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Servicing should only be performed by a Qualified Service Agent
25
OPERATION & SERVICE
Heating Element Resistance & Ground Tests
This is a two part test. In the first part of this test the actual resistance (ohms) of each
heating element is measured. In the second part of this test each heating element is tested
for any continuity to ground to ensure the heating element is not shorted to ground. These
tests should be considered as third and fourth diagnostic procedures to be performed
whenever the results from the Heating Element Amperage Test showed a heating element
was not drawing the correct amps AND the results from the Heating Element Voltage Test
showed the element had the proper voltage applied.
Measuring Resistance
1 Determine what the actual voltage and KW rating is for the heating elements in the water heater being
serviced - see Heating Element Ratings and Heating Element Configurations on page 21. Replace any
elements that are not the proper rating for the water heater being serviced.
2 Secure power to the water heater at the main breaker or disconnect switch.
3 Verify with an AC volt meter that there is not any voltage present at the Power Distribution Block (see
Figures 1 and 2 on pages 8 and 9) and at the two wiring terminals on the ends of all heating elements.
4 Disconnect both power wires from the terminals on the top of all heating elements to be tested.
5 Using an ohm meter: set the ohm meter to a range just above the expected ohms (200 ohm range initially).
6 Touch the ohm meter probes between the two terminals on each heating element - see the image below.
Measure and record the resistance (ohms) at all heating elements being tested.
7 Compare the resistance value (ohms) measured to the values given in the Heating Element Resistance
table on page 22.
8 If the measured resistance (ohms) matches the values in the Heating Element Resistance table on page
22 the heating element resistance is correct.
9 If the resistance reading is infinite - no continuity at all between the two terminals - the heating element is
defective and must be replaced. During heating element replacement be sure to check fuses (page 17),
inspect contactors on Electronic Control Models (see page 31) and check all wiring and connections
between the heating elements, contactors, fuses and the power distribution block. Ensure all wiring and
connections are tight and making good contact - replace any wiring, fuses, contactors that are damaged or
show signs of excessive wear.
Measuring resistance (ohms) on an electric heating
element. Touch the two ohm meter probes to the two
terminals on the end of each heating element.