the high limit. The cover does not have to be removed. The high water temperature limit control which is part of each thermostat assembly contains a manual reset on high water temperature.
8
