A.O. Smith DSE-5 Service Handbook page 29

Heating Element Voltage Test (cont)
A Single Phase Power - 3 Pole Contactor - Six Wire Element (see diagrams page 18):
1 Measure and record voltage to all three heating element loops between the first and third lower
terminals of the contactor - L1 & L2.
Note: All three element loops are wired to the first and third lower terminals on the contactor.
Repeat this procedure at each contactor(s) for other heating elements being tested.
B Single Phase Power - 4 Pole Contactor - Six Wire Element (see diagrams page 19):
1 Measure and record voltage to the #1 heating element loop between the first and second lower
terminals of the contactor - L1 & L2.
2 Measure and record voltage to the #2 heating element loop between the first and fourth lower
terminals of the contactor - L1 & L2.
3 Measure and record voltage to the #3 heating element loop between the third and fourth lower
terminals of the contactor - L1 & L2.
Note: All three voltage readings should be approximately the same. Repeat this procedure at each
contactor(s) for other heating elements being tested.
D Three Phase Power - 3 Pole Contactor - Six Wire Element (see diagrams page 20):
1 Measure and record voltage to the #1 heating element loop between the first and second lower
terminals of the contactor - L1 & L2.
2 Measure and record voltage to the #2 heating element loop between the first and third lower
terminals of the contactor - L1 & L3.
3 Measure and record voltage to the #3 heating element loop between the second and third lower
terminals of the contactor - L2 & L3.
Note: All three voltage readings should be approximately the same. Repeat this procedure at each
contactor(s) for other heating elements being tested.
D Three Phase Power - 4 Pole Contactor - Six Wire Element (see diagrams page 21):
1 Measure and record voltage to the #1 heating element loop between the first and second lower
terminals of the contactor - L1 & L2.
2 Measure and record voltage to the #2 heating element loop between the first and fourth lower
terminals of the contactor - L1 & L3.
3 Measure and record voltage to the #3 heating element loop between the third and fourth lower
terminals of the contactor - L2 & L3.
Note: All three voltage readings should be approximately the same. Repeat this procedure at each
contactor(s) for other heating elements being tested.
D Three Phase Power - 3 Pole Contactor - Three Wire Element (see diagrams page 22):
1 Measure and record voltage between the first & second lower terminals of the contactor - L1 & L2.
2 Measure and record voltage between the first & third lower terminals of the contactor - L1 & L3.
3 Measure and record voltage between the second & third lower terminals of the contactor - L2 & L3.
Note: All three voltage readings should be approximately the same. Repeat this procedure at each
contactor(s) for other heating elements being tested.
Service Notes: If the voltage is low or not present in any of the tests above - check power to the
water heater (pages 12 - 14). Check fuses (page 15). Ensure heating element power circuit wiring is
correct (see wiring diagram on water heater) ensure all wiring and connections are tight and making
good contact. Check contactors (see pages 34 - 38). If the measured voltage is a standard voltage
(277/208/240/480) but does not match the listed voltage on the water heater's rating label secure
power to the water heater. DO NOT place the water heater back in service. Call the toll free
Technical Support phone number listed on the back cover of this manual for further assistance.
Servicing should only be performed by a Qualified Service Agent
OPERATION & SERVICE
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